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The way a baby is positioned in the uterus just before birth can have a big effect on labor and delivery. This positioning is called fetal presentation.

Babies twist, stretch and tumble quite a bit during pregnancy. Before labor starts, however, they usually come to rest in a way that allows them to be delivered through the birth canal headfirst. This position is called cephalic presentation. But there are other ways a baby may settle just before labor begins.

Following are some of the possible ways a baby may be positioned at the end of pregnancy.

Head down, face down

When a baby is head down, face down, the medical term for it is the cephalic occiput anterior position. This the most common position for a baby to be born in. With the face down and turned slightly to the side, the smallest part of the baby's head leads the way through the birth canal. It is the easiest way for a baby to be born.

Head down, face up

When a baby is head down, face up, the medical term for it is the cephalic occiput posterior position. In this position, it might be harder for a baby's head to go under the pubic bone during delivery. That can make labor take longer.

Most babies who begin labor in this position eventually turn to be face down. If that doesn't happen, and the second stage of labor is taking a long time, a member of the health care team may reach through the vagina to help the baby turn. This is called manual rotation.

In some cases, a baby can be born in the head-down, face-up position. Use of forceps or a vacuum device to help with delivery is more common when a baby is in this position than in the head-down, face-down position. In some cases, a C-section delivery may be needed.

Frank breech

When a baby's feet or buttocks are in place to come out first during birth, it's called a breech presentation. This happens in about 3% to 4% of babies close to the time of birth. The baby shown below is in a frank breech presentation. That's when the knees aren't bent, and the feet are close to the baby's head. This is the most common type of breech presentation.

If you are more than 36 weeks into your pregnancy and your baby is in a frank breech presentation, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. It involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a breech position, talk with a member of your health care team about the choices you have for delivery. Most babies in a frank breech position are born by planned C-section.

Complete and incomplete breech

A complete breech presentation, as shown below, is when the baby has both knees bent and both legs pulled close to the body. In an incomplete breech, one or both of the legs are not pulled close to the body, and one or both of the feet or knees are below the baby's buttocks. If a baby is in either of these positions, you might feel kicking in the lower part of your belly.

If you are more than 36 weeks into your pregnancy and your baby is in a complete or incomplete breech presentation, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. It involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a breech position, talk with a member of your health care team about the choices you have for delivery. Many babies in a complete or incomplete breech position are born by planned C-section.

When a baby is sideways — lying horizontal across the uterus, rather than vertical — it's called a transverse lie. In this position, the baby's back might be:

• Down, with the back facing the birth canal.
• Sideways, with one shoulder pointing toward the birth canal.
• Up, with the hands and feet facing the birth canal.

Although many babies are sideways early in pregnancy, few stay this way when labor begins.

If your baby is in a transverse lie during week 37 of your pregnancy, your health care professional may try to move the baby into a head-down position. This is done using a procedure called external cephalic version. External cephalic version involves one or two members of your health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

If the procedure isn't successful, or if the baby moves back into a transverse lie, talk with a member of your health care team about the choices you have for delivery. Many babies who are in a transverse lie are born by C-section.

If you're pregnant with twins and only the twin that's lower in the uterus is head down, as shown below, your health care provider may first deliver that baby vaginally.

Then, in some cases, your health care team may suggest delivering the second twin in the breech position. Or they may try to move the second twin into a head-down position. This is done using a procedure called external cephalic version. External cephalic version involves one or two members of the health care team putting pressure on your belly with their hands to get the baby to roll into a head-down position.

Your health care team may suggest delivery by C-section for the second twin if:

• An attempt to deliver the baby in the breech position is not successful.
• You do not want to try to have the baby delivered vaginally in the breech position.
• An attempt to move the baby into a head-down position is not successful.
• You do not want to try to move the baby to a head-down position.

In some cases, your health care team may advise that you have both twins delivered by C-section. That might happen if the lower twin is not head down, the second twin has low or high birth weight as compared to the first twin, or if preterm labor starts.

• Landon MB, et al., eds. Normal labor and delivery. In: Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed May 19, 2023.
• Holcroft Argani C, et al. Occiput posterior position. https://www.updtodate.com/contents/search. Accessed May 19, 2023.
• Frequently asked questions: If your baby is breech. American College of Obstetricians and Gynecologists https://www.acog.org/womens-health/faqs/if-your-baby-is-breech. Accessed May 22, 2023.
• Hofmeyr GJ. Overview of breech presentation. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Strauss RA, et al. Transverse fetal lie. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Chasen ST, et al. Twin pregnancy: Labor and delivery. https://www.updtodate.com/contents/search. Accessed May 22, 2023.
• Cohen R, et al. Is vaginal delivery of a breech second twin safe? A comparison between delivery of vertex and non-vertex second twins. The Journal of Maternal-Fetal & Neonatal Medicine. 2021; doi:10.1080/14767058.2021.2005569.
• Marnach ML (expert opinion). Mayo Clinic. May 31, 2023.

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• Third Trimester
• Labor & Delivery

What Is Vertex Presentation?

Vertex presentation is just medical speak for “baby’s head-down in the birth canal and rearing to go!” About 97 percent of all deliveries are headfirst, or vertex—and rare is the OB who will try to deliver any other way.

Other, less common presentations include breech (when baby’s head is near your ribs) and transverse (which means the shoulder, arm or trunk is due to come out first because baby is lying on his side). Most babies will turn by about 34 weeks, but some have “unstable lies,” meaning they’re like a politician trying to make everyone happy—that is, they frequently flip positions.

About 95 percent of all babies will be head-down and ready to go by delivery day. If your little one isn’t vertex by 36 weeks, ask your doctor about your options. She may recommend doing a version procedure , in which the doctor tries to manually turn baby by pushing on your abdomen, but it does carry some risks and is only about 60 to 70 percent successful.

Expert: Melissa M. Goist, MD, assistant professor, obstetrics and gynecology, The Ohio State University Medical Center.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

Plus, more from The Bump:

Delivering a breech baby?

Shift breech baby before birth?

Will my baby be breech?

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Fetal Presentation, Position, and Lie (Including Breech Presentation)

, MD, Children's Hospital of Philadelphia

Variations in Fetal Position and Presentation

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Presentation refers to the part of the fetus’s body that leads the way out through the birth canal (called the presenting part). Usually, the head leads the way, but sometimes the buttocks (breech presentation), shoulder, or face leads the way.

Position refers to whether the fetus is facing backward (occiput anterior) or forward (occiput posterior). The occiput is a bone at the back of the baby's head. Therefore, facing backward is called occiput anterior (facing the mother’s back and facing down when the mother lies on her back). Facing forward is called occiput posterior (facing toward the mother's pubic bone and facing up when the mother lies on her back).

Lie refers to the angle of the fetus in relation to the mother and the uterus. Up-and-down (with the baby's spine parallel to mother's spine, called longitudinal) is normal, but sometimes the lie is sideways (transverse) or at an angle (oblique).

For these aspects of fetal positioning, the combination that is the most common, safest, and easiest for the mother to deliver is the following:

Head first (called vertex or cephalic presentation)

Facing backward (occiput anterior position)

Spine parallel to mother's spine (longitudinal lie)

Neck bent forward with chin tucked

Arms folded across the chest

If the fetus is in a different position, lie, or presentation, labor may be more difficult, and a normal vaginal delivery may not be possible.

Variations in fetal presentation, position, or lie may occur when

The fetus is too large for the mother's pelvis (fetopelvic disproportion).

The fetus has a birth defect Overview of Birth Defects Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious within the first year of life. The cause of many birth... read more .

There is more than one fetus (multiple gestation).

Position and Presentation of the Fetus

Some variations in position and presentation that make delivery difficult occur frequently.

Occiput posterior position

In occiput posterior position (sometimes called sunny-side up), the fetus is head first (vertex presentation) but is facing forward (toward the mother's pubic bone—that is, facing up when the mother lies on her back). This is a very common position that is not abnormal, but it makes delivery more difficult than when the fetus is in the occiput anterior position (facing toward the mother's spine—that is facing down when the mother lies on her back).

Breech presentation

In breech presentation, the baby's buttocks or sometimes the feet are positioned to deliver first (before the head).

When delivered vaginally, babies that present buttocks first are more at risk of injury or even death than those that present head first.

The reason for the risks to babies in breech presentation is that the baby's hips and buttocks are not as wide as the head. Therefore, when the hips and buttocks pass through the cervix first, the passageway may not be wide enough for the head to pass through. In addition, when the head follows the buttocks, the neck may be bent slightly backwards. The neck being bent backward increases the width required for delivery as compared to when the head is angled forward with the chin tucked, which is the position that is easiest for delivery. Thus, the baby’s body may be delivered and then the head may get caught and not be able to pass through the birth canal. When the baby’s head is caught, this puts pressure on the umbilical cord in the birth canal, so that very little oxygen can reach the baby. Brain damage due to lack of oxygen is more common among breech babies than among those presenting head first.

Breech presentation is more likely to occur in the following circumstances:

Labor starts too soon (preterm labor).

Sometimes the doctor can turn the fetus to be head first before labor begins by doing a procedure that involves pressing on the pregnant woman’s abdomen and trying to turn the baby around. Trying to turn the baby is called an external cephalic version and is usually done at 37 or 38 weeks of pregnancy. Sometimes women are given a medication (such as terbutaline ) during the procedure to prevent contractions.

Other presentations

In face presentation, the baby's neck arches back so that the face presents first rather than the top of the head.

In brow presentation, the neck is moderately arched so that the brow presents first.

Usually, fetuses do not stay in a face or brow presentation. These presentations often change to a vertex (top of the head) presentation before or during labor. If they do not, a cesarean delivery is usually recommended.

In transverse lie, the fetus lies horizontally across the birth canal and presents shoulder first. A cesarean delivery is done, unless the fetus is the second in a set of twins. In such a case, the fetus may be turned to be delivered through the vagina.

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Breech, posterior, transverse lie: What position is my baby in?

Fetal presentation, or how your baby is situated in your womb at birth, is determined by the body part that's positioned to come out first, and it can affect the way you deliver. At the time of delivery, 97 percent of babies are head-down (cephalic presentation). But there are several other possibilities, including feet or bottom first (breech) as well as sideways (transverse lie) and diagonal (oblique lie).

Fetal presentation and position

During the last trimester of your pregnancy, your provider will check your baby's presentation by feeling your belly to locate the head, bottom, and back. If it's unclear, your provider may do an ultrasound or an internal exam to feel what part of the baby is in your pelvis.

Fetal position refers to whether the baby is facing your spine (anterior position) or facing your belly (posterior position). Fetal position can change often: Your baby may be face up at the beginning of labor and face down at delivery.

Here are the many possibilities for fetal presentation and position in the womb.

Medical illustrations by Jonathan Dimes

Head down, facing down (anterior position)

A baby who is head down and facing your spine is in the anterior position. This is the most common fetal presentation and the easiest position for a vaginal delivery.

This position is also known as "occiput anterior" because the back of your baby's skull (occipital bone) is in the front (anterior) of your pelvis.

Head down, facing up (posterior position)

In the posterior position , your baby is head down and facing your belly. You may also hear it called "sunny-side up" because babies who stay in this position are born facing up. But many babies who are facing up during labor rotate to the easier face down (anterior) position before birth.

Posterior position is formally known as "occiput posterior" because the back of your baby's skull (occipital bone) is in the back (posterior) of your pelvis.

Frank breech

In the frank breech presentation, both the baby's legs are extended so that the feet are up near the face. This is the most common type of breech presentation. Breech babies are difficult to deliver vaginally, so most arrive by c-section .

Some providers will attempt to turn your baby manually to the head down position by applying pressure to your belly. This is called an external cephalic version , and it has a 58 percent success rate for turning breech babies. For more information, see our article on breech birth .

Complete breech

A complete breech is when your baby is bottom down with hips and knees bent in a tuck or cross-legged position. If your baby is in a complete breech, you may feel kicking in your lower abdomen.

Incomplete breech

In an incomplete breech, one of the baby's knees is bent so that the foot is tucked next to the bottom with the other leg extended, positioning that foot closer to the face.

Single footling breech

In the single footling breech presentation, one of the baby's feet is pointed toward your cervix.

Double footling breech

In the double footling breech presentation, both of the baby's feet are pointed toward your cervix.

