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INTRODUCTION

Issues related to UTIs or asymptomatic bacteriuria in other populations are discussed in detail elsewhere. (See "Acute simple cystitis in adult and adolescent females" and "Acute simple cystitis in adult and adolescent males" and "Acute complicated urinary tract infection (including pyelonephritis) in adults and adolescents" and "Asymptomatic bacteriuria in adults" and "Catheter-associated urinary tract infection in adults" .)

EPIDEMIOLOGY

Incidence and risk factors  —  The incidence of bacteriuria in pregnant women is approximately the same as that in nonpregnant women; however, recurrent bacteriuria is more common during pregnancy. Additionally, the incidence of pyelonephritis is higher than in the general population, likely as a result of physiologic changes in the urinary tract during pregnancy. (See 'Pathogenesis' below.)

Asymptomatic bacteriuria occurs in 2 to 7 percent of pregnant women [ 1,2 ]. It typically occurs during early pregnancy, with only approximately a quarter of cases identified in the second and third trimesters [ 3 ]. Factors that have been associated with a higher risk of bacteriuria include a history of prior urinary tract infection, pre-existing diabetes mellitus, and low socioeconomic status [ 4,5 ].

Without treatment, as many as 20 to 35 percent of pregnant women with asymptomatic bacteriuria will develop a symptomatic urinary tract infection (UTI), including pyelonephritis, during pregnancy [ 6,7 ]. This risk is reduced by 70 to 80 percent if bacteriuria is eradicated (see 'Rationale for treatment' below). Although a study from the Netherlands suggested a low rate of pyelonephritis among 208 women with untreated asymptomatic bacteriuria (2.4 percent versus 0.6 percent among 4035 women without bacteriuria), this study included only low-risk women with uncomplicated singleton pregnancies without diabetes mellitus or urinary tract abnormalities, and it is uncertain whether these results are generalizable [ 8 ].

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Urinary Tract Infection in Pregnancy

, MD, PhD, University of Texas Health Medical School at Houston, McGovern Medical School

Urinary tract infection Introduction to Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) can be divided into upper and lower tract infections: Upper tract infections involve the kidneys ( pyelonephritis). Lower tract infections involve the bladder... read more (UTI) is common during pregnancy, apparently because of urinary stasis, which results from hormonal ureteral dilation, hormonal ureteral hypoperistalsis, and pressure of the expanding uterus against the ureters. Asymptomatic bacteriuria occurs in about 15% of pregnancies and sometimes progresses to symptomatic cystitis Cystitis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more or pyelonephritis Acute pyelonephritis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more . Frank UTI is not always preceded by asymptomatic bacteriuria.

Asymptomatic bacteriuria, UTI, and pyelonephritis increase risk of

Preterm labor Preterm Labor Labor (regular uterine contractions resulting in cervical change) that begins before 37 weeks gestation is considered preterm. Risk factors include prelabor rupture of membranes, uterine abnormalities... read more

Premature rupture of the membranes Prelabor Rupture of Membranes (PROM) Prelabor rupture of membranes is leakage of amniotic fluid before onset of labor. Diagnosis is clinical. Delivery is recommended when gestational age is ≥ 34 weeks and is generally indicated... read more

Diagnosis of UTI in Pregnancy

Urinalysis and culture

Urinalysis and culture are routinely done at initial evaluation to check for asymptomatic bacteriuria. Diagnosis of symptomatic UTI is not changed by pregnancy.

Treatment of UTI in Pregnancy

Antibacterial drugs such as cephalexin , nitrofurantoin , or trimethoprim /sulfamethoxazole

Proof-of-cure cultures and sometimes suppressive therapy

Antibacterial drug selection is based on individual and local susceptibility and resistance patterns, but good initial empiric choices include the following:

Nitrofurantoin

Trimethoprim /sulfamethoxazole

Nitrofurantoin is contraindicated in pregnant patients at term, during labor and delivery, or when the onset of labor is imminent because hemolytic anemia in the neonate is possible. Pregnant women with G6PD (glucose-6-phosphate dehydrogenase) deficiency should not take nitrofurantoin . Incidence of neonatal jaundice is increased when pregnant women take nitrofurantoin during the last 30 days of pregnancy. Nitrofurantoin should be used during the 1st trimester only when no other alternatives are available.

Trimethoprim /sulfamethoxazole (TMP/SMX) can cause congenital malformations (eg, neural tube defects) and kernicterus in the neonate. Folic acid supplementation may decrease the risk of some congenital malformations. TMP/SMX should be used during the 1st trimester only when no other alternatives are available.

After treatment, proof-of-cure cultures are required.

Women who have pyelonephritis or have had more than one UTI may require suppressive therapy, usually with TMP/SMX (before 34 weeks) or nitrofurantoin , for the rest of the pregnancy.

In women who have bacteriuria with or without UTI or pyelonephritis, urine should be cultured monthly.

Asymptomatic bacteriuria, UTI, and pyelonephritis increase risk of preterm labor and premature rupture of the membranes.

Initially treat with cephalexin , nitrofurantoin , or trimethoprim /sulfamethoxazole.

Obtain proof-of-cure cultures after treatment.

For women who have had pyelonephritis or more than one UTI, consider suppressive therapy, usually with trimethoprim /sulfamethoxazole (before 34 weeks) or nitrofurantoin .

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UTI (urinary tract infection) during pregnancy

What's a UTI?

Why it's common to have a uti in pregnancy, uti symptoms, uti during pregnancy with no symptoms, uti treatment, preventing a uti.

UTIs are urinary tract infections. They're generally caused by bacteria from your skin, vagina, or rectum that enter your urethra and travel upstream. You can have a UTI in any part of your urinary tract, which starts at the kidneys, where urine is made; continues through tubes called ureters down to the bladder, where urine accumulates until you pee; and ends with the urethra, a short tube that carries the urine outside your body.

Here are the most common types of UTIs:

• Cystitis, or bladder infection - This happens when bacteria stop in your bladder and multiply there, causing inflammation and triggering those familiar symptoms. Cystitis is the most common type of UTI.
• Kidney infection - Bacteria may also travel from your bladder up through the ureters to infect one or both kidneys. A kidney infection (also called pyelonephritis) is one of the most common serious medical complications of pregnancy . The infection can spread to your bloodstream and become life-threatening for you. A kidney infection may also have serious consequences for your baby. It increases your risk of preterm labor and having a low-birth-weight baby, and it has been linked to an increased risk of fetal or newborn mortality.
• Asymptomatic bacteriuria - It's possible to have bacteria in your urinary tract and have no symptoms. This is known as asymptomatic bacteriuria. When you're not pregnant, this condition generally doesn't cause problems and often clears on its own. During pregnancy, however, asymptomatic bacteriuria that's left untreated significantly increases your risk of getting a kidney infection and is associated with preterm labor and low birth weight. This is one reason your urine is routinely tested during pregnancy.

Pregnancy increases your risk of all three types of urinary tract infection mentioned above.

Here's why: Higher levels of the hormone progesterone decrease the muscle tone of the ureters (the tubes between the kidneys and the bladder), slowing the flow of urine. Plus, as your uterus enlarges it may compress the ureters, making it that much more difficult for urine to flow through them as quickly and as freely as usual.

Your bladder also loses tone during pregnancy. It becomes more difficult to completely empty your bladder, and your bladder becomes more prone to reflux, a condition where some urine flows back up the ureters toward the kidneys.

The upshot of these changes is that it takes longer for urine to pass through your urinary tract, giving bacteria more time to multiply and take hold before being flushed out, and it also becomes easier for the bacteria to travel up to your kidneys.

What's more, during pregnancy your urine becomes less acidic and more likely to contain glucose, both of which boost the potential for bacterial growth.

Symptoms of a UTI vary from woman to woman. For a bladder infection, they include:

• Pain, discomfort, or burning when urinating and possibly during sex
• Pelvic discomfort or lower abdominal pain (often just above the pubic bone)
• A frequent or uncontrollable urge to pee, even when there's very little urine in the bladder
• Urine that's foul smelling or looks cloudy. (If you see blood in your urine call your doctor or midwife as soon as possible because it may be a sign of other problems.)

Since a frequent urge to pee is common during pregnancy, it may be hard to know for sure whether you have a UTI, especially if your symptoms are mild. If you think you might have an infection, be sure to call your healthcare provider so your urine can be tested.

Symptoms of a possible kidney infection often come on abruptly and commonly include:

• Pain in your lower back or side just under your ribs, on one or both sides, and possibly in your abdomen
• Nausea and vomiting

You may also notice blood or pus in your urine and may have some common UTI symptoms as well. If you have any signs pointing to a possible kidney infection, get medical attention immediately.

Asymptomatic bacteriuria is associated with preterm birth and low birth weight. And if the bacteriuria isn't treated, your chance of developing a kidney infection may be as high as 35 percent. However, with adequate treatment your risk goes down dramatically.

To find out whether there's bacteria in your urinary tract, your practitioner will collect urine at your first prenatal visit and send it to a lab for testing, whether you have symptoms or not. If this initial urine culture is negative, your chances of developing a UTI later in pregnancy are small.