Transverse lie

In a transverse lie, the baby is lying horizontally in your uterus and may be facing up toward your head or down toward your feet. Babies settle this way less than 1 percent of the time, but it happens more commonly if you're carrying multiples or deliver before your due date.

If your baby stays in a transverse lie until the end of your pregnancy, it can be dangerous for delivery. Your provider will likely schedule a c-section or attempt an external cephalic version , which is highly successful for turning babies in this position.

Oblique lie

In rare cases, your baby may lie diagonally in your uterus, with his rump facing the side of your body at an angle.

Like the transverse lie, this position is more common earlier in pregnancy, and it's likely your provider will intervene if your baby is still in the oblique lie at the end of your third trimester.

Was this article helpful?

What to know if your baby is breech

What's a sunny-side up baby?

What happens to your baby right after birth

How your twins’ fetal positions affect labor and delivery

BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies .

Ahmad A et al. 2014. Association of fetal position at onset of labor and mode of delivery: A prospective cohort study. Ultrasound in obstetrics & gynecology 43(2):176-182. https://www.ncbi.nlm.nih.gov/pubmed/23929533 Opens a new window [Accessed September 2021]

Gray CJ and Shanahan MM. 2019. Breech presentation. StatPearls.  https://www.ncbi.nlm.nih.gov/books/NBK448063/ Opens a new window [Accessed September 2021]

Hankins GD. 1990. Transverse lie. American Journal of Perinatology 7(1):66-70.  https://www.ncbi.nlm.nih.gov/pubmed/2131781 Opens a new window [Accessed September 2021]

Medline Plus. 2020. Your baby in the birth canal. U.S. National Library of Medicine. https://medlineplus.gov/ency/article/002060.htm Opens a new window [Accessed September 2021]

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Malpresentation, Malposition, Cephalopelvic Disproportion and Obstetric Procedures

26 Malpresentation, Malposition, Cephalopelvic Disproportion and Obstetric Procedures Kim Hinshaw 1,2 and Sabaratnam Arulkumaran 3 1 Sunderland Royal Hospital, Sunderland, UK 2 University of Sunderland, Sunderland, UK 3 St George’s University of London, London, UK Malpresentation, malposition and cephalopelvic disproportion Definitions The vertex is a diamond‐shaped area on the fetal skull bounded by the anterior and posterior fontanelles and laterally by the parietal eminences. Vertex presentation is found in 95% of labours at term and is associated with flexion of the fetal head. Breech, brow, face and shoulder presentations constitute the remaining 5% and are collectively known as malpresentations . Their aetiology is usually unknown, but associations include macrosomia, multiparity, polyhydramnios, multiple pregnancy, placenta praevia, preterm labour, and anomalies of the uterus or pelvis (congenital or acquired, e.g. lower segment fibroids) and more rarely the fetus. The denominator is a laterally sited bony eminence on the presenting part (‘occiput’ for vertex presentation, ‘mentum’ for face, ‘acromium’ for shoulder and ‘sacrum’ for breech). The position of the presenting part is defined by the relationship of the denominator to the maternal bony pelvis. The vertex enters the pelvis in the occipito‐transverse (OT) position and during descent rotates to an occipito‐anterior (OA) position in 90% of cases. This position is associated with a well‐flexed head, allowing the smallest anteroposterior (suboccipito‐bregmatic) and lateral (biparietal) diameters to pass through the pelvis (both 9.5 cm). Malposition occurs when the occiput remains in a tranverse or posterior position as labour progresses. Persistent malposition results in deflexion with a larger anteroposterior diameter presenting (occipito‐frontal 11.5 cm). It is associated with increasing degrees of anterior or posterior asynclitism , with one of the parietal bones preceding the sagittal suture (in posterior asynclitism, the posterior parietal bone leads; Fig. 26.1 ). Significant degrees of asynclitism can result in labour dystocia and a higher risk of operative delivery [1] . Fig. 26.1 Posterior asynclitism of the vertex: posterior parietal bone presenting below the sagittal suture. In most cases, flexion occurs as the vertex descends onto the pelvic floor, leading to correction of the malposition and a high chance of spontaneous delivery. The level of the presenting part should be critically assessed as labour progresses. On abdominal examination, the head should descend until it is no more than 1/5 palpable in the late first stage. On vaginal examination the presenting part is assessed relative to the level of the ischial spines. Care must be taken to assess the level using the lowest bony part . Malposition is associated with increased moulding of the fetal skull and a large caput succedaneum, which may give false reassurance about the true degree of descent. In modern obstetric practice, operative vaginal delivery is not attempted if the leading edge of the skull is above the ischial spines (i.e. above ‘0’ station; Fig. 26.2 ). Fig. 26.2 Level of the presenting part relative to the ischial spines. Malpresentations Breech presentation The incidence of breech presentation varies according to gestation: 20% at 30 weeks falling to 4% by term. The aetiology of most breech presentations at term is unclear but known factors to consider include placenta praevia, polyhydramnios, bicornuate uterus, fibroids and, rarely, spina bifida or hydrocephaly. Types of breech presentation Between 50 and 70% of breech presentations manifest with hips flexed and knees extended (extended breech) Complete (or flexed) breech is more common in multiparous women and constitutes 5–10% at term (hips and knees flexed; Fig. 26.3 ). Incomplete or footling breech (10–30%) presents with one or both hips extended, or one or both feet presenting and is most strongly assoiated with cord prolapse (5–10%). Knee presentation is rare. Fig. 26.3 The common types of breech presentation. Clinical diagnosis may miss up to 20% of breech presentations, relying on identifying the head as a distinct hard spherical hard mass to one or other side under the hypochondrium which distinctly ‘ballots’. In such cases the breech is said to feel broader and an old adage reminds us: ‘Beware the deeply engaged head – it is probably a breech!’ Auscultation may locate the fetal heart above the maternal umbilicus and ultrasound confirmation should be considered. Antenatal management If breech presentation is suspected at 36 weeks, ultrasound assessment is recommended as it allows a comprehensive assessment of the type of breech, placental site, estimated fetal weight, confirmation of normality and exclusion of nuchal cord or hyperextension of the fetal neck. External cephalic version (ECV) is encouraged after 36 or more weeks as the chance of spontaneous version to cephalic presentation after 37 weeks is only 8%. Absolute contraindications are relatively few but include placenta praevia, bleeding within the last 7 days, abnormal cardiotocography (CTG), major uterine anomaly, ruptured membranes and multiple pregnancy [2] . Couples should receive counselling about the procedure and its success rates and complications, and the subsequent management of persistent breech presentation. Tocolysis increases the likelihood of success, with average rates of 50% (range 30–80%). Women should be made aware that even with a cephalic presentation following ECV, labour is still associated with a higher rate of obstetric intervention than when ECV has not been required. ECV should be performed in a setting where urgent caesarean section (CS) is available in case of fetal compromise during or soon after ECV. CTG for 30–40 min prior to and after ECV should provide confirmation of fetal health. The chance of success is greater with multiparity, flexed breech presentation and an adequate liquor volume. The use of moxibustion at 33–35 weeks, in combination with acupuncture, may reduce the numbers of births by CS. Training specialist midwives is potentially cost‐efficient with success rates comparable to consultant‐led services (51–66%) [3] . The first step in ECV involves disengaging the breech by moving the fetus up and away from the pelvis, shifting it to a sideways position, followed by a forward somersault to move the head to the lower pole; if this fails a backward somersault can be tried. The need for emergency delivery by CS because of suspected fetal compromise is estimated to be 0.5%. Mothers who are rhesus‐negative should have a Kleihauer–Betke test after the procedure and receive anti‐D. If ECV is unsuccessful, women who are keen to avoid CS may be offered a repeat attempt under neuraxial blockade. This increases the chances of success (58.4% vs. 43.1%; relative risk, RR 1.44, 95% CI 1.27–1.64) and reduces the incidence of CS (46.0% vs. 55.3%; RR 0.83, 95% CI 0.71–0.97) [4] . Otherwise appropriate counselling about the options of elective CS or assisted vaginal breech delivery should be offered. Deciding mode of delivery Despite increasing evidence supporting elective CS for breech delivery at term, controversy and debate continue among professional groups. Breech presentation at term diagnosed antenatally . The Term Breech Trial is the largest published randomized controlled trial where the primary outcome (serious perinatal morbidity and mortality) favoured planned CS over planned vaginal birth: 17/1039 (1.6%) versus 50/1039 (5.0%; RR 0.33, 95% CI 0.19–0.56; P <0.0001) [5] . The trial concluded that ‘planned CS is better than planned VB for the term fetus in the breech presentation; serious maternal complications are similar between the groups’. This has significantly changed practice in many countries despite continuing debate and criticism about the trial design and intepretation of outcomes. However, the latest systematic review has confirmed a significant increased perinatal risk associated with planned vaginal birth [6] . Breech at term diagnosed in labour and preterm breech delivery . Observational trials of term breech ‘undiagnosed’ until presentation in labour confirm that this group has a high vaginal delivery rate with relatively low perinatal morbidity. In a similar vein, the evidence to guide best practice for delivery of the preterm breech remains equivocal, decisions often being based on individual interpretation of the data and local custom and practice. Conducting a vaginal breech delivery For women who wish to deliver vaginally, antenatal selection aims to ensure optimal outcome for mother and baby but remains relatively subjective. Women with frank and complete breech presentations (fetal weight <4000 g) encounter minimal problems, while those with footling breech are advised elective CS because of the increased risk of cord prolapse. CT or X‐ray pelvimetry do not appear to improve outcome. Spontaneous onset of labour is preferred and labour management is similar to vertex presentation. Successful outcome depends on a normal rate of cervical dilatation, descent of the breech and a normal fetal heart rate (FHR) pattern. Where progress of labour is poor and uterine contractions are inadequate, oxytocin augmentation can be used juidiciously with early resort to emergency CS if progress remains slow (<0.5 cm/hour), particularly in the late first stage. Epidural anaesthesia prevents bearing down before the cervix is fully dilated and is particularly important for labour with a preterm breech, when there is a real risk of head entrapment in the incompletely dilated cervix if pushing commences too early. For all breech labours, the mother should be encouraged to avoid bearing down for as long as possible. It is best to wait until the anterior buttock and anus of the baby are in view over the mother’s perineum, with no retraction between contractions. Classically, the mother’s legs are supported in the lithotomy position (the alternative upright breech technique is described later). Primigravidae will usually require an episiotomy with appropriate analgesia, although multigravidae can be assessed as the perineum stretches up. The buttocks deliver in the sacro‐tranverse position. The mother should be encouraged to push with contractions, aiming for an unassisted delivery up to and beyond the level of the umbilicus. There is no need to pull down a loop of cord. The accoucheur should sit with hands ready, but resting on their own legs. Assistance is only required if the legs do not deliver. Gentle abduction of the fetal thigh whilst hyperflexing the hip, followed by flexing the lower leg at the knee will release the foot and leg ( Fig. 26.4 ). Fig. 26.4 Delivery of extended legs by gentle abduction of the thigh with hyperflexion at the hip, followed by flexion at the knee: (a) right leg; (b) left leg. When the scapulae are visible with the arms flexed in front of the chest, sweep each arm around the side of the fetal chest to deliver using a finger placed along the length of the humerus. If the scapulae are not easily seen or if the arms are not easily reached, they may be extended above the shoulders. This can be resolved using the Løvset manoeuvre. Hold the baby by wrapping both hands around the bony pelvis, taking care not to apply pressure to the soft fetal abdomen. Rotate the baby 180° to bring the posterior shoulder to the front, i.e. to lie anteriorly ( Fig. 26.5 a). Complete delivery of the anterior arm by gently flexing the baby laterally downwards towards the floor; the arm will deliver easily from under the pubic ramus ( Fig. 26.5 b). Repeat the 180° rotation in the opposite direction, bringing the posterior shoulder to the front, then flex the baby laterally downwards to deliver the second arm. Fig. 26.5 Løvset’s manoeuvre for extended arms: (a) rotation to bring the posterior (left) arm to the front followed by (b) delivery of the left arm (now anterior) from under the pubic ramus. Nuchal displacement (an arm trapped behind the fetal neck) is rare. If the left arm is trapped, the baby will need to be rotated in a clockwise direction to ‘unwrap’ the arm so that it can be reached. If the right arm is involved, anticlockwise rotation is needed. Allow the head to descend into the pelvis, assisted by the weight of the fetus until the nape of the neck is visible under the symphysis pubis. Ensure slow controlled delivery of the head using one of four methods. Mauriceau–Smellie–Veit manoeuvre: two fingers are placed on the maxilla, lying the baby along the forearm. Hook index and fourth fingers of the other hand over the shoulders with the middle finger on the occiput to aid flexion. Apply traction to the shoulders with an assistant applying suprapubic pressure if needed ( Fig. 26.6 ). Burns–Marshall method: grasp the feet, apply gentle traction and swing the baby gently up and over the maternal abdomen until the mouth and nose appear. Forceps are applied to the head from below, with an assistant supporting the baby’s body in the horizontal plane avoiding hyperextension. Kielland’s forceps can be useful as they lack a pelvic curve. Apply traction, bringing the forceps upwards as the mouth and nose appear. The upright breech technique is increasingly popular in midwifery deliveries. Mobility is encouraged with delivery on all fours, sitting (on a birth stool), kneeling, standing or lying in a lateral position. Delivery is spontaneous with no manual assistance in 70% of cases and a reduced incidence of perineal trauma (14.9%). Fig. 26.6 Delivery of the head using the Mauriceau–Smellie–Veit manoeuvre assisted by suprapubic pressure. Entrapment of the aftercoming head This rare complication occurs in two situations. If the fetal back is allowed to rotate posteriorly, the chin may be trapped behind the symphysis pubis. Correction requires difficult internal manipulation to free the chin by pushing it laterally. McRoberts’ manoeuvre and suprapubic pressure may help. Symphysiotomy is a last resort that can increase the available pelvic diameters. In preterm delivery, the body can slip through an incompletely dilated cervix, with resulting head entrapment. If the cervix cannot be ‘stretched up’ digitally, surgical incisions are made in the cervical ring at 2, 6 and 10 o’clock (Dührssen incisions). Head entrapment in the contractile upper segment can occur at CS. Acute tocolysis and/or extension of the uterine incision may be required to release the head. Women should be intimately involved in decisions about mode of breech delivery and the available evidence presented appropriately. A senior midwife or a doctor experienced in assisted breech delivery must be present. As vaginal breech deliveries decline, developing expertise in breech delivery now relies on simulation training and experience of breech delivery at CS. Summary box 26.1 ECV has a high success rate (51–66%) and should be encouraged. Ensure the fetal back does not rotate posteriorly during breech delivery. The most experienced accoucheur available should directly supervise vaginal breech delivery. Brow presentation Brow presentation occurs in 1 in 1500–3000 deliveries. The head is partially deflexed (extended), with the largest diameter of the head presenting (mento‐vertical, 13.5 cm). The forehead is the lowest presenting part but diagnosis relies on identifying the prominent orbital ridges lying laterally. The eyeballs and nasal bridge may just be palpated lateral to the orbital ridges. Position is defined using the frontal bone as the denominator (i.e. ‘fronto‐‘). Persistent brow presentation results in true disproportion, but when diagnosed in early labour careful assessment of progress is appropriate. Flexion to vertex or further extension to face presentation occurs in 50% and vaginal delivery is possible. Cautious augmentation with oxytocin should only be considered in nulliparous patients for delay in the early active phase of labour. If brow presentation persists, emergency CS is recommended. Vaginal delivery of a brow presentation is possible in extreme prematurity. Preterm labour is best managed in the same way as term labour, with delivery by CS if progress slows or arrests. Cord prolapse is more common and, though rare, uterine rupture can occur in neglected labour or with injudicious use of oxytocin. For this reason labour should not be augmented in multigravid patients with a confirmed brow presentation if progress is inadequate. Face presentation Face presentation occurs in 1 in 500–800 labours. The general causes of malpresentation apply for face presentation, but fetal anomalies (neck or thyroid masses, hydrocephalus and anencephaly) should be excluded. The fetal head is hyperextended and the occiput may be felt higher and more prominently on the same side as the fetal spine. However, face presentation is rarely diagnosed antenatally. On vaginal examination in labour, diagnosis relies on feeling the mouth, malar bones, nose and orbital ridges. Position is defined using the chin or mentum as the denominator. The mouth and malar bones form a triangle which can help differentiate face presentation from breech, where the anus lies in a straight line between the prominent ischial tuberosities. Face presentation is often first diagnosed in late labour. The submento‐bregmatic diameter (9.5 cm) is compatible with normal delivery but only with the fetus in a mento‐anterior position (60%) ( Fig. 26.7 ). The same diameter presents with a persistent mento‐posterior position (25%) but this cannot deliver vaginally as the fetal neck is maximally extended. Fetal scalp clips, blood sampling and vacuum extraction are absolutely contraindicated. Forceps delivery from low cavity can be undertaken for mento‐anterior or mento‐lateral positions by an experienced accoucheur but CS may still be required when descent is poor. Fig. 26.7 The anteroposterior submento‐bregmatic diameter of face presentation. Shoulder presentation The incidence of shoulder presentation at term is 1 in 200 and is found with a transverse or oblique lie. Multiparity (uterine laxity) and prematurity are common associations and placenta praevia must be excluded. The lie will usually correct spontaneously before labour as uterine tone increases, although prolapse of the cord or arm is a significant risk if membranes rupture early. For this reason, hospital admission from 38 weeks is recommended for persistent transverse lie. External version can be offered (and may also be considered for transverse lie presenting in very early labour). On vaginal examination, the denominator is the acromium but defining position can be difficult. If membrane rupture occurs at term with the uterus actively contracting, delivery by CS should be undertaken promptly to avoid an impacted transverse lie. If the uterus is found to be moulded around the fetus, a classical CS is recommended to avoid both fetal and maternal trauma. In cases of intrauterine death with a transverse lie, spontaneous vaginal delivery is possible for early preterm fetuses by extreme flexion of the body (spontaneous evolution). However, CS will usually be required beyond mid‐trimester, although a lower segment approach may be used. Malposition and cephalopelvic disproportion In higher‐income countries, cephalopelvic disproportion is usually ‘relative’ and due to persistent malposition or relative fetal size (macrosomia). Classically we consider these problems with regard to the passage, the passenger or the powers, either alone or in combination. The passage Absolute disproportion due to a contracted pelvis is now rare in higher‐income countries unless caused by severe pelvic trauma and this should be known before the onset of labour. Caldwell and Moloy described four types of pelvis: gynaecoid (ovoid inlet, widest transversely, 50%), anthropoid (ovoid inlet, widest anteroposterior, 25%), android (heart‐shaped inlet, funnel‐shaped, 20%) and platypelloid (flattened gynaecoid, 3%). These can influence labour outcome but as pelvimetry is rarely used and clinical assessment of pelvic shape is inaccurate, this rarely influences clinical mangement in labour. The anthropoid pelvis is associated with a higher risk of persistent occipito‐posterior (OP) position and relative disproportion. The passenger and OP malposition Fetal anomalies (e.g. hydrocephalus, ascites) where disproportion may be a problem in labour are usually assessed antenatally and delivery by elective CS considered. Fetal macrosomia is increasing, related to the rising body mass index (BMI) in many pregnant populations. The evidence for inducing non‐diabetic women with an estimated fetal weight above the 90th centile (or >4000 g) in order to reduce cephalopelvic disproportion remains equivocal. Malposition is an increasingly common cause of disproportion and may be related to a sedentary lifestyle. OP position is associated with deflexion and/or asynclitism with a larger diameter presenting. Optimal uterine activity will correct the malposition in 75% of cases. Flexion occurs as the occiput reaches the pelvic floor with long rotation through 135° to an OA position and a high chance of normal delivery. Moulding of the fetal skull and pelvic elasticity (related to changes at the symphysis pubis) are dynamic changes that facilitate progress in labour and delivery. Short rotation through 45° to direct OP can result in spontaneous ‘face to pubes’ delivery, although episiotomy may be required to allow the occiput to deliver. Persistent OP position occurs in up to 25% of cases and is associated with further deflexion. The risk of assisted delivery is high because of relative disproportion as the presenting skull diameters increase. Delivery in the OP position from mid‐cavity (0 to +2 station) requires critical assessment to decide whether delivery should be attempted vaginally or abdominally and is discussed in later sections. The powers Disproportion is intimately related to dystocia and failure to progress in labour. National Institute for Health and Care Excellence (NICE) guidelines recommend that first stage delay is suspected with cervical dilatation of less than 2 cm in 4 hours when forewater amniotomy should be offered. Delay is confirmed if progress is less than 1 cm 2 hours later and oxytocin augmentation should be offered [6] . This shortens labour but does not affect operative delivery rates. High‐dose oxytocin may reduce CS rates but larger trials are required before these regimens are used routinely. The decision to use oxytocin in labour arrest in multigravid patients must only be made by the most senior obstetrician and