If the culture is positive, you'll be treated with oral antibiotics that are safe to take during pregnancy. Taking the full course of antibiotics, usually for a week, should clear the infection.

After treatment, you'll be tested again to make sure the infection is gone. (If it's not, you'll be retreated using a different antibiotic.) Repeat urine cultures should be done regularly throughout your pregnancy to make sure you don't have another infection. If the bacteriuria recurs, you'll be treated again and likely be put on a continuous low dose of antibiotics for the remainder of your pregnancy to prevent another recurrence.

If you develop a UTI during your pregnancy, you'll be given oral antibiotics. The antibiotics will probably relieve your symptoms within a few days, but it's important to complete the entire course that your caregiver prescribed in order to get rid of all of the bacteria in your urinary tract.

You'll be tested after treatment and periodically during your pregnancy (as well as any time symptoms recur) and retreated if necessary. If you keep getting UTIs, you'll need to take a low dose of antibiotics daily for prevention.

If you develop a kidney infection during pregnancy, you'll be hospitalized and started on intravenous fluid and antibiotics, and you and your baby will be carefully monitored. Your caregivers will be assessing a variety of things, including your temperature, blood pressure, pulse, breathing, and ability to make urine; your baby's heart rate; and whether you have any signs of premature labor.

The length of hospitalization for a kidney infection varies, depending on your situation. If, after an initial 12- to 24-hour assessment, it's clear that you have a mild case, you're responding well to treatment, and preterm labor is not a concern, your caregiver may decide to discharge you from the hospital and switch you to oral antibiotics for the remainder of your treatment.

On the other hand, if you have a severe case, you'll need to remain in the hospital for further treatment and monitoring, and you won't be discharged until 24 to 48 hours after your temperature returns to normal and you no longer have any symptoms.

Once you complete your treatment, you'll be put on a regimen of low-dose antibiotics for the remainder of your pregnancy to help prevent another infection. Without daily suppressive therapy, your risk of getting another kidney infection is very high.

Take these steps to minimize your chances of getting a urinary tract infection:

• Drink plenty of water. Sip throughout the day to keep your urine clear or pale yellow in color – a sign of proper hydration.
• Don't ignore the urge to pee. And lean forward to empty your bladder completely when you urinate.
• After a bowel movement, wipe yourself from front to back to prevent bacteria in the stool from getting near the urethra.
• Keep your genital area clean with mild soap and water.
• Clean your genital area and pee before and after sexual intercourse .
• Drink unsweetened cranberry juice. Studies show that cranberry juice – or taking cranberry pills – may reduce bacteria levels and discourage new bacteria from taking hold in the urinary tract. (Drinking cranberry juice won't cure an existing infection, though, so if you're having symptoms, you still need to see your practitioner right away to get a prescription for antibiotics.)
• Don't use feminine hygiene products (sprays or powders) and strong soaps that can irritate your urethra and genitals , making them a better breeding ground for bacteria. And don't use douches during pregnancy.

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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 .

ACOG. 2020. Urinary tract infections. American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/urinary-tract-infections Opens a new window [Accessed August 2021]

ACOG. 2017. Guidelines for perinatal care, eighth edition. American College of Obstetricians and Gynecologists. https://reader.aappublications.org/guidelines-for-perinatal-care-8th-edition/2 Opens a new window [Accessed August 2021]

Ailes EC, et al. 2018. Antibiotics Dispensed to Privately Insured Pregnant Women with Urinary Tract Infections — United States, 2014. MMWR Morbidity and Mortality Weekly Report.  67:18–22. https://www.cdc.gov/mmwr/volumes/67/wr/mm6701a4.htm Opens a new window [Accessed August 2021]

Bergamin PA, et al. 2017. Non-surgical management of recurrent urinary tract infections in women.  Translational Andrology and Urology;  6(Suppl 2): S142-S152. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522788/ Opens a new window [Accessed August 2021]

Habak PJ and Griggs RP. 2019. Urinary tract infection in pregnancy. National Center for Biotechnology Information. https://www.ncbi.nlm.nih.gov/books/NBK537047/ Opens a new window [Accessed August 2021]

IOM. 2005. Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Food and Nutrition Board, Institute of Medicine, National Academies. https://www.nap.edu/read/10925/chapter/6#152 Opens a new window [Accessed August 2021]

Matuszkiewicz-Rowinska, J., et al. 2015. Urinary tract infections in pregnancy: Old and new unresolved diagnostic and therapeutic problems. Archives of Medical Science 11(1):66-7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4379362/ Opens a new window [Accessed August 2021]

Nicolle LE, et al. 2019. Clinical practice guideline for the management of asymptomatic bacteriuria: 2019 update by the Infectious Diseases Society of America. Clinical Infectious Diseases 68(10):83-110. https://academic.oup.com/cid/article/68/10/e83/5407612 Opens a new window [Accessed August 2021]

Moore A, et al. 2018. Recommendations on screening for asymptomatic bacteriuria in pregnancy . CMAJ 190:E823-30. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6041243/pdf/190e823.pdf Opens a new window [Accessed August 2021]

Smaill FM, et al. 2019. Antibiotics for asymptomatic bacteriuria in pregnancy. Cochrane Database of Systematic Reviews. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000490.pub4/full Opens a new window [Accessed August 2021]

UpToDate. 2020. Urinary tract infections and asymptomatic bacteriuria in pregnancy. https://www.uptodate.com/contents/urinary-tract-infections-and-asymptomatic-bacteriuria-in-pregnancy Opens a new window [Accessed August 2021]

U.S. Preventive Services Task Force. 2019. Screening for asymptomatic bacteriuria in Adults: U.S. Preventive Services Task Force recommendation statement. JAMA 322(12):1188-94. https://jamanetwork.com/journals/jama/fullarticle/2751726 Opens a new window [Accessed August 2021]

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Urinary Tract Infections During Pregnancy: Symptoms, Treatment, and Common Questions

Physical and hormonal changes that happen during pregnancy increase a woman’s chance of developing a UTI.

Urinary tract infections (UTIs), also known as bladder infections, are a very common type of bacterial infection .

One study suggested as many as 1 in 3 women will have a bladder infection at some point in their pregnancy. UTIs occur when bacteria enter into the usually sterile urinary tract and multiplies, causing painful urination and other symptoms. Certain factors during pregnancy make this occurrence more likely to happen. Here’s what you need to know to keep you and your baby healthy.

RELATED: 7 Home Remedies for Urinary Tract Infection (UTI) Symptoms

Why Are UTIs Common in Pregnant Women?

When you’re pregnant, the anatomy of your urinary tract actually changes. For instance, your kidneys become larger, and your growing uterus can compress your ureters and bladder. Because of this compression, fully emptying your bladder during pregnancy becomes more difficult. In addition, your progesterone and estrogen levels increase during pregnancy, which can weaken your bladder and ureters, per research .

Pregnancy also alters the makeup of your urine, according to the Children’s Hospital of Philadelphia , reducing the acidity and increasing the amount of protein, hormones, and sugar in your urine. Research has found that excess sugar can encourage bacterial growth. All of the above contribute to a heightened chance of developing a UTI in pregnancy. And that is why it’s recommended that all pregnant women receive a urinalysis and urine culture at 12 to 16 weeks, or during the first prenatal visit.

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UTIs by Pregnancy Trimester

Your risk of UTI goes up beginning at week 6 of your pregnancy; the chances you’ll have a UTI vary by trimester.

First Trimester

According to the Centers for Disease Control and Prevention (CDC) , about 41 percent of UTIs are diagnosed during the first trimester . Because getting a UTI during the first trimester is so common, the U.S. Preventive Services Task Force recommends that your healthcare provider obtain a urinalysis and urine culture at your first prenatal visit. That recommendation holds whether you present with UTI symptoms or not.

Second Trimester

About half as many pregnant women are diagnosed with a UTI during their second trimester compared with the first trimester, according to the CDC.

Third Trimester

Compared with the second trimester, the number of women who experience a UTI during the third trimester is almost halved. However, 80 to 90 percent of acute kidney infections in pregnancy (many caused by the progression of an untreated UTI) occur in the second and third trimesters, according to research . Thus, it’s recommended to do a repeat urine culture during the third trimester, too.

Common UTI Symptoms in Pregnant Women

“While mildly painful urination during pregnancy can often mean a yeast infection, not a UTI, it’s always best to see your healthcare provider if you experience any symptoms,” says Heather Bartos, MD , a gynecologist in Cross Roads, Texas. Among the telltale UTI signs and symptoms are:

• Strong and frequent urge to use the bathroom
• Burning while urinating
• Regularly passing only small amounts of urine
• Cloudy, red, pink, or cola-colored urine
• Pelvic pain, usually in the center of the pelvis

In pregnancy, women are also more susceptible to asymptomatic bacteriuria, meaning you have significant bacteria in your urine, but your urinary tract is free of signs and symptoms. Experiencing no symptoms, however, does not mean that asymptomatic UTIs are benign.