should always be approached with extreme caution as uterine rupture is a possible consequence. In the second stage, particularly with epidural analgesia, passive descent for at least 1 hour is recommended, and possibly longer if the woman wishes, before encouraging active pushing. With regional analgesia and a normal FHR pattern, birth should occur within 4 hours of full dilatation regardless of parity [7] . Oxytocin may be commenced in nulliparous patients in the passive phase if contractions are felt to be inadequate and particularly with the persistent OP position. Failure of second‐stage descent combined with excessive caput or moulding suggests disproportion and requires critical assessment to decide the appropriate mode of delivery. Summary box 26.2 OP position with deflexion of the head and asynclitism results in relative disproportion compounded by inadequate uterine activity. With epidural analgesia in place, passive descent should be encouraged for at least 1 hour. Augmentation with oxytocin should be used with extreme caution in multigravid patients with labour arrest. Instrumental vaginal deliveries Background The incidence of instrumental vaginal delivery (IVD) varies widely and in Europe ranges from 0.5% (Romania) to 16.4% (Ireland), although there is no direct relationship with CS rates [ 8 , 9 ]. Epidural analgesia is associated with higher IVD rates. Allowing a longer passive second stage for descent results in less rotational deliveries and possibly a reduction in second‐stage CS [ 10 , 11 ]. Common indications for IVD include delay in the second stage of labour due to inadequate uterine activity, malposition with relative disproportion, maternal exhaustion and fetal compromise. Women with severe cardiac, respiratory or hypertensive disease or intracranial pathology may require IVD to shorten the second stage (when forceps may be preferred). Assessment and preparation for IVD The condition of the mother and fetus and the progress of labour should be assessed prior to performing IVD. Personal introductions to the woman and her partner are essential, explaining the reason for IVD and ensuring a chaperone and enough support are available. The findings, plan of action and the procedure itself should be explained and the discussions carefully recorded. Verbal or written consent is obtained. The mother and her partner may be physically and emotionally exhausted and great care should be exercised in terms of behaviour, communication and medical action. On abdominal examination, the fetal head should be no more than 1/5 palpable (preferably 0/5). A scaphoid shape to the lower abdomen may indicate an OP position. The FHR pattern should be assessed, noting any clinical signs of fetal compromise (e.g. fresh meconium). With acute fetal compromise (e.g. profound bradycardia, cord prolapse) delivery must be expedited urgently and this may only allow a brief explanation to be given to the patient and her partner at the time. If contractions are felt to be infrequent or short‐lasting, an oxytocin infusion should be considered in the absence of signs of fetal compromise. Both vacuum and forceps deliveries are associated with an almost threefold increased risk of shoulder dystocia compared with spontaneous delivery and this should be anticipated. However, it remains unclear whether this increased incidence is a cause or effect phenomenon [12] . On vaginal examination the cervix should be fully dilated with membranes absent. The colour and amount of amniotic fluid is recorded. Excessive caput or moulding may suggest the possibility of disproportion. Inability to reduce overlapping skull bones with gentle pressure is designated ‘moulding +++’; overlapping that reduces by gentle digital pressure is ‘moulding ++’, and meeting of the bones without overlap is ‘moulding +’. Identification of position, station, degree of deflexion and asynclitism will help decide whether IVD is appropriate, where it should be undertaken and who should undertake the procedure. Successful IVD is associated with station below the spines and progressive descent with pushing. If the head is 1/5 palpable abdominally, the leading bony part of the head is at the level of the ischial spines (mid‐cavity). When the head is more than 1/5 palpable and/or when station is above the spines, delivery by CS is recommended. Position is determined by identification of suture lines and fontanelles. The small posterior fontanelle (PF) lies at the Y‐shaped junction of the sagittal and lambdoidal sutures but may be difficult to feel when there is marked caput. The anterior fontanelle (AF) is a larger diamond‐shaped depression at the junction of the two parietal and two frontal bones. It can be differentiated from the PF by identifying the four sutures leading into the fontanelle. In deflexion (particularly OP positions) the AF lies centrally and is easily felt. Position can be confirmed by reaching for the pinna of the fetal ear, which can be flicked forwards indicating that the occiput lies in the opposite direction. Reaching the ear suggests descent below the mid‐pelvic strait. The degree of asynclitism should be assessed (see Fig. 26.1 ), with increasing degrees suggesting disproportion and a potentially more difficult IVD. Assessment of level and position can be difficult with OP position and in obesity. If there is any doubt after careful clinical examination, ultrasound assessment is recommended. The fetal orbits are sought and the position of the spine is noted. This is simple to do and can reduce the incorrect diagnosis of fetal position without delaying delivery, although on its own may not reduce morbidity associated with IVD [13] . IVD is normally performed with the mother in the dorsal semi‐upright position with legs flexed and abducted, supported by lithotomy poles or similar. The procedure is performed with good light and ideally aseptic conditions. The vulva and perineum should be cleansed and the bladder catheterized if the woman is unable to void. Adequate analgesia is essential and requires careful individualized assessment. Epidural anaesthesia is advisable for mid‐cavity IVD (i.e. station 0 to +2 cm below the ischial spines; see Fig. 26.2 ). In the absence of a pre‐existing epidural, spinal anaesthesia may be considered. IVD at station +2 cm or below is termed ‘low‐cavity’ and regional or pudendal block with local perineal infiltration (20 mL 1% plain lidocaine) can be used. Outlet IVD is performed when the head is on or near the perineum with the scalp visible without separating the labia. Descent to this level is associated with an OA position requiring minimal or no rotation and perineal infiltration with pudendal anaesthesia is effective. When the vertex is below the spines, IVD is carried out with different types of forceps or vacuum equipment, depending on the position and station of the vertex and the familiarity and experience of the doctor. Overall, comparing outcomes is easier if designation is by station and position at the time of instrumentation (e.g. left OP at +3) rather than simply mid, low or outlet IVD [ 11 , 14 ]. Choice of instruments: forceps or ventouse The choice of instrument depends on the operator’s experience, familiarity with the instrument, station and position of the vertex. Therefore, knowledge of the station and the position of the vertex is essential. The fetus in an OA position in the mid/low cavity can be delivered using non‐rotational, long or short‐handled forceps or a vacuum device: silicone, plastic or anterior metal cups (with suction tubing arising from the dorsum of the cup) are all suitable. For the fetus lying OT at mid‐ or low‐cavity, or lying OP position mid‐cavity, Kielland’s forceps or vacuum devices can be used to correct the malposition. Manual rotation is another technique to consider. Low‐cavity direct OP positions can be delivered ‘face to pubis’ but this may cause signifcant perineal trauma as the occiput delivers. For this reason, an OP vacuum cup (with the suction tubing arising from the edge of the cup) may be preferred. The cup will promote flexion and late rotation to OA often occurs on the perineum just prior to delivery. The Kiwi OmniCup® is an all‐purpose disposable vacuum delivery system with a plastic cup and in‐built PalmPump™ suitable for use in all positions of the vertex. Later models also display force traction to help the accoucheur avoid cup slippage ( http://clinicalinnovations.com/portfolio‐items/kiwi‐complete‐vacuum‐delivery‐system/ ) Forceps delivery Forceps come in pairs and most have fenestrated blades with a cephalic and pelvic curve between the heel and toe (distal end) of each blade. The heel continues as a shank which ends in the handle. The handles of the two blades sit together and meet at the lock. The cephalic curve fits along either side of the fetal head with the blades lying on the maxilla or malar eminences in the line of the mento‐vertical diameter ( Fig. 26.8 a). When correctly attached, uniform pressure is applied to the head, with the main traction force applied over the malar eminences. The shanks are over the flexion point, allowing effective traction in the correct direction. Non‐rotational forceps (the longer‐handled Neville Barnes or Simpson, and the shorter‐handled Wrigley’s) have a distinct pelvic curve that allows the blades to lie in the line of the pelvic axis whilst the handles remain horizontal. Kielland’s forceps have a minimal pelvic curve to allow rotation within the pelvis to correct malposition. Fig. 26.8 (a) Malar forceps application showing mento‐vertical diameter; (b) forceps traction (Pajot’s manoeuvre). Prior to applying forceps, the blades should be assembled to check whether they fit together as a pair. All forceps have matching numbers imprinted on the handles or shanks and these should also be checked. Non‐rotational forceps can be applied when the vertex is no more than 45° either side of the direct OA position (i.e. right OA to left OA). Application and delivery in a direct OP position is also possible but not routinely recommended because of increased perineal trauma. The left blade is inserted first using a light ‘pencil grip’, negotiating the pelvic and cephalic curves with a curved movement of the blade between the fetal head and the operator’s right hand, which is kept along the left vaginal wall for protection. Hands are swapped to insert the right blade using the same technique. Correct application results in the handles lying horizontally, right on top of left, and locking should be easy. Before applying traction, correct application must be confirmed: (i) the sagittal suture is lying midline, equidistant from and parallel to the blades; (ii) the occiput is no more than 2–3 cm above the level of the shanks (i.e. head well‐flexed); and (iii) no more than a fingertip passes into the fenestration at the heel of the blade. From mid‐ and low‐cavity, Pajot’s maneouvre should be used, balancing outward traction with one hand with downward pressure on the shanks with the other ( Fig. 26.8 b, white arrow). The handles are kept horizontal to avoid trauma to the anterior vaginal wall from the toes of the blades. Traction is synchronized with contractions and maternal effort, and the resultant movement is outwards down the line of the pelvic axis until the head is crowning. An episiotomy is usually needed as the perineum stretches up. The direction of traction is now upwards once the biparietal eminences emerge under the pubic arch and the head is born by extension. The mother will usually ask to have her baby handed to her immediately (unless active resuscitation is required). After completing the third stage, any perineal trauma is repaired and a full surgical count completed. The procedure, including plans for analgesia and bladder care, should be fully documented. Rotational forceps Kielland’s forceps have a minimal pelvic curve allowing rotation of the head at mid‐cavity. They are powerful forceps requiring a skilled accoucheur who is willing to abandon the procedure if progress is not as expected. The number of units able to teach use of Kielland’s forceps to the point of independent practice is declining in the UK. The forceps should match and are applied so that the knobs on the handles face the fetal occiput. Kielland’s are used to correct both OT and OP positions using two methods of application. Direct application involves sliding each blade along the side of the head if space permits, and is more easily achieved with OP positions. Wandering application is useful in OT positions. The first blade is applied in front of the fetal face, from where it is gently ‘wandered’ around to lie in the usual position alongside the malar bone. The posterior blade is applied directly using the space in the pelvic sacral curve. If application is difficult or the blades do not easily lock, the procedure should be abandoned. Correct application should be confirmed. Once locked, it is essential to hold the handles at a relatively steep angle downwards in the line of the mid‐pelvic axis in order to achieve easy rotation. Asynclitism is corrected using the sliding lock, moving the shanks over each other until the knobs are aligned. Rotation should take place between contractions, using only gentle force. Rotation may require the fetal head to be gently disimpacted, either upwards or downwards but no more than 1‐cm displacement is needed. Correct application should be checked again after rotation. Traction should result in progressive descent and an episiotomy is usually required. At the point of delivery, the handles of Kielland’s are only just above the horizontal because of the lack of pelvic curve. If there is no descent with traction during three contractions with maternal effort, the procedure should be abandoned. Whether Kielland’s delivery takes place in the delivery room or in obstetric theatre requires careful assessment of fetal and maternal condition, analgesia and labour progress. If there is any doubt, a formal trial of forceps should be arranged. Vacuum delivery Ventouse or vacuum delivery is increasingly favoured over forceps delivery for similar indications in the second stage of labour. The prerequisites to be satisfied before vacuum delivery are the same as for all forms of IVD. Vacuum delivery is contraindicated below 34 +0 weeks and should be used with caution between 34 +0 to 36 +0 weeks [11] . Overall it is contraindicated for fetuses with possible haemorrhagic tendencies (risk of subgaleal haemorrhage) and before full dilatation [11] . Experienced practitioners may consider vacuum after 8 cm in a multigravid patient in some circumstances. There are many types of vacuum cup in regular use, made of different materials and of differing shapes. Whichever cup is used, the aim is to ensure that the centre of the cup is directly over the flexion point. The flexion point is 3 cm in front of the occiput in the midline and is the point where the mento‐vertical diameter exits the fetal skull [15] . Traction on this point promotes flexion, presenting the smallest diameters for descent through the pelvis: this is the optimum flexing median application ( Fig. 26.9 a). Other applications increase the risk of cup detachment, failed vacuum delivery and scalp trauma. In decreasing order of effectiveness, these are the flexing paramedian application ( Fig. 26.9 b), the deflexing median application ( Fig. 26.9 c) and the deflexing paramedian application ( Fig. 26.9 d). Fig. 26.9 Placement of the vacuum cup, from most favourable (a) to unfavourable (d). (a) Flexing median; (b) flexing paramedian; (c) deflexing median; (d) deflexing paramedian. It is vitally important to select the correct cup and this will vary depending on both the position and attitude of the fetus. The soft Silc, Silastic or anterior metal cups (where the tubing is attached on the dorsum of the cup) are not suitable for OT or OP positions, as their shape and configuration do not allow application over the flexion point. They are suitable for OA positions where the flexion point is accessible in the midline. Metal cups come in different sizes, usually 4, 5 or 6 cm in diameter. In a systematic review they were more likely to result in successful vaginal birth than soft cups (RR 1.63, 95% CI 1.17–2.28), but with more cases of scalp injury (RR 0.67, 95% CI 0.53–0.86) and cephalhaematoma (RR 0.61, 95% CI 0.39–0.95) [16] . A specially designed cup should be used for OT and OP positions: metal OP cups have tubing emerging from the lateral aspect of the cup and the Kiwi OmniCup has a groove in the dorsum of the cup to accommodate the flexible stem. These cups can be manoeuvred more laterally or posteriorly to reach the flexion point. Hand‐held vacuum is associated with more failures than metal ventouse [16] , although a larger study suggested that the OmniCup has an overall failure rate of 12.9% [11] . Aldo Vacca (1941–2014) was the doyen of vacuum delivery and (with reference to the flexion point and cup application) his favourite quote was ‘It’s always more posterior than you think’. After ensuring flexion point application, the cup must be held firmly on the fetal scalp, and a finger should be run around the rim to ensure that no maternal tissue is entrapped. A vacuum of 0.2 bar (150 mmHg or 0.2 kg/cm 2 negative pressure) is created using a hand‐held or mechanical pump, before rechecking the position over the flexion point and confirming maternal tissue is not trapped. The vacuum is increased to 0.7–0.8 bar (500–600 mmHg or 0.8 kg/cm 2 ) in one step, waiting 2 min where possible to develop the ‘chignon’ within the cup. Axial traction in the line of the pelvic axis should be timed with uterine contractions and maternal pushing. A thumb should be placed on the cup, with the index finger on the scalp at the edge of the cup allowing the operator to feel any potential detachment before it is heard (by which point it is often too late to prevent detachment). Descent promotes auto‐rotation of the head to the OA position and episiotomy is often not required. Parents should be reassured that the ‘chignon’ will settle over 2–3 days. Manual rotation Manual rotation for persistent OP position is an alternative to IVD. The procedure requires insertion of one hand into the posterior vagina to encourage flexion and rotation. Careful patient selection is essential and the operator must ensure that effective analgesia is in place. The right hand is inserted for a left OP position (insert left hand for right OP). Four fingers are placed behind the fetal occiput to act as the ‘gutter’ on which the head will rotate, with the thumb placed alongside the anterior fontanelle. When the mother pushes with a contraction, the thumb applies pressure to flex the head and rotation to an OA position should occur with minimal effort. In a series ( N  = 61) where OP position was managed in two groups, the spontaneous delivery rate increased from 27% to 77% in the group offered digital rotation ( P <0.0001) [17] . Complications of IVD In a Cochrane review of 32 studies ( N  = 6597), forceps were less likely to fail to achieve a vaginal birth compared with ventouse (RR 0.65, 95% CI 0.45–0.94) [16] . Vaginal and perineal lacerations, including third‐ and fourth‐degree tears, are more common with forceps than with vacuum. Infra‐levator haematomas may occur occasionally and these should be drained if large or symptomatic. The risk of flatus incontinence or altered continence is also higher. Follow‐up of women who have had low or outlet IVD confirms normal physical and neourological outcomes for the vast majority of the newborn. In terms of neonatal outcome, cephalhaematoma is more common with vacuum but risk of facial injury is less. Facial and scalp abrasions are usually minor and heal in a few days. Unilateral facial nerve palsy is rare and resolves within days or weeks and is not usually related to poor technique. Skull fracture is rare and most need no treatment unless depressed, when surgical elevation may be indicated. Vacuum delivery may result in retinal haemorrhages, haematoma confined to one of the skull bones and neonatal jaundice. Severe scalp lacerations imply poor technique and are fortunately rare. Subgaleal haemorrhage may cause minor or severe morbidity and rarely mortality [18] . In reviewing morbidity associated with IVD, it is important to remember that the alternative option of second‐stage CS is also associated with increased morbidity for both mother and baby. Safe practice: sequential intrumentation and trial of instrumental delivery For all IVDs, the procedure should be abandoned if there is ‘no evidence of progressive descent with moderate traction during each contraction, or where delivery is not imminent following three contractions of a correctly applied instrument by an experienced operator’ [11] . Sequential instrumentation is associated with increased neonatal morbidity and the decision to proceed must take into account the relative risks of delivery by second‐stage CS from deep in the pelvis. It can be difficult to judge whether to proceed with IVD, especially in cases with mid‐cavity malposition at the level of the ischial spines. In such cases a trial of instrumental delivery should be undertaken in theatre under regional anaesthesia, with the full theatre team and neonatal practitioner present. The estimated incidence of trial of instrumental delivery is 2–5%. It is vital to maintain awareness of the situation, with a clear willingness to abandon the attempt if progress is not as expected, proceeding immediately to CS. The couple should be advised of this strategy and appropriate consent obtained prior to the procedure, which should be undertaken by the most senior obstetrician available. In the presence of fetal compromise, it is prudent to consider delivery by emergency CS, rather than proceeding with a potentially difficult IVD. Paired cord blood samples should be taken and results recorded after every attempted IVD. Contemporary developments in IVD New methods are being developed to achieve IVD and include disposable plastic forceps with the ability to measure traction force (see http://www.medipex.co.uk/success‐stories/pro‐nata‐yorkshire‐obstetric‐forceps/ and Fig. 26.10 ) and the Odon device where traction is applied using a plastic bag placed around the fetal head and neck. This device is undergoing trials led by the World Health Organization (see http://www.who.int/reproductivehealth/topics/maternal_perinatal/odon_device/en/ ). Fig. 26.10 Pro‐Nata Yorkshire obstetric forceps. Reproduced with permission of Mark Jessup.