“An asymptomatic UTI can lead to a symptomatic UTI or even a kidney infection [in pregnant women],” says Dr. Bartos. In fact, research has shown that if asymptomatic UTIs in pregnancy are left untreated, 30 percent of pregnant women will go on to develop a symptomatic UTI, and half of those women will eventually be diagnosed with acute pyelonephritis (a kidney infection). Up to 23 percent will have a kidney infection recurrence during the same pregnancy. It’s important to note that classic UTI signs, like frequent and painful urination, may or may not occur with a kidney infection. Here are some signs to look out for:

Typical Signs of a Symptomatic UTI

• High-grade fever
• Chills and rigors (sudden feeling of cold with shivering)
• Nausea or vomiting
• Lower back pain
• Flank pain (often right side)
• Possible reduced urine output

Are UTIs Dangerous During Pregnancy?

“UTIs can rapidly progress to kidney infections in pregnancy, which can be much more dangerous than a kidney infection in nonpregnant women,” says Bartos. “Severe infections can lead to respiratory problems and sepsis , which can then lead to preterm labor or even the need to urgently deliver the baby.”

Beyond a kidney infection, simply having a UTI during pregnancy appears to possibly be a contributing factor to low birth weight. According to a meta-analysis , women who have a UTI in pregnancy also have a 1.3 times higher risk of developing preeclampsia, a pregnancy complication characterized by high blood pressure . It’s thought that a UTI may alter a pregnant woman’s inflammatory response, which can spur preeclampsia .

Can Having a UTI While Pregnant Hurt the Baby?

Possibly. “A UTI itself doesn’t hurt the baby directly,” says Bartos. “It’s the failure to treat a UTI that can cause things like preterm birth or, rarely, infection of the amniotic sac.” For example, research has shown that treating pregnant women who have asymptomatic UTIs decreases the incidence of preterm birth and low-birth-weight infants. That’s why screening and prompt treatment are important.

Can a UTI Cause Contractions During Pregnancy?

If a urinary tract infection is left untreated, it can progress to a kidney infection. And a kidney infection (pyelonephritis) during pregnancy can modestly increase your chances of early contractions and delivery. Research   notes that women diagnosed with acute pyelonephritis in pregnancy have a 10.3 percent chance of preterm delivery compared with the 7.9 percent chance among women without a kidney infection during pregnancy.

RELATED : Common Types of Vaginal Infections

Do UTIs Differ by Trimester?

At week 6, UTI risk starts to go up, with two-fifths of UTIs occurring during the first trimester .  Because of the likelihood of getting a UTI during the first trimester, as noted above, the U.S. Preventive Services Task Force recommends that pregnant women have a urinalysis and urine culture at their first prenatal visit — whether they have UTI symptoms or not. In the second trimester, about half as many pregnant women are diagnosed with a UTI as in the first trimester, according to the CDC , and that number is almost halved again for the third trimester. However, 80 to 90 percent of acute kidney infections in pregnancy (many caused by the progression of an untreated UTI) occur in the second and third trimesters, per research , so pregnant women should have a repeat urine culture during the third trimester.

RELATED : March Is Endometriosis Awareness Month

What Are Pregnancy-Safe UTI Treatment Options?

How do you treat a UTI when pregnant? It’s similar to how you treat a UTI when not pregnant — with a few key differences. A short course of antibiotics is the standard treatment for asymptomatic and symptomatic urinary tract infections that occur during pregnancy. There are, however, two important contrasts in treating UTIs in pregnant women versus nonpregnant women. First, asymptomatic UTIs diagnosed during the first trimester are treated with antibiotics, according to the National Institute for Health and Care Excellence , whereas nonpregnant women’s infections are often not treated in this manner, per UpToDate . (Outside of pregnancy, asymptomatic bacteriuria is usually not treated with antibiotics.) Also, the preferred antibiotic drugs used to treat UTI in pregnancy often differ than what would be used while not pregnant. For instance, the following antibiotics have not been associated with any birth defects, thus are likely safe to use at any point during pregnancy:

• Penicillins , including   amoxicillin (Amoxil) ,  ampicillin (Omnipen) , and amoxicillin and clavulanate potassium (Augmentin)
• Erythromycin (MY-E)
• Cephalosporins , including cephalexin (Keflex)

UTI history and resistance patterns must be considered before prescribing any of these drugs.

Because certain antibiotics are associated with a potential risk for birth defects (anencephaly, heart defects, and cleft palate) when taken during the first trimester, in most cases they are only considered a first-line treatment for UTIs occurring during the second and third trimesters.

Nitrofurantoin (Macrobid) may be used during the first trimester, but in general, medical treatment is avoided, though a bladder infection would be treated with antibiotics. Sulfamethoxazole and trimethoprim oral/injection (Bactrim) is considered appropriate during the first trimester only when no other suitable alternative treatment is available.

Be sure to double-check what your healthcare provider is prescribing.

Editorial Sources and Fact-Checking

Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy . We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

• Amiri M, Lavasani Z, Norouzirad R, et al. Prevalence of Urinary Tract Infection Among Pregnant Women and Its Complications in Their Newborns During the Birth in the Hospitals of Dezful City, Iran, 2012–2013. Iranian Red Crescent Medical Journal . August 2015.
• Loh KY, Sivalingam N. Urinary Tract Infections in Pregnancy. Malaysian Family Physician . 2007.
• Urinary Tract and Kidney Infections During Pregnancy. Children’s Hospital of Philadelphia .
• Imade PE, Izekor PE, Eghafona NO, et al. Asymptomatic Bacteriuria Among Pregnant Women. North American Journal of Medical Sciences . June 2010.
• U.S. Preventive Services Task Force. Screening for Asymptomatic Bacteriuria in Adults: U.S. Preventive Services Task Force Recommendation Statement. JAMA . September 24, 2019.
• Ailes EC, Summers AD, Tran EL, et al. Antibiotics Dispensed to Privately Insured Pregnant Women With Urinary Tract Infections — United States, 2014 [PDF]. Centers for Disease Control and Prevention . January 12, 2018.
• Matuszkiewicz-Rowinska, J, Malyszko J, Wieliczko M. Urinary Tract Infections in Pregnancy: Old and New Unresolved Diagnostic and Therapeutic Problems. Archives of Medical Science . March 16, 2015.
• Delzell Jr. JE, Lefevre ML. Urinary Tract Infections During Pregnancy. American Family Physician . February 1, 2000.
• Yan L, Jin Y, Hang H, Yan B. The Association Between Urinary Tract Infection During Pregnancy and Preeclampsia: A Meta-Analysis. Medicine . September 2018.
• Wing DA, Fassett MJ, Getahun D. Acute Pyelonephritis in Pregnancy: An 18-Year Retrospective Analysis. American Journal of Obstetrics & Gynecology . March 2014.
• Antenatal Care. National Institute for Health and Care Excellence . August 19, 2021.
• Fekete T. Asymptomatic Bacteriuria in Adults. UpToDate . May 31, 2023.

What to Do If You Get a UTI During Pregnancy

Medical review policy, latest update:.

Medically reviewed for accuracy.

What is a UTI?

How common are utis during pregnancy, more on pregnancy health, uti symptoms during pregnancy, what causes a uti during pregnancy, uti diagnosis and treatment, preventing utis during pregnancy, updates history, jump to your week of pregnancy, trending on what to expect, signs of labor, pregnancy calculator, ⚠️ you can't see this cool content because you have ad block enabled., top 1,000 baby girl names in the u.s., top 1,000 baby boy names in the u.s., braxton hicks contractions and false labor.

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Is it an emergency? Dial 000 If you need urgent medical help, call triple zero immediately.

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Urinary tract infections (UTIs) during pregnancy

9-minute read

• Urinary tract infections (UTIs) are the most common bacterial infection in pregnancy, and if you’re pregnant you have a 1 in 10 change of having one.
• Symptoms of UTIs include stinging or pain when you pass urine (wee), a need to pass urine more often, leaking urine, or a fever.
• If you have bacteria in the urine or a UTI during pregnancy, your doctor will prescribe an antibiotic to treat it.
• If you have a UTI in pregnancy, your doctor will work with you to try to prevent it becoming a kidney infection.

What is a urinary tract infection?

A urinary tract infection (UTI) is an infection of the urinary system . It can occur in different parts of the urinary tract, including the bladder ( cystitis ) and kidneys ( pyelonephritis ). The bacteria usually come from the gut ( digestive system ) where they don’t cause problems, and move to the urinary tract.

Sometimes bacteria is found in the urinary tract, but you don’t have any symptoms of an infection. This is known as asymptomatic bacteriuria. Your doctor or midwife will test for this in your first trimester of pregnancy by asking you to provide a urine sample . If you have bacteria in your urine, even if you don’t have symptoms, your doctor will prescribe treatment, to prevent problems for you or your baby.

UTIs can affect you whether you are pregnant or not. If you’re pregnant, you have up to a 1 in 10 chance of having a UTI. It is the most common infection in pregnancy. If you have a UTI while you’re pregnant, you are also more likely to develop other, more harmful, infections.

What are the symptoms of UTIs during pregnancy?

Common symptoms of a UTI during pregnancy are similar to those that you might experience at any other time , and include:

• pain or a burning sensation when you pass urine
• feeling the urge to urinate more often than usual
• urinating before you reach the toilet (‘leaking’ or incontinence )
• feeling like your bladder is full, even after you have urinated
• urine that looks cloudy, bloody or is very smelly
• pain in the lower abdomen or above the pubic bone

If the infection has moved to the kidneys, you may also have a high fever, back pain and vomiting .

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What are the common causes of UTIs?

Your urinary tract is normally free of bacteria. If bacteria enter the tract and multiply, they can cause a UTI. Some reasons that increase your risk of developing an infection include:

• being sexually active more than 3 time a week, which increases the risk of bacteria moving around the genital area and entering the urinary tract
• having problems emptying your bladder completely
• having diabetes , as the sugar in your urine may cause bacteria to multiply

During pregnancy, changes that occur in your body will increase your risk of getting a UTI, including changes to your urine and immune system . As your baby grows, there is also increased pressure on your bladder, which can reduce the flow of your urine and lead to an infection. The tubes that take urine from the kidney to the bladder (ureters) get wider, which makes it easier for bacteria to get to the kidneys.

What are the complications of UTIs during pregnancy?

A bladder infection is more likely to become a kidney infection if you are pregnant than if you are not pregnant. In pregnancy, kidney infections are more severe and may cause problems for both you and your baby.

Having bacteria in your urine (even if you don’t have pain or other symptoms) is associated with a condition called pre-eclampsia . Pre-eclampsia is a serious medical condition in pregnancy that causes high blood pressure and can affect many body organs, including the liver, kidney and brain. If left untreated, it can lead to serious problems for you or your baby, but early treatment prevents these problems.

A kidney infection can cause problems such as severe infection ( sepsis ), blood pressure problems and kidney damage.

Is there a risk to my baby?

If you have bacteria in your urine, or a kidney infection while you’re pregnant, your baby is at a higher risk of an early birth or being born underweight. This risk doesn’t occur with a bladder infection, so long as it is treated.

The best way to avoid a risk to your baby is to keep all your antenatal appointments with your doctor, midwife or clinic.

How are UTIs diagnosed?

UTIs are diagnosed by taking a urine sample , which is checked in a laboratory under the microscope for bacteria. Your doctor will also ask you about your symptoms and may do a physical examination .

Everyone who is pregnant will be offered a urine test, usually at their first antenatal visit or soo n after. You may need to repeat the urine test if you have had UTIs in the past, have symptoms of a UTI, have a sample with an unclear result, or if your doctor thinks you are at high risk of developing a UTI. If you have many UTIs, you may need more tests such as an ultrasound of your kidneys.

How are UTIs treated during pregnancy?

UTIs are treated with antibiotics that are safe in pregnancy . Your doctor will prescribe the right antibiotic , based on your infection and the type of bacteria found in your urine sample. If your doctor is concerned about your UTI, they may start you on one antibiotic straight away, and then change the antibiotic if the bacteria is best treated with a different antibiotic.

If you have had many infections or many samples showing bacteria in your urine, your doctor may prescribe regular antibiotics in your pregnancy to prevent more infections from developing (prophylaxis).

It is also recommended to have a repeat urine test a few weeks after you finish your antibiotic treatment to ensure that the infection has cleared.

Can I prevent UTIs?

You can lower your risk of developing a UTI during pregnancy by:

• drinking plenty of fluids , especially water
• going to pass urine (wee) when you get the urge, and not delaying
• urinating immediately after sex
• wiping from the front to the back after going to the toilet
• showering instead of having a bath
• avoiding douching and sprays or powders in the genital area

When should I see my doctor?

See your midwife or GP if you have any symptoms of a UTI. It’s important not to delay getting antibiotics, as infections develop quickly, and can lead to problems for you and your baby.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

Resources and support

For more information on UTIs, visit the Kidney Health Australia page on UTIs .

Mothersafe has information sheets about urinary tract infection in pregnancy .

Read the Queensland Government’s guide to UTIs for Aboriginal and/or Torres Strait Islander people.

Learn more here about the development and quality assurance of healthdirect content .

Last reviewed: August 2023

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• Frequent urination during pregnancy
• Bladder and bowel incontinence during pregnancy
• Sepsis during pregnancy and after childbirth

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• Volume 12, Issue 9
• Diagnostic work-up of urinary tract infections in pregnancy: study protocol of a prospective cohort study
• Article Text
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• http://orcid.org/0000-0003-3121-0441 Dominique Esmée Werter 1 ,
• Brenda M Kazemier 1 ,
• Elisabeth van Leeuwen 2 ,
• Maurits C F J de Rotte 3 ,
• Sacha D Kuil 4 ,
• Eva Pajkrt 5 ,
• Caroline Schneeberger 6 , 7
• 1 Department of Obstetrics and Gynaecology , University of Amsterdam , Amsterdam , The Netherlands
• 2 Department of Obstetrics and Gynaecology , Amsterdam University Medical Centres , Duivendrecht , The Netherlands
• 3 Department of Clinical Chemistry , University of Amsterdam , Amsterdam , The Netherlands
• 4 Department of Microbiology , University of Amsterdam , Amsterdam , The Netherlands
• 5 Obstetrics and Gynaecology , Amsterdam UMC Location AMC , Amsterdam , The Netherlands
• 6 Department of Microbiology , Amsterdam UMC-Locatie AMC , Amsterdam , The Netherlands
• 7 Center for Infectious Disease Control , National Institute for Public Health and the Environment (RIVM) , Bilthoven , Netherlands
• Correspondence to Ms Dominique Esmée Werter; d.e.werter{at}amsterdamumc.nl

Introduction Symptoms of urinary tract infections in pregnant women are often less specific, in contrast to non-pregnant women where typical clinical symptoms of a urinary tract infection are sufficient to diagnose urinary tract infections. Moreover, symptoms of a urinary tract infection can mimic pregnancy-related symptoms, or symptoms of a threatened preterm birth, such as contractions. In order to diagnose or rule out a urinary tract infection, additional diagnostic testing is required.

The diagnostic accuracy of urine dipstick analysis and urine sediment in the diagnosis of urinary tract infections in pregnant women has not been ascertained nor validated.

Methods and analysis In this single-centre prospective cohort study, pregnant women (≥16 years old) with a suspected urinary tract infection will be included. The women will be asked to complete a short questionnaire regarding complaints, risk factors for urinary tract infections and baseline characteristics. Their urine will be tested with a urine dipstick, urine sediment and urine culture. The different sensitivities and specificities per test will be assessed. Our aim is to evaluate and compare the diagnostic accuracy of urine dipstick analysis and urine sediment in comparison with urine culture (reference test) in pregnant women. In addition, we will compare these tests to a predefined ‘true urinary tract infection’, to distinguish between a urinary tract infection and asymptomatic bacteriuria.

Ethics and dissemination Approval was requested from the Medical Ethics Review Committee of the Academic Medical Centre; an official approval of this study by the committee was not required. The outcomes of this study will be published in a peer-reviewed journal.

• Urinary tract infections
• BACTERIOLOGY
• Protocols & guidelines
• Microbiology
• Maternal medicine

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:  http://creativecommons.org/licenses/by-nc/4.0/ .

https://doi.org/10.1136/bmjopen-2022-063813

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STRENGTHS AND LIMITATIONS OF THIS STUDY

The urine of every participating woman will be tested with a set of tests including a urine dipstick, urine sediment and a urine culture.

We will investigate the course of complaints in pregnant women with a possible urinary tract infection to gain more insight in the diagnostic value.

The research will be done prospectively; therefore, we expect less bias than in a retrospective cohort.

It will be a single-centre cohort study, so it could possibly make the participants more homogeneous.

Introduction

The prevalence of urinary tract infections (UTIs) during pregnancy reported in literature varies between 2.3% and 15%. 1–5 It is hypothesised that anatomical changes during pregnancy such as dilatation of the ureters, decreased ureteral tone and increased bladder volume contribute to urinary stasis and ureterovesical reflux increasing the risk of a UTI. 6–8 Besides the anatomical changes, pregnancy-related glomerular filtration rate increases the alkalinity of the urine and the urinary glucose concentration, which facilitates bacterial growth. 9 The association between UTIs during pregnancy and maternal complications such as hypertensive disorders and caesarean delivery has been reported, although there is contradictory evidence. 4 6 10 Moreover, UTIs during pregnancy have also been associated with neonatal complications such as preterm birth, low birth weight and perinatal death. 2 4 10 In addition, an untreated UTI may lead to pyelonephritis, which further increases the risk of preterm birth. 11 Preterm birth has major consequences at the individual level as well as for society (costs).