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Vertex Presentation: How does it affect your labor & delivery?

Medically Reviewed by: Dr. Veena Shinde (M.D, D.G.O,  PG – Assisted Reproductive Technology (ART) from Warick, UK) Mumbai, India

• >> Post Created: February 11, 2022
• >> Last Updated: April 4, 2024

Vertex Position - Table of Contents

As you approach the due date for your baby’s delivery, the excitement and apprehensions are at their peak! What probably adds to the anxieties are the medical terms describing the baby, its ‘position’ and ‘presentation.’ Let’s strike that out from the list now!

In simple words, ‘ position ’ of the baby is always in reference to the mother ; on what side of the mother’s pelvis does the baby lean more (left or right) and if the baby is facing the mother’s spine or belly (anterior or posterior) – for eg.: Left Occiput Anterior , Right Occiput Anterior , Right Occiput Posterior and so on.

On the other hand, ‘ presentation’ is the body part of baby (head, shoulder, feet, and buttocks) that will enter the mother’s pelvic region first at the beginning of labor.

As ‘ presentation’ depends on the ‘ position’ of the baby, the terms cannot be used interchangeably, which is often mistakenly done. If you are told by your doctor that your baby is in a head-down position , which means its head will enter the pelvic region first , then it means the baby is in ‘vertex’ presentation or even sometimes loosely referred to as vertex position of baby though its conceptually incorrect however it means the same.

With this article, we aim to explain how exactly vertex presentation affects your labor and delivery.

Understanding Vertex Presentation

If your baby is in the head-down position by the third trimester, then you are one of the 95% mothers who have a vertex baby or a vertex delivery. When the baby enters the birth canal head first, then the top part of the head is called the ‘vertex.’

In exact medical terms, we give you the definition of vertex presentation by the American College of Obstetrics and Gynecologists (ACOG) – “a fetal presentation where the head is presenting first in the pelvic inlet.”

Besides vertex presentation (also sometimes referred to as vertex position of baby or vertex fetal position also), the other occasional presentations (non-vertex presentations) include –

• Breech – baby’s feet or buttocks are down and first to enter the mother’s pelvic region. Head is near the mother’s ribs
• Transverse – baby’s shoulder, arm or even the trunk are the first to enter the pelvis, as the baby is laying on the side and not in a vertical position 

It is common that babies turn to a particular position (hence, affecting the presentation) by 34 -36 weeks of pregnancy. Nevertheless, some babies have ‘unstable lies’ ; – wherein the baby keeps changing positions towards the end of the pregnancy and not remaining in any one position for long.

Should you be worried if the baby is in vertex presentation?

Absolutely not! The vertex presentation is not only the most common, but also the best for a smooth delivery. In fact, the chances of a vaginal delivery are better if you have a vertex fetal position.

By 36 weeks into pregnancy, about 95% of the babies position themselves to have the vertex presentation. However, if your baby hasn’t come into the vertex fetal position by this time, then you can talk to your doctor about the options.

You may be suggested a cephalic version procedure   also known as the version procedure /external cephalic version (ECV procedure) – which is used to turn the baby/ fetus from a malpresentation – like breech, oblique or transverse (which occur just about 3-4% times) to the cephalic position (head down).

This is how your doctor will try to turn your baby manually by pushing on your belly to get the baby into the vertex presentation. But it is necessary for you to know that this procedure does involve some risk and is successful only 60-70% of the time.

Continue reading below ↓

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Risks of vertex position of baby: can there be any complications for the baby in the vertex presentation.

As discussed above, the vertex fetal position/presentation is the best for labor and delivery, but there can be some complications as the baby makes its way through the birth canal. One such complication can arise if the baby is on the larger side. The baby can face difficulty while passing through the birth canal even if it is in the head-down position because of the size.

Babies who weigh over 9 to 10 pounds are called ‘ macrosomic’ or even referred to as fetal macrosomia , and they are at a higher risk of getting their shoulders stuck in the birth canal during delivery, despite being in the head-down position.

In such cases, to avoid birth trauma for the baby, the American College of Obstetricians and Gynecologists (ACOG) suggests that cesarean deliveries should be limited to estimated fetal weights of at least 11 pounds in women without diabetes and about 9 pounds in women with diabetes.

In case of fetal macrosomia, your doctor will monitor your pregnancy more often and work out a particular birth plan for you subject to your age (mothers age) and size of your baby.

How will I deliver a baby in the vertex fetal position?

Even unborn human babies can astonish you if you observe the way they make their way through the birth canal during delivery.

A vertex baby may be in the optimal position ( head-down first in pelvis) for labor and delivery, but it does its own twisting and turning while passing through the birth canal to fit through. In humans, unlike other mammals, the ratio of the baby’s head to the space in the birth canal is quite limited.

The baby has to flex and turn its head in different positions to fit through and ultimately arrive in this world. And it does so successfully! It is a wonder how they know how to do this so naturally.

And to answer the question ‘how will I deliver a baby in the vertex position?’ – Simply NATURALLY i.e. vaginal delivery. Don’t worry, follow your doctor’s instructions, do your breathing and PUSH.

FAQs to keep ready: How can my doctor help me prepare as I approach my due date?

As your due date nears, apart from bodily discomfort, you may experience nervousness about the big day. Your doctor can help by clearing your doubts and putting you at ease. You can ask them the following questions to understand the process better.

Q1) How will I know if my baby is in vertex fetal position?

A doctor can confidently tell you whether or not your baby is in the vertex presentation. Many medical professionals will be able to determine your baby’s position merely by using their hands; this is called ‘Leopold’s maneuvers.’

However, in case they aren’t very confident about the baby’s position even after this, then an ultrasound can confirm the exact position of the baby.

You can also understand this through belly mapping . You are sure to feel the kicks towards the top of your stomach and head (distinct hard circular feel) towards your pelvis. 

Q2)Is there any risk of my vertex baby turning and changing positions?

Yes, in case of some women, the baby who has a vertex presentation may turn at the last moment.

What may cause this? Women who have extra amniotic fluid (polyhydramnios) have increased chances of a vertex baby turning into a breech baby at the last minute.

Discuss this with your doctor to understand what are the chances this might happen to you and what all you can do to keep the baby in the vertex presentation for delivery.

Q3) Is there need to be worried if my baby has a breech presentation?

Not really! There are loads of exercises which you which can help you get your baby in the right position.

Then there are the ECV (external cephalic version) procedure which can help in changing the position of your baby into the desired vertex position. Speak with your doctor.

Having a baby in breech position just before labor will require you to have a C-section . Let your doctor guide you. But there is nothing to worry about.

Q4) What may cause babies to come into breech position?

A few circumstances may cause the baby to come into breech position even after 36 weeks into pregnancy.

• If you are carrying twins or multiple babies , in which case there is limited space for each baby to move around.
• Low levels of amniotic fluid which restricts the free movement of the baby or even high levels of amniotic fluid that does not permit the baby to remain in any one position.
• If there are abnormalities in the uterus or other conditions like low-lying placenta or large fibroids in the lower part of the uterus.

Chances of breech babies are higher in births that are pre-term as the baby does not get enough time to flip into a head-down position – cephalic position – vertex presentation (vertex position of baby/ vertex fetal position).

Q5) Can a baby turn from breech position to vertex presentation?

Yes, a baby can turn from a breech position to vertex position / vertex fetal position over time with exercises and sometimes through ECV.

If an ultrasound has confirmed you have a breech baby, then you can do the following to turn it to a vertex baby. Try the following –

• Do not underestimate the wonders of daily walks of about 45-60 mins when it comes to bringing your baby in vertex presentation from breech presentation.
• Talk to your doctor about certain exercises that can help turn your baby in the head-down position. Exercises like ‘ high bridge’ or ‘cat and camel’ can help here. We recommend you to learn and try this only in the presence of a professional.
• External Cephalic Version (ECV ) is a way to manually maneuver the baby to vertex presentation. It is done with the help of an ultrasound and generally after 36 weeks into pregnancy. However, it has the success rate of just 50%. Discuss the risks, if any, with your gynecologist before opting for this procedure.

There are a couple of other unscientific methods that may not be safe to try –

• Light : Placing a torch near your vagina may guide the baby toward the light, and hence, get it in the vertex presentation.
• Music : Playing music near your belly’s bottom may urge the baby to move itself in the head-down position.

Q6) What all can I do to ensure I have a healthy delivery?

A healthy delivery requires the mother to be active, eating well, and staying happy. For any apprehensions regarding labor and delivery, do not hesitate to talk to your doctor and clarify your doubts.

Your doctor can help you understand your baby’s position and presentation, and then based on that they can plan your delivery to ensure your baby’s birth will happen in the safest possible way.

Try and maintain a healthy lifestyle which will also help in overall of your child and placenta health .

Key Takeaway

Yes, vertex presentation or vertex position of baby and vertex delivery are very common, normal, safe, and the best for labor and delivery of the baby. There is probability of complications sometimes, but that is only subject to certain conditions that we discussed above.

However, understand that any other baby position is also safe. The only thing with other positions and presentations is that the chances of a cesarean delivery goes up. Nevertheless, know what matters at the end of it all is a happy and healthy baby in your arms!

Happy pregnancy!

Khushboo Kirale

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Abnormal Fetal lie, Malpresentation and Malposition

Original Author(s): Anna Mcclune Last updated: 1st December 2018 Revisions: 12

• 1 Definitions
• 2 Risk Factors
• 3.2 Presentation
• 3.3 Position
• 4 Investigations
• 5.1 Abnormal Fetal Lie
• 5.2 Malpresentation
• 5.3 Malposition

The lie, presentation and position of a fetus are important during labour and delivery.

In this article, we will look at the risk factors, examination and management of abnormal fetal lie, malpresentation and malposition.

Definitions

• Longitudinal, transverse or oblique
• Cephalic vertex presentation is the most common and is considered the safest
• Other presentations include breech, shoulder, face and brow
• Usually the fetal head engages in the occipito-anterior position (the fetal occiput facing anteriorly) – this is ideal for birth
• Other positions include occipito-posterior and occipito-transverse.

Note: Breech presentation is the most common malpresentation, and is covered in detail here .

Fig 1 – The two most common fetal presentations: cephalic and breech.

Risk Factors

The risk factors for abnormal fetal lie, malpresentation and malposition include:

• Multiple pregnancy
• Uterine abnormalities (e.g fibroids, partial septate uterus)
• Fetal abnormalities
• Placenta praevia
• Primiparity

Identifying Fetal Lie, Presentation and Position

The fetal lie and presentation can usually be identified via abdominal examination. The fetal position is ascertained by vaginal examination.

For more information on the obstetric examination, see here .

• Face the patient’s head
• Place your hands on either side of the uterus and gently apply pressure; one side will feel fuller and firmer – this is the back, and fetal limbs may feel ‘knobbly’ on the opposite side

Presentation

• Palpate the lower uterus (above the symphysis pubis) with the fingers of both hands; the head feels hard and round (cephalic) and the bottom feels soft and triangular (breech)
• You may be able to gently push the fetal head from side to side

The fetal lie and presentation may not be possible to identify if the mother has a high BMI, if she has not emptied her bladder, if the fetus is small or if there is polyhydramnios .

During labour, vaginal examination is used to assess the position of the fetal head (in a cephalic vertex presentation). The landmarks of the fetal head, including the anterior and posterior fontanelles, indicate the position.

Fig 2 – Assessing fetal lie and presentation.

Investigations

Any suspected abnormal fetal lie or malpresentation should be confirmed by an ultrasound scan . This could also demonstrate predisposing uterine or fetal abnormalities.

Abnormal Fetal Lie

If the fetal lie is abnormal, an external cephalic version (ECV) can be attempted – ideally between 36 and 38 weeks gestation.

ECV is the manipulation of the fetus to a cephalic presentation through the maternal abdomen.

It has an approximate success rate of 50% in primiparous women and 60% in multiparous women. Only 8% of breech presentations will spontaneously revert to cephalic in primiparous women over 36 weeks gestation.

Complications of ECV are rare but include fetal distress , premature rupture of membranes, antepartum haemorrhage (APH) and placental abruption. The risk of an emergency caesarean section (C-section) within 24 hours is around 1 in 200.

ECV is contraindicated in women with a recent APH, ruptured membranes, uterine abnormalities or a previous C-section .

Fig 3 – External cephalic version.

Malpresentation

The management of malpresentation is dependent on the presentation.

• Breech – attempt ECV before labour, vaginal breech delivery or C-section
• Brow – a C-section is necessary
• If the chin is anterior (mento-anterior) a normal labour is possible; however, it is likely to be prolonged and there is an increased risk of a C-section being required
• If the chin is posterior (mento-posterior) then a C-section is necessary
• Shoulder – a C-section is necessary

Malposition

90% of malpositions spontaneously rotate to occipito-anterior as labour progresses. If the fetal head does not rotate, rotation and operative vaginal delivery can be attempted. Alternatively a C-section can be performed.

• Usually the fetal head engages in the occipito-anterior position (the fetal occiput facing anteriorly) - this is ideal for birth

If the fetal lie is abnormal, an external cephalic version (ECV) can be attempted - ideally between 36 and 38 weeks gestation.

• Breech - attempt ECV before labour, vaginal breech delivery or C-section

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Fetal Malpresentation and Malposition

Fetal presentation describes which part of the fetus will enter through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first, while position is the orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment of the fetus compared to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy . Presentations include vertex (the fetal occiput will present through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first), face, brow, shoulder, and breech. If a fetal limb is presenting next to the presenting part (e.g., the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy is next to the head), this is known as a compound presentation. Malpresentation refers to any presentation other than vertex, with the most common being breech presentations. Vaginal delivery of a breech infant increases the risk for head entrapment and hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage , so, especially in the United States, mothers are generally offered a procedure to help manually rotate the baby to a head-down position instead (known as an external cephalic version) or a planned cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery .

Last updated: Feb 14, 2023

Fetal Lie and Presentation

Presenting diameter, management of cephalic and compound presentations, risks and management of breech and transverse presentations.

Share this concept:

• The “presenting part” refers to the part of the baby that will come through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first. 
• The position refers to how that body part (and thus the baby) is oriented within the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy . 
• The uterine fundus Fundus The superior portion of the body of the stomach above the level of the cardiac notch. Stomach: Anatomy is typically roomier, so babies tend to orient themselves head down so that their body and limbs occupy the larger portion of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .

Clinical relevance

• The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy has a diameter of about 10 cm, through which the fetus must pass.
• The presentation and position of the fetus will determine how wide the fetus is (known as the “presenting fetal diameter”) as it attempts to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
• Certain presentation/positions are more difficult (or even impossible) to pass through the pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy because of their large presenting diameter.
• Knowledge of the presentation and position are required to safely manage labor and delivery.

Risk factors for fetal malpresentation

• Multiparity (which can result in lax abdominal walls)
• Multiple gestations (e.g., twins)
• Prematurity Prematurity Neonatal Respiratory Distress Syndrome
• Uterine abnormalities (e.g., leiomyomas, uterine septa)
• Narrow pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shapes
• Fetal anomalies (e.g., hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage )
• Placental anomalies (e.g.,   placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , in which the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity covers the internal cervical os)
• Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios (too much fluid)
• Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios (not enough fluid)
• Malpresentation in a previous pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care

Epidemiology

Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency rates for different malpresentations at term:

• Vertex presentation, occiput posterior position: 1 in 19 deliveries
• Breech presentation: 1 in 33 deliveries
• Face presentation: 1 in 600–800 deliveries
• Transverse lie: 1 in 833 deliveries
• Compound presentation: 1 in 1500 deliveries 

Related videos

Fetal lie is how the long axis of the fetus is oriented in relation to the mother. Possible lies include:

• Longitudinal: fetus and mother have the same vertical axis (their spines are parallel).
• Transverse: fetal vertical axis is at a 90-degree angle to mother’s vertical axis (their spines are perpendicular).
• Oblique: fetal vertical axis is at a 45-degree angle to mother’s vertical axis (unstable, and will resolve to longitudinal or transverse during labor).

Presentation

Presentation describes which body part of the fetus will pass through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first. Presentations include:

• Cephalic: head down
• Breech: bottom/feet down
• Transverse presentation: shoulder 
• Compound presentation: an extremity presents alongside the primary presenting part

Cephalic presentations

Cephalic presentations can be categorized as:

• Vertex presentation: chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma flexed, with the occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy fontanel as the presenting part
• Face presentation
• Brow presentation: forehead Forehead The part of the face above the eyes. Melasma is the presenting part

Vertex presentation

Face presentation (mentum anterior position)

Brow presentation (mentum posterior position)

Breech presentations

Breech presentations can be categorized as:

• Frank breech: bottom down, legs extended (50%–70%) 
• Complete breech: bottom down, hips and knees both flexed
• Incomplete breech: 1 or both hips not completely flexed
• Footling breech: feet down

Breech presentations: Frank (bottom down, legs extended), complete (bottom down, hips and knees both flexed), and footling (feet down) breech presentations

Transverse and compound presentations

• Uncommon, but when they occur, the presenting fetal part is the shoulder.
• If the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy begins dilating, the arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy may prolapse through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy .
• In compound presentations, the most common situation is a hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy or arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy presenting with the head.

Shoulder presentation (transverse lie)

Neglected shoulder presentation resulting in arm prolapse during labor

Vertex presentation with a compound hand

Fetal malpresentation

• Any presentation other than vertex
• Clinically, this means breech, face, brow, and shoulder presentations.

Position describes the relation of the fetal presenting part to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Vertex positions

Positions for vertex presentations describe the position of the fetal occiput .

• Identified on cervical exam as the area in the midline between the anterior and posterior fontanelles Fontanelles Physical Examination of the Newborn
• Anterior, posterior, or transverse in relation to the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy
• Being on the maternal right or left
• Right or left occiput anterior
• Right or left occiput posterior
• Right or left occiput transverse
• Direct occiput anterior or posterior
• The most common positions (and easiest for vaginal delivery) are occiput anterior.

Overview of different vertex positions LOA: left occiput anterior LOP: left occiput posterior LOT: left occiput transverse OA occiput anterior OP: occiput posterior ROA: right occiput anterior ROP: right occiput posterior ROT: right occiput transverse

Face and brow positions

Positions for face and brow presentations describe the position of the chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma .

• The chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma is referred to as the mentum.
• Right or left mentum anterior
• Right or left mentum posterior
• Right or left mentum transverse
• Direct mentum anterior or posterior

Face presentation (mentum posterior position)

Breech and shoulder positions

• Positions for breech presentations describe the position of the sacrum Sacrum Five fused vertebrae forming a triangle-shaped structure at the back of the pelvis. It articulates superiorly with the lumbar vertebrae, inferiorly with the coccyx, and anteriorly with the ilium of the pelvis. The sacrum strengthens and stabilizes the pelvis. Vertebral Column: Anatomy . Similar to other presentations, they include anterior, posterior, and transverse and right, left, and direct.
• Dorso-superior (back up)
• Dorso-inferior (back down)

Dorso-inferior shoulder presentation

Dorso-superior shoulder presentation

Attitude and asynclitism

• Attitude: amount of flexion Flexion Examination of the Upper Limbs or extension Extension Examination of the Upper Limbs of the fetal head
• Lateral deflection of the sagittal Sagittal Computed Tomography (CT) suture to 1 side or the other
• Mild degrees of asynclitism are normal.
• More severe asynclitism increases the presenting fetal diameter and makes it more difficult for the fetal head to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Fetal malposition

• Commonly refers to any position other than right occiput anterior, left occiput anterior, or direct occiput anterior
• All nonvertex presentations are also malpositioned.
• The terms fetal malpresentation and fetal malposition are often used interchangeably.
• The presenting diameter refers to the width of the presenting part.
• The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy is about 10 cm at its narrowest point; the infant must orient itself so that it can fit through.
• Most commonly, the infant will move into a cephalic, vertex presentation, in 1 of the occiput anterior positions → presents the narrowest diameter
• Vertex presentation: suboccipitobregmatic diameter, approximately 9.5 cm
• Vertex presentation with deflexed head: occipitofrontal diameter, approximately 11.5 cm
• Brow presentation: occipitomental diameter, approximately 13 cm
• Face presentation: submentobregmatic diameter, approximately 9.5 cm

Diameters of the fetal head

Comparison of presentation, attitude, and presenting diameter

How to establish lie, presentation, and position

Delivery is managed differently depending on the presentation and position of the infant. This information can be established in several different ways:

Leopold’s maneuvers

Ultrasonography.

• Cervical examination
• Techniques using abdominal palpation Abdominal Palpation Abdominal Examination to determine the presentation of the fetus
• The fetal head will be hard and round.
• The lower body will be bulkier, nodular, and mobile.
• The back will be hard and smooth.
• The other side (anterior surface of the fetus) will be filled with irregular, mobile fetal parts.
• Experienced providers can also estimate the fetal weight using these maneuvers.
• Bedside abdominal ultrasonography can easily identify the fetal head and its orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment .
• Quick bedside ultrasonography Bedside Ultrasonography ACES and RUSH: Resuscitation Ultrasound Protocols on admission to labor and delivery to assess fetal presentation is considered standard of care Standard of care The minimum acceptable patient care, based on statutes, court decisions, policies, or professional guidelines. Malpractice .
• The fetal head will typically encompass the entire window and appear like a large white circle (the fetal skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy ).
• Identification Identification Defense Mechanisms of the eyes can help determine position.
• It is quick and easy to perform and presents minimal risk to mother and infant.
• Allowing mothers to labor with infants in a noncephalic presentation significantly increases the risks to both of them.