In contrast, overtreating pregnant women with antibiotics may also cause harm. Overuse and incorrect use of antibiotics are the main causes of antimicrobial resistance. Moreover, the unnecessary exposure of the unborn child to antibiotics may also not be without risks. Associations between antibiotics during pregnancy and adverse neonatal outcomes including increased risk of cerebral palsy, early-onset sepsis with antibiotic-resistant microorganisms, malformations and epilepsy have been published. 10 12 13 Also, maternal exposure to certain antibiotics is associated with childhood asthma and childhood obesity. 14 15 It is recently found that prenatal exposure to antibiotics can probably lead to alterations in the differential methylation at regulatory regions of imprinted genes. 16 If we can improve diagnostics and related antibiotic prescribing, we possibly can also influence fetal development and possibly long-term health with the results of this study. All of them impact future healthcare costs. Next to that, if we could decrease the number of tests for an accurate diagnosis, costs could be saved.

In the non-pregnant population, a diagnostic test to confirm the diagnosis of UTI is not always considered necessary, since typical clinical symptoms such as dysuria and urgency are regarded distinctive enough. 7 17–20 In pregnancy, the diagnosis of a UTI is less well studied and more challenging. First of all, many women during pregnancy experience symptoms that mimic a UTI such as frequency as a result of pressure of the baby’s head on the bladder. 8 21 On the other hand, symptoms of a UTI can be aspecific in pregnancy; UTIs in pregnant women may solely present with abdominal pain or Braxton Hicks contractions. 9 21 All this makes it more difficult to distinguish between asymptomatic bacteriuria (ASB) and UTI. Furthermore, in pregnancy, ASB can also be present: bacteriuria without any UTI signs or symptoms. ASB is not an active infection and the risk of adverse outcomes like preterm birth is low or absent compared with UTIs. 11 22

Most hospital protocols recommend testing pregnant women for a UTI when they present with symptoms suggestive of UTI or in case of symptoms suspicious of threatened preterm birth. In the diagnostic work-up, various methods are used: urine dipstick test, urine sediments and bacterial cultures, which are used in various ways and come with several limitations.

First, a urine dipstick is a strip with different reagents present. The reagents react on the presence of certain substances, for example, protein, glucose, nitrite and leucocyte esterase. The most important parameters to diagnose UTI on a dipstick are nitrite and leucocyte esterase. Many gram-negative bacteria produce the enzyme nitrate reductase, which converts urinary nitrate into nitrite indicating the presence of bacteria. 23 In the adult population, the sensitivity of nitrite dipstick reported in a systematic review is 0.54 (CI 0.44 to 0.64), the specificity is 0.98 (CI 0.96 to 0.99), positive likelihood ratio of 29.3 (CI 14.4 to 59.7) and a negative likelihood ratio of 0.48 (CI 0.37 to 0.62). Eight out of 14 of the studies included in this review reported on pregnant women, but none of them reported on symptomatic women. 24 Another study shows that the sensitivity and specificity of nitrite to test for ASB in pregnant women are, respectively, 0.55 (95% CI 0.42 to 0.67) and 0.99 (95% CI 0.98 to 0.99). 25

Leucocyte esterase is an enzyme released by neutrophils and macrophages. The leucocyte dipstick has a sensitivity of 0.72 (0.61 to 0.84) and a specificity of 0.82 (0.74 to 0.90), and a positive likelihood ratio of 4.87 (3.26 to 7.29) and a negative likelihood ratio of 0.31 (0.18 to 0.51) in the adult population. 24

Physiological pyuria can appear in pregnant women. 26

Second, for urine sediments, urine samples are centrifuged to obtain a sediment including red and white blood cells, squamous cells and bacteria, which are counted automatically by microscopy. 16 For a UTI, both the presence or absence of leucocytes and bacteria are of interest. A systematic review in the general population reported a sensitivity range of 57.1%–97%, a specificity of 27.0%–97.0%, a positive likelihood ratio of 1.59–24.57 and a negative likelihood ratio of 0.07–0.655 in studies where they used the sediment. 27 Yet again, physiological pyuria can appear in pregnant women. 26 The advantage of the urine sediment over the urine dipstick is that the urine sediment counts all bacteria. The urine dipstick only indicates if there are nitrite-forming bacteria present. However, not all bacteria are uropathogenic.

Finally, the reference test to detect a UTI is a urine culture, which determines bacterial growth. However, the urine dipstick takes a few minutes, the urine sediment about an hour and the urine culture at least 24 hours up to 5 days.

The exact number of bacteria present in urine to define a ‘positive’ urine culture and a UTI is not clear cut. The most common definition is ≥10 5 colony-forming units (CFU)/mL of uropathogens. 28 However, the cut-offs used in practice range from ≥10 3  CFU/mL to ≥10 5  CFU/mL. 18 29 30

The Dutch guideline of obstetrics and gynaecology recommends performing both a nitrite dipstick and a urine culture when pregnant women present with UTI symptoms. In case of a positive nitrite dipstick, treatment should start immediately. In case of a negative nitrite dipstick, treatment should only be started if the culture is positive. The role of the other diagnostic methods is unclear. 9 The Dutch general practitioners’ guideline recommends performing a nitrite dipstick. In case of a positive nitrite dipstick, people will be treated for UTI. Leucocyte esterase test will be performed when the nitrite result is negative. Urine sediments are recommended if leucocyte esterase is present since a positive result of leucocyte esterase is considered as insufficient proof of a UTI. When either the nitrite or the sediment is positive, treatment should be started. When the leucocyte esterase dipstick is negative but there is still a suspicion for a UTI, a sediment is performed additionally. When both urine dipstick and sediment are negative, a UTI is ruled out. If either urine dipstick or sediment results are positive, a urine culture is performed while antibiotics are directly initiated, awaiting the urine culture results. 31

Both in the UK and the USA, guidelines do not state the diagnostic work-up for UTIs in pregnancy (Royal College Obstetricians and Gynaecologist (RCOG) guideline, National Institue for Health and Care Excellence (NICE)guideline and American College of Obstetricians and Gynecologist (ACOG) guideline).

Despite the differences in guidelines, in daily practice, the urine is often only tested with a dipstick. In case of a negative test result, often no additional tests are done. The approach when to perform a sediment or a urine culture is equally ambiguous. There is no clear evidence that the diagnostic accuracy of a standalone dipstick urine (including both the presence of nitrite and leucocyte esterase) is equal to a combined approach of urine dipstick and sediment to diagnose a UTI in pregnancy. Furthermore, pyuria can be present in pregnant women without a UTI. 26 Moreover, the additional value of a urine culture in all women, as recommended by the Dutch guideline of obstetrics and gynaecology, is also unknown. For something as common as a UTI during pregnancy, it is undesirable that the available evidence is too limited to properly inform (diagnostic) guidelines, which results in great diagnostic variation, and potential harmful overtreatment and undertreatment.

Methods and analysis

This study aims to evaluate the diagnostic accuracy of urine dipstick analysis and urine sediment to bacterial cultures in the diagnosis of UTI in pregnant women.

Study design

This study is a single-centre prospective cohort study.

Participants

All consecutive pregnant women attending the outpatient clinic, the pregnancy ward or emergency department for women’s health in the Amsterdam UMC with symptoms warranting a diagnostic work-up to rule out a UTI can be included, after oral and written consent. These symptoms include dysuria, urgency, frequency, fluid loss, difficulties with voiding, painful voiding, haematuria, or aspecific abdominal pain, (Braxton Hicks) contractions and vaginal blood loss. 7 9

Exclusion criteria are a previous UTI episode in the past 2 weeks, antibiotic use in the past 2 weeks or a structural abnormality of the urogenital tract.

Inclusion of women in the study takes place since 1 November 2021. We plan to include all women in the study in 3 years.

Test methods

The urine samples will be clean-catch midstream urine samples. The index test will be a urine dipstick and a urine sediment. The dipstick that we will use is Clinitek novus 10 (Siemens). The urine sediment will be checked with Atellica 1500 Siemens. For both the urine dipstick and the urine sediment, different cut-offs will be used to investigate which cut-off has the best diagnostic value ( table 1 ).

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Expected outcomes

The reference test will be a urine culture.

No blinding will take place for the different tests. The outcome of the test has no influence on the treatment and is necessary for daily practice.

Because of the difficulties to distinguish between ASB and UTI, we will use a different definition for UTI than commonly used. We would like to make sure that we are dealing with a UTI and not ASB.

In this study, a ‘true UTI’ is present when the following three criteria are met:

Presence of at least two specific or non-specific symptoms of a UTI. 26

A positive urine culture.

Symptom improvement during adequate antibiotic treatment, where adequate treatment is defined by proven susceptibility of isolated uropathogens to the administered antibiotic.

The definition of a positive culture is:

Urine with ≥10 3  CFU/mL of a uropathogen.

Maximum of two uropathogens ≥10 3  CFU/mL present. When there are more than two uropathogens present of ≥10 3  CFU/mL, the culture will be considered as contaminated.