Suprapubic bedside ultrasound showing the large white circle of the fetal skull, confirming a cephalic presentation F: fetal falx

Vaginal and cervical examination

• As the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy dilates, the fetal fontanelles Fontanelles Physical Examination of the Newborn can be directly palpated.
• Identifying the location of the fetal fontanelles Fontanelles Physical Examination of the Newborn allows the practitioner to establish the position.
• Insert 1–2 fingers through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy posteriorly.
• Sweep fingers along the fetal head moving anteriorly.
• This maneuver allows for identification Identification Defense Mechanisms of the sagittal Sagittal Computed Tomography (CT) suture.
• The fontanelles Fontanelles Physical Examination of the Newborn are then identified by moving along the sagittal Sagittal Computed Tomography (CT) suture.

Vertex presentations

• Expectant management
• All have high chances of successful vaginal delivery.

Compound presentations

• Observation when labor is progressing normally (many compound presentations will resolve spontaneously intrapartum).
• Can attempt to gently pinch the compound extremity trying to provoke the fetus into withdrawing the part (no good quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement evidence, but unlikely to be harmful)
• Can attempt to manually replace the compound extremity
• If labor is prolonged and the compound part remains, cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery (CD) should be performed.
• Prolonged labor
• Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse
• Increased maternal morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status from lacerations
• Ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage of the compound part

Brow presentations

• The majority spontaneously convert to a vertex presentation.
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required if labor is prolonged.

Face presentations

• Management depends on the position.
• Can be delivered vaginally by an experienced provider
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required.
• Head is fully extended and unable to pass through the birth canal Birth canal Pelvis: Anatomy .
• Normally, the fetal head flexes as it passes under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types ; however, this is impossible in an MP position.
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery is always required (unless the infant spontaneously rotates to a mentum anterior (MA) position).

There are 3 primary options for managing breech presentations: performing CD, attempting an external cephalic version to manually rotate the baby into a vertex presentation for attempted vaginal delivery, or a planned vaginal breech delivery (which is generally not done in the United States).

Natural history of breech presentations

Most infants will spontaneously rotate to a vertex presentation as the pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care progresses. At different gestational ages, the prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency of breech presentations is:

• < 28 weeks: 20%–25%
• 32 weeks: 10%–15%
• Term (> 37 weeks): 3% 
• Spontaneous version is possible even at > 40 weeks.
• Flexed fetal legs
• Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios
• Longer umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity
• Lack of fetal/uterine anomalies
• Multiparity

Fetal risks associated with breech presentations

The following risks are associated with breech presentations in utero, regardless of mode of delivery:

• ↑ Association with congenital Congenital Chorioretinitis malformations
• Torticollis Torticollis A symptom, not a disease, of a twisted neck. In most instances, the head is tipped toward one side and the chin rotated toward the other. The involuntary muscle contractions in the neck region of patients with torticollis can be due to congenital defects, trauma, inflammation, tumors, and neurological or other factors. Cranial Nerve Palsies
• Developmental hip dysplasia 

Fetal risks associated with vaginal breech delivery

The primary risk of a vaginal breech delivery is fetal head entrapment:

• The fetal body delivers, but the head remains trapped in the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .
• Causes compression Compression Blunt Chest Trauma of the umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity running past the head (between the delivered umbilicus and the undelivered placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity ) 
• Leads to hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage until head is delivered → ↑ risk of fetal death
• The cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy may not be fully dilated enough to accommodate the head.
• The fetal head may not fit through the bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
• The mother’s expulsive efforts are unable to quickly deliver the head.
• Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse during labor → requires emergent CD
• Birth injuries to the fetus (e.g., brachial plexus Brachial Plexus The large network of nerve fibers which distributes the innervation of the upper extremity. The brachial plexus extends from the neck into the axilla. In humans, the nerves of the plexus usually originate from the lower cervical and the first thoracic spinal cord segments (c5-c8 and T1), but variations are not uncommon. Peripheral Nerve Injuries in the Cervicothoracic Region injury)

Vaginal breech delivery

Vaginal breech deliveries for singleton gestations may be considered for certain low-risk women if vaginal delivery is strongly desired by the mother. In contrast, vaginal breech deliveries are done frequently for breech 2nd twins; the procedure is known as a breech extraction.

• Mothers must be fully counseled on risks.
• Mothers and infants should be monitored throughout labor with continuous electronic fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology (FHR) and tocometry monitors.
• Mothers should understand that a CD will be recommended if there are signs of fetal distress or prolonged labor.
• Avoid artificial rupture of membranes to ↓ risk of cord prolapse.
• Frank or complete breech presentation with no hyperextension of the fetal head on ultrasonography
• No contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation to a vaginal birth
• No prior CDs
• Prior successful vaginal deliveries (i.e., multiparity)
• Gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care ≥ 36 weeks
• Spontaneous labor
• Normal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shown on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
• Estimated fetal weight Estimated Fetal Weight Obstetric Imaging between approximately 2500 and 3500 grams (exact range varies based on clinician Clinician A physician, nurse practitioner, physician assistant, or another health professional who is directly involved in patient care and has a professional relationship with patients. Clinician–Patient Relationship )
• Immediately after delivery of the 1st twin in the cephalic presentation, the physician reaches up into the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy , manually grabs the infant’s legs, and gently guides them down through the birth canal Birth canal Pelvis: Anatomy while the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy is still fully dilated.
• ↓ Risk of head entrapment compared to singleton vaginal breech deliveries

External cephalic version

An external cephalic version (ECV) is a procedure in which the physician attempts to manually rotate the fetus from a breech to a cephalic presentation by pushing on the maternal abdomen.

• Approximately 50%–60% (higher in multiparous Multiparous A woman with prior deliveries Normal and Abnormal Labor than in nulliparous women) 
• 97% of infants remained cephalic at birth.
• 86% delivered vaginally.
• Women who are candidates for ECV should be counseled on their options to attempt an ECV, or they may simply elect to schedule a CD.
• Infant is full term in case emergent CD is required because of complications from the procedure (e.g., placental abruption Placental Abruption Premature separation of the normally implanted placenta from the uterus. Signs of varying degree of severity include uterine bleeding, uterine muscle hypertonia, and fetal distress or fetal death. Antepartum Hemorrhage ).
• Better ratio of infant size to fluid level than later in pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
• Allows infant more time for spontaneous version than if the procedure was done earlier
• After a successful version, the mother can await spontaneous labor or be induced immediately, depending on the situation.
• There is still a chance that the infant may spontaneously rotate between the failed ECV and the planned CD date; therefore, presentation should always be checked immediately prior to CD.
• Another contraindication for a vaginal delivery (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities )
• Severe oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios
• Nonreassuring fetal monitoring Fetal monitoring The primary goals of antepartum testing and monitoring are to assess fetal well-being, identify treatable situations that may cause complications, and evaluate for chromosomal abnormalities. These tests are divided into screening tests (which include cell-free DNA testing, serum analyte testing, and nuchal translucency measurements), and diagnostic tests, which provide a definitive diagnosis of aneuploidy and include chorionic villus sampling (CVS) and amniocentesis. Antepartum Testing and Monitoring prior to the procedure
• A hyperextended fetal head
• Significant fetal or uterine anomalies
• Leads to fetal and maternal hemorrhage
• An immediate CD is required.
• If the version was successful, labor should be induced immediately.
• If the version was unsuccessful, the mother should undergo immediate CD.
• Cord prolapse: can occur with PROM PROM Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, refers to the rupture of the amniotic sac before the onset of labor. Prelabor rupture of membranes may occur in term or preterm pregnancies. Prelabor Rupture of Membranes and requires immediate/emergent CD.
• Common during the procedure, but typically resolves shortly after pressure on the abdomen is released.
• If distress persists, the mother should undergo an immediate CD.

Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery

• Scheduled at 39 weeks’ gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care (WGA) if the infant is known to be in the breech presentation.
• Alternative option to attempting ECV
• Postpartum hemorrhage Postpartum hemorrhage Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Postpartum Hemorrhage
• Postpartum endomyometritis
• Maternal injury
• Longer recovery time postpartum
• Complications in future pregnancies (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , placenta accreta Placenta Accreta Abnormal placentation in which all or parts of the placenta are attached directly to the myometrium due to a complete or partial absence of decidua. It is associated with postpartum hemorrhage because of the failure of placental separation. Placental Abnormalities , uterine rupture Uterine Rupture A complete separation or tear in the wall of the uterus with or without expulsion of the fetus. It may be due to injuries, multiple pregnancies, large fetus, previous scarring, or obstruction. Antepartum Hemorrhage )
• Maternal request (mother declines ECV attempt)
• ECV contraindicated
• ECV unsuccessful
• Fetal distress during labor

Management of transverse presentations

• As with breech presentations, mothers may be offered an attempt at ECV or a CD.
• Unlike breech presentations, vaginal transverse delivery is always contraindicated.
• Hofmeyr, G.J. (2021). Overview of breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/overview-of-breech-presentation  
• Hofmeyr, G.J. (2021). Delivery of the singleton fetus in breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/delivery-of-the-singleton-fetus-in-breech-presentation  
• Hofmeyr, G.J. (2021). External cephalic version. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/external-cephalic-version  
• Julien, S., and Galerneau, F. (2021). Face and brow presentations in labor. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/face-and-brow-presentations-in-labor  
• Strauss, R.A., Herrera, C.A. (2021). Transverse fetal lie. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/transverse-fetal-lie  
• Barth, W.H. (2021). Compound fetal presentation. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/compound-fetal-presentation  
• Cunningham, F. G., Leveno, K. J., et al. (2010). Williams Obstetrics, 23rd ed., pp. 374‒382. 

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Vertex Presentation : Types, Positions, Complications and Risks

Do not ignore your symptoms!

Find out what could be causing them

Overview 

When babies are about to enter the world, they are either in a vertex, breech, or transverse position. A vertex position means the baby is head-down in the pelvic region, which is the position a baby is required to be during vaginal delivery. 

This blog talks about the vertex position, complications, and the other types of positions the baby can be during delivery. 

What is the vertex position? 

As mentioned earlier, a vertex position is a baby’s position during vaginal delivery. The baby moves into the vertex position  between the 33 rd – 36 th week of pregnancy. In this position, the baby’s head comes out first through the vagina during delivery. However, it is vital to know that the baby can present with other positions like breech (feet-first position) or transverse (lying sideways) position. In such cases, the healthcare provider may suggest alternate birth plans to deliver the baby safely.   

How is a baby delivered in the vertex position?  

When a baby is in a vertex position, it moves through the birth canal and comes out through the vagina. Unlike other mammals that have wider birth canals, humans have smaller ones. Due to the tight space in the birth canal, the baby tends to flex their heads in different ways to fit into the area and enter the world. However, the chances of the baby changing position at the last minute reduce drastically when the baby’s head fits inside the birth canal. The baby can switch to a vertex position anytime during delivery even if it is in a breech or transverse position.

When to seek medical advice?

A pregnant woman can seek medical advice to clear any doubts or clarifications.

What are the other positions a baby may lie in the womb?  

As already mentioned, unborn babies may also assume breech or transverse positions in the womb. The following gives a detailed explanation of both.

Breech Position

In this position, the babies lie in the womb pointing their feet or buttocks toward the vagina of the mother. If the baby stays in a breech position even after 36 weeks of pregnancy, the healthcare provider may try External Cephalic Version (ECV) on the mother. ECV refers to external pressure on the belly to change the baby’s position to a vertex. This procedure is painful for the mother, but it is the safest way to keep the baby in place. In almost 50% of the cases, ECV works and assists the baby in moving into a vertex position. 

In case of vaginal bleeding , the irregular heartbeat of the baby, broken water, or multiple pregnancies, ECV is not recommended. Also, ECV should not be performed if the baby is bigger or smaller than usual, if the placenta is low or if the mother develops high blood pressure and organ damage. The healthcare provider may recommend C-section to deliver the baby in such cases. 

Transverse Position

The baby is lying across the uterus during delivery. The doctors may recommend an ECV procedure. If ECV fails, the healthcare provider may deliver the baby through a C-section .

Can complications happen even when the baby is in the vertex position? 

Even though the vertex position is the correct way a baby should lie during delivery, there are chances of complications. If the baby weighs more than 4.5 kg, it becomes challenging for the baby to manoeuvre out of the birth canal. The shoulders of heavy babies may face trouble moving down the canal. For such babies, doctors regularly conduct checks and are extra cautious during prenatal visits and at the time of birth. For babies above 5 kg, they may recommend alternate delivery options to avoid trauma for both the baby and the mother.  

What are the risks associated with the Breech and Transverse position of the baby? 

Breech and transverse positions can lead to many complications, such as the following:  

ECV issues : While the healthcare provider performs ECV to shift the baby’s position into a vertex position, it may rupture the amniotic sac or tear the placenta. Sometimes it may change the baby’s heartbeat or may induce early labour.  

Problems with breech birth : In the breech position, the baby isn’t able to push the cervical muscles of the mother to come out. Their shoulders or heads may get stuck or impaled by the mother’s pelvis. Also, the umbilical cord may enter the vagina before the baby, reducing blood and oxygen flow to the baby.    

Conclusion 

Vertex position is the right way a baby should lie in the womb during delivery. It doesn’t mean that vertex position does not cause complications. It is crucial to seek expert advice during pregnancy to clarify doubts and address all concerns.  

Frequently Asked Questions (FAQs)

Will the baby turn after being in a vertex position .

Even when the baby is in the proper vertex position, there are chances of them turning to other positions. Expectant mothers with excess amniotic fluid may be a risk of a vertex-positioned baby suddenly becoming breech. Consult the healthcare provider and ask what can be done about keeping the baby in the proper position until delivery.  

How to know if a pregnant woman is having a vertex-positioned baby? 

All healthcare professionals are trained to feel the baby’s position with their hands. This method is known as Leopold’s moves, and they may help find if the baby has a positioned vertex. An ultrasound test also helps precisely find and confirm the baby’s position.  

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Fetal Positions for Labor and Birth

Knowing your baby's position can you help ease pain and speed up labor

In the last weeks of pregnancy , determining your baby's position can help you manage pain and discomfort. Knowing your baby's position during early labor can help you adjust your own position during labor and possibly even speed up the process.

Right or Left Occiput Anterior

Illustration by JR Bee, Verywell 

Looking at where the baby's head is in the birth canal helps determine the fetal position.The front of a baby's head is referred to as the anterior portion and the back is the posterior portion. There are two different positions called occiput anterior (OA) positions that may occur.

The left occiput anterior (LOA) position is the most common in labor. In this position, the baby's head is slightly off-center in the pelvis with the back of the head toward the mother's left thigh.

The right occiput anterior (ROA) presentation is also common in labor. In this position, the back of the baby is slightly off-center in the pelvis with the back of the head toward the mother's right thigh.

In general, OA positions do not lead to problems or additional pain during labor or birth.  

Right or Left Occiput Transverse

Illustration by JR Bee, Verywell  

When facing out toward the mother's right thigh, the baby is said to be left occiput transverse (LOT). This position is halfway between a posterior and anterior position. If the baby was previously in a posterior position (in either direction), the LOT position indicates positive movement toward an anterior position.

When the baby is facing outward toward the mother's left thigh, the baby is said to be right occiput transverse (ROT). Like the previous presentation, ROT is halfway between a posterior and anterior position. If the baby was previously in a posterior position, ROT is a sign the baby is making a positive move toward an anterior position.

When a baby is in the left occiput transverse position (LOT) or right occiput transverse (ROT) position during labor, it may lead to more pain and a slower progression.

Tips to Reduce Discomfort

There are several labor positions a mother can try to alleviate pain and encourage the baby to continue rotating toward an anterior position, including:

• Pelvic tilts
• Standing and swaying

A doula , labor nurse, midwife , or doctor may have other suggestions for positions.

Right or Left Occiput Posterior

When facing forward, the baby is in the occiput posterior position. If the baby is facing forward and slightly to the left (looking toward the mother's right thigh) it is in the left occiput posterior (LOP) position. This presentation can lead to more back pain (sometimes referred to as " back labor ") and slow progression of labor.

In the right occiput posterior position (ROP), the baby is facing forward and slightly to the right (looking toward the mother's left thigh). This presentation may slow labor and cause more pain.

To help prevent or decrease pain during labor and encourage the baby to move into a better position for delivery, mothers can try a variety of positions, including:

• Hands and knees
• Pelvic rocking

Mothers may try other comfort measures, including:

• Bathtub or shower (water)
• Counter pressure
• Movement (swaying, dancing, sitting on a birth ball )
• Rice socks (heat packs)

How a Doctor Determines Baby's Position

Leopold's maneuvers are a series of hands-on examinations your doctor or midwife will use to help determine your baby's position. During the third trimester , the assessment will be done at most of your prenatal visits.   Knowing the baby's position before labor begins can help you prepare for labor and delivery.

Once labor begins, a nurse, doctor, or midwife will be able to get a more accurate sense of your baby's position by performing a vaginal exam. When your cervix is dilated enough, the practitioner will insert their fingers into the vagina and feel for the suture lines of the baby's skull as it moves down in the birth canal.   It's important to ensure the baby is head down and moving in the right direction.

Labor and delivery may be more complicated if the baby is not in a head-down position, such as in the case of a breech presentation.

How You Can Determine Baby's Position

While exams by health practitioners are an important part of your care, from the prenatal period through labor and delivery, often the best person to assess a baby's position in the pelvis is you. Mothers should pay close attention to how the baby moves and where different movements are felt.

A technique called belly mapping can help mothers ask questions of themselves to assess their baby's movement and get a sense of the position they are in as labor approaches.

For example, the position of your baby's legs can be determined by asking questions about the location and strength of the kicking you feel. The spots where you feel the strongest kicks are most likely where your baby's feet are.

Other landmarks you can feel for include a large, flat plane, which is most likely your baby's back. Sometimes you can feel the baby arching his or her back.

At the top or bottom of the flat plane, you may feel either a hard, round shape (most likely your baby's head) or a soft curve (most likely to be your baby's bottom).

Guittier M, Othenin-Girard V, de Gasquet B, Irion O, Boulvain M. Maternal positioning to correct occiput posterior fetal position during the first stage of labour: a randomised controlled trial .  BJOG: An International Journal of Obstetrics & Gynaecology . 2016;123(13):2199-2207. doi:10.1111/1471-0528.13855

Gizzo S, Di Gangi S, Noventa M, Bacile V, Zambon A, Nardelli G. Women’s Choice of Positions during Labour: Return to the Past or a Modern Way to Give Birth? A Cohort Study in Italy .  Biomed Res Int . 2014;2014:1-7. doi:10.1155/2014/638093

Ahmad A, Webb S, Early B, Sitch A, Khan K, MacArthur C. Association between fetal position at onset of labor and mode of delivery: a prospective cohort study .  Ultrasound in Obstetrics & Gynecology . 2014;43(2):176-182. doi:10.1002/uog.13189

Nishikawa M, Sakakibara H. Effect of nursing intervention program using abdominal palpation of Leopold’s maneuvers on maternal-fetal attachment .  Reprod Health . 2013;10(1). doi:10.1186/1742-4755-10-12

Choi S, Park Y, Lee D, Ko H, Park I, Shin J. Sonographic assessment of fetal occiput position during labor for the prediction of labor dystocia and perinatal outcomes .  The Journal of Maternal-Fetal & Neonatal Medicine . 2016;29(24):3988-3992. doi:10.3109/14767058.2016.1152250

Bamberg C, Deprest J, Sindhwani N et al. Evaluating fetal head dimension changes during labor using open magnetic resonance imaging .  J Perinat Med . 2017;45(3). doi:10.1515/jpm-2016-0005

Gabbe S, Niebyl J, Simpson J et al.  Obstetrics . Philadelphia, Pa.: Elsevier; 2012.

By Robin Elise Weiss, PhD, MPH Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.

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Determining Normal Fetal Situs (Situs Solitus)

One of the first steps in obtaining cardiac views is to determine how the fetus is oriented within the uterus and to determine the right and left side of the abdominal contents versus the right and left side of the heart and thoracic contents.  This is not as easy as it might seem since the fetal left side can be on the maternal right and the opposite can be true.

In summary, situs refers to the right and left orientation of fetal organs.  For example situs solitus is the normal left to right axis arrangement in the fetus with the stomach and spleen on the left side of the body, and the liver and gallbladder on the right side.

Visual Summary of Normal Fetal Situs

Below are steps required to determine situs related to cephalic or breech presentation, and whether the spine or back is up (anterior) or down (posterior).

1.  Determine the lie of the fetus:

A.  Is the fetus head first with the head in front of the ultrasound screen?  This could also be termed cephalic or vertex presentation. B.  Is the fetal feet or bottom first with the head behind the screen?  This could also be termed footling or breech presentation. C.  Determine whether the spine or back is anterior (back up) or posterior (back down).

2.  Obtain a transverse cut of the thorax to demonstrate a 4-chamber view.  The left atrium is nearest the spine and the cardiac axis points to the left.

Detailed Method to Determine Fetal Situs

1.  Define within the uterus the presentation of the fetus (generally vertex or breech; less often the presentation is oblique or transverse.).

2.  Determine whether the fetal spine is parallel or transverse to the maternal spine.  In sagittal view, if the fetal and maternal spine are parallel, the fetus is in longitudinal lie.  When the fetal spine is perpendicular to the maternal spine, the fetus is in a transverse lie.

3.  Determine the position of the fetal left side.  The fetal left side will be as follows: A.  With respect to the maternal abdomen, the fetal left side is anterior and near to the ultrasound transducer. B.  With respect to the posterior uterine wall, the fetal left side is posterior and farthest from the transducer. C.  With respect to the right uterine wall, the fetal left side will be on the maternal right. D.  With respect to the left uterine wall, the fetal left side will be on the maternal left.

4.  Obtain a transverse view of the abdomen and define the fetal stomach which is positioned in the left side of the fetal abdomen.

5.  Obtain a 4-chamber view of the heart by obtaining a transverse view of the thorax.  The left atrium and descending aorta are nearest to the spine and the cardiac axis points to the left.

6.  Finally, ascertain if the stomach and heart are in their correct respective locations, i.e., the stomach is on the left side and the cardiac axis points to the left.

7.  Place a transverse image of the fetal abdomen and heart side by side and validate that the left side of the fetal abdomen (stomach near to the spine) is concordant with the left side of the fetal heart (left atrium and descending aorta near to the spine).  This is done by displaying a side by side comparison of a transverse view through the fetal stomach and a 4-chamber cardiac view.

Above.  Normal ultrasound orientation for situs solitus.

Right Hand Rule of Thumb:  Introduction

In their article “Sonographic definition of the fetal situs,” Bronshtein, Gover, and Zimmer [ 1 ]  describe a “right hand rule of thumb” to define fetal situs during transabdominal scanning, and a “left hand rule of thumb” for transvaginal scanning.

Right Hand Rule of Thumb:  Cephalic, supine, back down

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The palm of the hand is anterior, or represents the ventral or face surface of the fetus.  The fetus is therefore face up, back down, and the thumb points to the fetal left.

Right.   Again, the imaginary fetus is back down with the stomach and cardiac axis pointing to the left.  (Ignore color scheme of fetal heart and vessels.)

Right Hand Rule of Thumb:  Cephalic, prone, back up

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The top of the hand (dorsal surface or prone position) represents back up.

Right.  The imaginary fetus is back up with the stomach and cardiac axis pointing to the fetal left.

Right Hand Rule of Thumb:  Breech, supine, back down

Left.   The sonographer’s right hand represents the fetus with the thumb pointing to the fetal left.  The palm of the sonographer’s hand is anterior, or represents the ventral surface of the fetus.  The fetus is therefore face up, back down, and the thumb points to the fetal left.

Right .  The imaginary fetus is back down with the stomach and cardiac axis pointing to the left.  (Ignore color scheme of fetal heart and vessels).

Right Hand Rule of Thumb:  Breech, prone, back up

Right .  The imaginary fetus is back up with the stomach and cardiac axis pointing to the fetal left side.

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vertex presentation

Medical Definition of vertex presentation

Dictionary entries near vertex presentation, cite this entry.

“Vertex presentation.” Merriam-Webster.com Medical Dictionary , Merriam-Webster, https://www.merriam-webster.com/medical/vertex%20presentation. Accessed 4 Apr. 2024.

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