Next to that, the woman will be asked to fill out a questionnaire. The questionnaire contains questions about risk factors for UTI and possible clinical symptoms of a UTI. After 5–8 days, when the result of the culture will be available, the woman will be called to evaluate the presenting symptoms. This check-up is part of standard care. Both the woman and the clinician have access to the test result; it is not blinded. Women will be asked permission to collect data from the midwife, gynaecologist or general practitioner about their pregnancy and delivery.

The statistical analysis will be performed using IBM SPSS Statistics V.26.

Primary outcome

We will determine which combination of leucocyte esterase, nitrite presence in the dipstick and bacteria presence and leucocyte count in the sediment yield the best performance of both methods separately and combined to predict a ‘true UTI’ according to our definition. Different cut-offs and combinations of cut-offs of the urine analysis components will be explored to calculate sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios ( table 1 ). In addition, we aim to develop a diagnostic model based on all available evidence on leucocyte esterase, nitrite presence, bacteria presence, leucocyte count and symptoms.

After the best performing cut-offs for both urine dipstick and urine sediment have been determined, we will compare the performance of these two tests together in terms of sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios. Urine culture will be used as the reference test. The performance will be compared with the predefined ‘true’ UTI. To do this, we first select all true positives and true negatives using the reference test. In addition, we compare the classifications of urine dipstick with urine sediment in a 2×2 table for true positives (sensitivity) and a 2×2 table for true negatives (specificity) and calculate a p value for the difference in classification using a paired McNemar test.

Planned sensitivity analyses will also be performed for different cut-off values for pathogens in urine cultures ≥10 3  CFU/mL, ≥ 10 4  CFU/mL and ≥10 5  CFU/mL.

Contaminated urine cultures will be considered as negative cultures.

Secondary outcome

We will evaluate which clinical symptoms are best at predicting a UTI in pregnancy and which symptoms are not. The symptoms of a UTI will be studied with incidences and p values to identify which symptoms are associated with UTI.

To identify risk factors for UTI, univariate logistic regression will be used. In case it is possible, multivariate logistic regression will be used to identify the risk factors. We will use a forward stepwise selection for our regression model.

Pregnancy duration will be measured in weeks and days of gestational age and will be compared between women with and without UTI with a Student’s t-test.

The timing of the performed urine test (urine dipstick, urine sediment and urine culture) and the gestational age of delivery will be noted. Time between diagnosis of UTI and delivery will be compared using Kaplan-Meier survival curve.

Power analysis

To provide an estimated sample size, we calculated the sample sizes necessary for 80% power in a McNemar paired test comparing urine dipstick with urine sediment in women with true-positive UTI (sensitivity) and true-negative UTI (specificity). The expected discrepant cells for sensitivity are 14% and 5%, with a calculated 181 true-positive cases necessary for 80% power. The expected discrepant cells for specificity are 10% and 4% with a calculated 302 true-negative cases necessary for 80% power. We expect that around 30% of the included women will have a UTI such that the necessary sample size to include is 603 for sensitivity and 432 for specificity.

With a 10% expected drop-out, the sample size would be 660 pregnant women.

Data will be collected using Castor, which is an application system that enables collection and clean-up of trial data using the internet. Data handling will be done coded. The data will be saved for 15 years.

Patient and public involvement

There was no patient or public involvement in this research.

Ethics and dissemination

Approval was requested from the Medical Ethics Review Committee of the Academic Medical Centre; an official approval of this study by the committee was not required (METC review number W21_291 #21.318). All participants will give written and oral informed consent prior to entry to the study and will be made aware that participation is strictly voluntary.

The outcomes of this study will be published in a peer-reviewed journal.

The diagnostic accuracy of a urine dipstick and, less often, a urine sediment for the diagnosis of bacteriuria in pregnancy has been evaluated. 23 32 However, no studies are available in pregnant women on the diagnostic accuracy of symptomatic UTIs. As a result, different guidelines in the Netherlands advise different ways of testing for UTIs in pregnant women. International guidelines lack any recommendations on specific urine tests. However, in pregnant women with a UTI, both undertreatment and overtreatment are potentially harmful; therefore, correct diagnosis is very important.

The focus of this study is the diagnostic work-up. We will not intervene in the treatment given or follow-up provided to the participating women. It is likely that certain types of bias will be introduced as a result of implementation of this study. Bias could be introduced because more diagnostics will be performed and all three urine test results will be reported to the treating clinician (not blinded). Since more result will be available, this could affect the prescription of antibiotics.

We do not expect a lot of women with partial verification bias since the three different urine tests will be most of the time executed at the same time from the same urine sample. Because of this, we avoid that only the urine dipstick and/or sediment is performed and the urine culture is not executed.

The urine culture has been used, both in daily practice and in research, for a long time. There are no logical alternative reference standards. The urine culture has been proven to be effective. We do not expect an inappropriate reference standard.

Since the result of the urine culture is only available a few days after the results of the urine dipstick and sediment, we do not expect a review bias.

Clinical impact

Due to the different cut-offs to report uropathogens and their susceptibilities (10 3 instead of 10 4 ), the rate of prescribing antibiotics may increase too. However, the result of the culture will only come in after a few days, so the decision to start antibiotics has most likely already been made. With this study, we hope to provide either better evidence for the current advice in guidelines and/or guide necessary adjustments.

To avoid unnecessary treatments, diagnostic tests and costs, and to minimise possible harmful neonatal outcomes, the diagnostic process of UTIs should be optimised. This new workflow should be implemented in the daily care to create a more evidence-based treatment strategy. Since the diagnostic work-up for UTIs takes place on a daily basis, the results of this research will have a major impact on daily routine care. To find an optimal strategy for diagnosing a UTI is only the start of tackling the challenges around the diagnosis of UTIs in pregnancy.

Ethics statements

Patient consent for publication.

Not required.

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• Devillé WLJM ,
• Yzermans JC ,
• van Duijn NP , et al

Contributors DEW wrote the proposal and the manuscript. BMK initiated the research, and critically revised the proposal and manuscript. EvL critically revised the proposal and manuscript. MCFJdR critically revised the manuscript. SDK critically revised the proposal and manuscript. EP critically revised the proposal and manuscript. CS critically revised the proposal and manuscript. All authors read and approved the final manuscript.

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Provenance and peer review Not commissioned; externally peer reviewed.

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• v.12(9); 2022

Diagnostic work-up of urinary tract infections in pregnancy: study protocol of a prospective cohort study

Dominique esmée werter.

1 Department of Obstetrics and Gynaecology, University of Amsterdam, Amsterdam, The Netherlands

Brenda M Kazemier

Elisabeth van leeuwen.

2 Department of Obstetrics and Gynaecology, Amsterdam University Medical Centres, Duivendrecht, The Netherlands

Maurits C F J de Rotte

3 Department of Clinical Chemistry, University of Amsterdam, Amsterdam, The Netherlands

Sacha D Kuil

4 Department of Microbiology, University of Amsterdam, Amsterdam, The Netherlands

5 Obstetrics and Gynaecology, Amsterdam UMC Location AMC, Amsterdam, The Netherlands

Caroline Schneeberger

6 Department of Microbiology, Amsterdam UMC-Locatie AMC, Amsterdam, The Netherlands

7 Center for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands

Associated Data

Introduction.

Symptoms of urinary tract infections in pregnant women are often less specific, in contrast to non-pregnant women where typical clinical symptoms of a urinary tract infection are sufficient to diagnose urinary tract infections. Moreover, symptoms of a urinary tract infection can mimic pregnancy-related symptoms, or symptoms of a threatened preterm birth, such as contractions. In order to diagnose or rule out a urinary tract infection, additional diagnostic testing is required.

The diagnostic accuracy of urine dipstick analysis and urine sediment in the diagnosis of urinary tract infections in pregnant women has not been ascertained nor validated.

Methods and analysis

In this single-centre prospective cohort study, pregnant women (≥16 years old) with a suspected urinary tract infection will be included. The women will be asked to complete a short questionnaire regarding complaints, risk factors for urinary tract infections and baseline characteristics. Their urine will be tested with a urine dipstick, urine sediment and urine culture. The different sensitivities and specificities per test will be assessed. Our aim is to evaluate and compare the diagnostic accuracy of urine dipstick analysis and urine sediment in comparison with urine culture (reference test) in pregnant women. In addition, we will compare these tests to a predefined ‘true urinary tract infection’, to distinguish between a urinary tract infection and asymptomatic bacteriuria.

Ethics and dissemination

Approval was requested from the Medical Ethics Review Committee of the Academic Medical Centre; an official approval of this study by the committee was not required. The outcomes of this study will be published in a peer-reviewed journal.

STRENGTHS AND LIMITATIONS OF THIS STUDY

• The urine of every participating woman will be tested with a set of tests including a urine dipstick, urine sediment and a urine culture.
• We will investigate the course of complaints in pregnant women with a possible urinary tract infection to gain more insight in the diagnostic value.
• The research will be done prospectively; therefore, we expect less bias than in a retrospective cohort.
• It will be a single-centre cohort study, so it could possibly make the participants more homogeneous.

The prevalence of urinary tract infections (UTIs) during pregnancy reported in literature varies between 2.3% and 15%. 1–5 It is hypothesised that anatomical changes during pregnancy such as dilatation of the ureters, decreased ureteral tone and increased bladder volume contribute to urinary stasis and ureterovesical reflux increasing the risk of a UTI. 6–8 Besides the anatomical changes, pregnancy-related glomerular filtration rate increases the alkalinity of the urine and the urinary glucose concentration, which facilitates bacterial growth. 9 The association between UTIs during pregnancy and maternal complications such as hypertensive disorders and caesarean delivery has been reported, although there is contradictory evidence. 4 6 10 Moreover, UTIs during pregnancy have also been associated with neonatal complications such as preterm birth, low birth weight and perinatal death. 2 4 10 In addition, an untreated UTI may lead to pyelonephritis, which further increases the risk of preterm birth. 11 Preterm birth has major consequences at the individual level as well as for society (costs).

In contrast, overtreating pregnant women with antibiotics may also cause harm. Overuse and incorrect use of antibiotics are the main causes of antimicrobial resistance. Moreover, the unnecessary exposure of the unborn child to antibiotics may also not be without risks. Associations between antibiotics during pregnancy and adverse neonatal outcomes including increased risk of cerebral palsy, early-onset sepsis with antibiotic-resistant microorganisms, malformations and epilepsy have been published. 10 12 13 Also, maternal exposure to certain antibiotics is associated with childhood asthma and childhood obesity. 14 15 It is recently found that prenatal exposure to antibiotics can probably lead to alterations in the differential methylation at regulatory regions of imprinted genes. 16 If we can improve diagnostics and related antibiotic prescribing, we possibly can also influence fetal development and possibly long-term health with the results of this study. All of them impact future healthcare costs. Next to that, if we could decrease the number of tests for an accurate diagnosis, costs could be saved.

In the non-pregnant population, a diagnostic test to confirm the diagnosis of UTI is not always considered necessary, since typical clinical symptoms such as dysuria and urgency are regarded distinctive enough. 7 17–20 In pregnancy, the diagnosis of a UTI is less well studied and more challenging. First of all, many women during pregnancy experience symptoms that mimic a UTI such as frequency as a result of pressure of the baby’s head on the bladder. 8 21 On the other hand, symptoms of a UTI can be aspecific in pregnancy; UTIs in pregnant women may solely present with abdominal pain or Braxton Hicks contractions. 9 21 All this makes it more difficult to distinguish between asymptomatic bacteriuria (ASB) and UTI. Furthermore, in pregnancy, ASB can also be present: bacteriuria without any UTI signs or symptoms. ASB is not an active infection and the risk of adverse outcomes like preterm birth is low or absent compared with UTIs. 11 22

Most hospital protocols recommend testing pregnant women for a UTI when they present with symptoms suggestive of UTI or in case of symptoms suspicious of threatened preterm birth. In the diagnostic work-up, various methods are used: urine dipstick test, urine sediments and bacterial cultures, which are used in various ways and come with several limitations.

First, a urine dipstick is a strip with different reagents present. The reagents react on the presence of certain substances, for example, protein, glucose, nitrite and leucocyte esterase. The most important parameters to diagnose UTI on a dipstick are nitrite and leucocyte esterase. Many gram-negative bacteria produce the enzyme nitrate reductase, which converts urinary nitrate into nitrite indicating the presence of bacteria. 23 In the adult population, the sensitivity of nitrite dipstick reported in a systematic review is 0.54 (CI 0.44 to 0.64), the specificity is 0.98 (CI 0.96 to 0.99), positive likelihood ratio of 29.3 (CI 14.4 to 59.7) and a negative likelihood ratio of 0.48 (CI 0.37 to 0.62). Eight out of 14 of the studies included in this review reported on pregnant women, but none of them reported on symptomatic women. 24 Another study shows that the sensitivity and specificity of nitrite to test for ASB in pregnant women are, respectively, 0.55 (95% CI 0.42 to 0.67) and 0.99 (95% CI 0.98 to 0.99). 25

Leucocyte esterase is an enzyme released by neutrophils and macrophages. The leucocyte dipstick has a sensitivity of 0.72 (0.61 to 0.84) and a specificity of 0.82 (0.74 to 0.90), and a positive likelihood ratio of 4.87 (3.26 to 7.29) and a negative likelihood ratio of 0.31 (0.18 to 0.51) in the adult population. 24

Physiological pyuria can appear in pregnant women. 26

Second, for urine sediments, urine samples are centrifuged to obtain a sediment including red and white blood cells, squamous cells and bacteria, which are counted automatically by microscopy. 16 For a UTI, both the presence or absence of leucocytes and bacteria are of interest. A systematic review in the general population reported a sensitivity range of 57.1%–97%, a specificity of 27.0%–97.0%, a positive likelihood ratio of 1.59–24.57 and a negative likelihood ratio of 0.07–0.655 in studies where they used the sediment. 27 Yet again, physiological pyuria can appear in pregnant women. 26 The advantage of the urine sediment over the urine dipstick is that the urine sediment counts all bacteria. The urine dipstick only indicates if there are nitrite-forming bacteria present. However, not all bacteria are uropathogenic.

Finally, the reference test to detect a UTI is a urine culture, which determines bacterial growth. However, the urine dipstick takes a few minutes, the urine sediment about an hour and the urine culture at least 24 hours up to 5 days.

The exact number of bacteria present in urine to define a ‘positive’ urine culture and a UTI is not clear cut. The most common definition is ≥10 5 colony-forming units (CFU)/mL of uropathogens. 28 However, the cut-offs used in practice range from ≥10 3  CFU/mL to ≥10 5  CFU/mL. 18 29 30

The Dutch guideline of obstetrics and gynaecology recommends performing both a nitrite dipstick and a urine culture when pregnant women present with UTI symptoms. In case of a positive nitrite dipstick, treatment should start immediately. In case of a negative nitrite dipstick, treatment should only be started if the culture is positive. The role of the other diagnostic methods is unclear. 9 The Dutch general practitioners’ guideline recommends performing a nitrite dipstick. In case of a positive nitrite dipstick, people will be treated for UTI. Leucocyte esterase test will be performed when the nitrite result is negative. Urine sediments are recommended if leucocyte esterase is present since a positive result of leucocyte esterase is considered as insufficient proof of a UTI. When either the nitrite or the sediment is positive, treatment should be started. When the leucocyte esterase dipstick is negative but there is still a suspicion for a UTI, a sediment is performed additionally. When both urine dipstick and sediment are negative, a UTI is ruled out. If either urine dipstick or sediment results are positive, a urine culture is performed while antibiotics are directly initiated, awaiting the urine culture results. 31

Both in the UK and the USA, guidelines do not state the diagnostic work-up for UTIs in pregnancy (Royal College Obstetricians and Gynaecologist (RCOG) guideline, National Institue for Health and Care Excellence (NICE)guideline and American College of Obstetricians and Gynecologist (ACOG) guideline).

Despite the differences in guidelines, in daily practice, the urine is often only tested with a dipstick. In case of a negative test result, often no additional tests are done. The approach when to perform a sediment or a urine culture is equally ambiguous. There is no clear evidence that the diagnostic accuracy of a standalone dipstick urine (including both the presence of nitrite and leucocyte esterase) is equal to a combined approach of urine dipstick and sediment to diagnose a UTI in pregnancy. Furthermore, pyuria can be present in pregnant women without a UTI. 26 Moreover, the additional value of a urine culture in all women, as recommended by the Dutch guideline of obstetrics and gynaecology, is also unknown. For something as common as a UTI during pregnancy, it is undesirable that the available evidence is too limited to properly inform (diagnostic) guidelines, which results in great diagnostic variation, and potential harmful overtreatment and undertreatment.

This study aims to evaluate the diagnostic accuracy of urine dipstick analysis and urine sediment to bacterial cultures in the diagnosis of UTI in pregnant women.

Study design

This study is a single-centre prospective cohort study.

Participants

All consecutive pregnant women attending the outpatient clinic, the pregnancy ward or emergency department for women’s health in the Amsterdam UMC with symptoms warranting a diagnostic work-up to rule out a UTI can be included, after oral and written consent. These symptoms include dysuria, urgency, frequency, fluid loss, difficulties with voiding, painful voiding, haematuria, or aspecific abdominal pain, (Braxton Hicks) contractions and vaginal blood loss. 7 9

Exclusion criteria are a previous UTI episode in the past 2 weeks, antibiotic use in the past 2 weeks or a structural abnormality of the urogenital tract.

Inclusion of women in the study takes place since 1 November 2021. We plan to include all women in the study in 3 years.

Test methods

The urine samples will be clean-catch midstream urine samples. The index test will be a urine dipstick and a urine sediment. The dipstick that we will use is Clinitek novus 10 (Siemens). The urine sediment will be checked with Atellica 1500 Siemens. For both the urine dipstick and the urine sediment, different cut-offs will be used to investigate which cut-off has the best diagnostic value ( table 1 ).

Expected outcomes

The reference test will be a urine culture.

No blinding will take place for the different tests. The outcome of the test has no influence on the treatment and is necessary for daily practice.

Because of the difficulties to distinguish between ASB and UTI, we will use a different definition for UTI than commonly used. We would like to make sure that we are dealing with a UTI and not ASB.

In this study, a ‘true UTI’ is present when the following three criteria are met:

• Presence of at least two specific or non-specific symptoms of a UTI. 26
• A positive urine culture.
• Symptom improvement during adequate antibiotic treatment, where adequate treatment is defined by proven susceptibility of isolated uropathogens to the administered antibiotic.

The definition of a positive culture is:

• Urine with ≥10 3  CFU/mL of a uropathogen.
• Maximum of two uropathogens ≥10 3  CFU/mL present. When there are more than two uropathogens present of ≥10 3  CFU/mL, the culture will be considered as contaminated.

Next to that, the woman will be asked to fill out a questionnaire. The questionnaire contains questions about risk factors for UTI and possible clinical symptoms of a UTI. After 5–8 days, when the result of the culture will be available, the woman will be called to evaluate the presenting symptoms. This check-up is part of standard care. Both the woman and the clinician have access to the test result; it is not blinded. Women will be asked permission to collect data from the midwife, gynaecologist or general practitioner about their pregnancy and delivery.

The statistical analysis will be performed using IBM SPSS Statistics V.26.

Primary outcome

We will determine which combination of leucocyte esterase, nitrite presence in the dipstick and bacteria presence and leucocyte count in the sediment yield the best performance of both methods separately and combined to predict a ‘true UTI’ according to our definition. Different cut-offs and combinations of cut-offs of the urine analysis components will be explored to calculate sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios ( table 1 ). In addition, we aim to develop a diagnostic model based on all available evidence on leucocyte esterase, nitrite presence, bacteria presence, leucocyte count and symptoms.

After the best performing cut-offs for both urine dipstick and urine sediment have been determined, we will compare the performance of these two tests together in terms of sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios. Urine culture will be used as the reference test. The performance will be compared with the predefined ‘true’ UTI. To do this, we first select all true positives and true negatives using the reference test. In addition, we compare the classifications of urine dipstick with urine sediment in a 2×2 table for true positives (sensitivity) and a 2×2 table for true negatives (specificity) and calculate a p value for the difference in classification using a paired McNemar test.

Planned sensitivity analyses will also be performed for different cut-off values for pathogens in urine cultures ≥10 3  CFU/mL, ≥ 10 4  CFU/mL and ≥10 5  CFU/mL.

Contaminated urine cultures will be considered as negative cultures.

Secondary outcome

We will evaluate which clinical symptoms are best at predicting a UTI in pregnancy and which symptoms are not. The symptoms of a UTI will be studied with incidences and p values to identify which symptoms are associated with UTI.

To identify risk factors for UTI, univariate logistic regression will be used. In case it is possible, multivariate logistic regression will be used to identify the risk factors. We will use a forward stepwise selection for our regression model.

Pregnancy duration will be measured in weeks and days of gestational age and will be compared between women with and without UTI with a Student’s t-test.

The timing of the performed urine test (urine dipstick, urine sediment and urine culture) and the gestational age of delivery will be noted. Time between diagnosis of UTI and delivery will be compared using Kaplan-Meier survival curve.

Power analysis

To provide an estimated sample size, we calculated the sample sizes necessary for 80% power in a McNemar paired test comparing urine dipstick with urine sediment in women with true-positive UTI (sensitivity) and true-negative UTI (specificity). The expected discrepant cells for sensitivity are 14% and 5%, with a calculated 181 true-positive cases necessary for 80% power. The expected discrepant cells for specificity are 10% and 4% with a calculated 302 true-negative cases necessary for 80% power. We expect that around 30% of the included women will have a UTI such that the necessary sample size to include is 603 for sensitivity and 432 for specificity.

With a 10% expected drop-out, the sample size would be 660 pregnant women.

Data will be collected using Castor, which is an application system that enables collection and clean-up of trial data using the internet. Data handling will be done coded. The data will be saved for 15 years.

Patient and public involvement

There was no patient or public involvement in this research.

Approval was requested from the Medical Ethics Review Committee of the Academic Medical Centre; an official approval of this study by the committee was not required (METC review number W21_291 #21.318). All participants will give written and oral informed consent prior to entry to the study and will be made aware that participation is strictly voluntary.

The outcomes of this study will be published in a peer-reviewed journal.

The diagnostic accuracy of a urine dipstick and, less often, a urine sediment for the diagnosis of bacteriuria in pregnancy has been evaluated. 23 32 However, no studies are available in pregnant women on the diagnostic accuracy of symptomatic UTIs. As a result, different guidelines in the Netherlands advise different ways of testing for UTIs in pregnant women. International guidelines lack any recommendations on specific urine tests. However, in pregnant women with a UTI, both undertreatment and overtreatment are potentially harmful; therefore, correct diagnosis is very important.

The focus of this study is the diagnostic work-up. We will not intervene in the treatment given or follow-up provided to the participating women. It is likely that certain types of bias will be introduced as a result of implementation of this study. Bias could be introduced because more diagnostics will be performed and all three urine test results will be reported to the treating clinician (not blinded). Since more result will be available, this could affect the prescription of antibiotics.

We do not expect a lot of women with partial verification bias since the three different urine tests will be most of the time executed at the same time from the same urine sample. Because of this, we avoid that only the urine dipstick and/or sediment is performed and the urine culture is not executed.

The urine culture has been used, both in daily practice and in research, for a long time. There are no logical alternative reference standards. The urine culture has been proven to be effective. We do not expect an inappropriate reference standard.

Since the result of the urine culture is only available a few days after the results of the urine dipstick and sediment, we do not expect a review bias.

Clinical impact

Due to the different cut-offs to report uropathogens and their susceptibilities (10 3 instead of 10 4 ), the rate of prescribing antibiotics may increase too. However, the result of the culture will only come in after a few days, so the decision to start antibiotics has most likely already been made. With this study, we hope to provide either better evidence for the current advice in guidelines and/or guide necessary adjustments.

To avoid unnecessary treatments, diagnostic tests and costs, and to minimise possible harmful neonatal outcomes, the diagnostic process of UTIs should be optimised. This new workflow should be implemented in the daily care to create a more evidence-based treatment strategy. Since the diagnostic work-up for UTIs takes place on a daily basis, the results of this research will have a major impact on daily routine care. To find an optimal strategy for diagnosing a UTI is only the start of tackling the challenges around the diagnosis of UTIs in pregnancy.

Supplementary Material

Contributors: DEW wrote the proposal and the manuscript. BMK initiated the research, and critically revised the proposal and manuscript. EvL critically revised the proposal and manuscript. MCFJdR critically revised the manuscript. SDK critically revised the proposal and manuscript. EP critically revised the proposal and manuscript. CS critically revised the proposal and manuscript. All authors read and approved the final manuscript.

Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests: None declared.

Patient and public involvement: Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

Provenance and peer review: Not commissioned; externally peer reviewed.

Ethics statements

Patient consent for publication.

Not required.

Please note:  This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

Am Fam Physician. 2004;69(1):157

What is a urinary tract infection?

Urinary tract infections (UTIs) are caused by bacteria (germs). The most common kind of UTI is a bladder infection. Other kinds of UTIs are kidney infections and infections of the urethra. The urethra is the small tube that goes from the bladder to the outside of your body.

How do I know I have a UTI?

UTIs may cause different symptoms in different people. You may feel a burning sensation when you urinate. You may need to urinate more often, sometimes every 30 to 60 minutes. Or, you may feel like you need to go again right after you have just urinated. You may notice blood in your urine or a strong smell.

Sometimes germs grow in the urinary tract but you do not have any of these symptoms. This is called asymptomatic bacteriuria (say this: “a-simp-toe-mat-ik bac-tear-ee-you-ree-ah”). Your doctor can test to find out if you have this. Asymptomatic bacteriuria should be treated in pregnant women but does not have to be treated in most other women.

How will a UTI affect my baby?

If you have a UTI and it is not treated, it may lead to a kidney infection. Kidney infections may cause early labor. Fortunately, asymptomatic bacteriuria and bladder infections usually can be found and treated before the kidneys get infected. If your doctor treats a UTI early and properly, the UTI will not hurt your baby.

How are UTIs treated?

Your doctor will prescribe a medicine that is safe for you and the baby. You can help by drinking a lot of water to help flush the germs out of your urine.

How do I know if the medicine is not working?

If you have a fever (higher than 100.5°F), chills, pain in your lower stomach, nausea, vomiting, or pain in your sides, you should call your doctor. You should call your doctor if you have any contractions, or if, after taking medicine for three days, you still have a burning feeling when you urinate.

Can I keep this from happening again?

You can help prevent UTIs in several ways. You should take any medicines just as your doctor says to. Also, drink plenty of fluids every day (water is the best), and urinate often. Do not hold your urine for a long time.

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