Asymptomatic Bacteriuria: Screening -- Pregnant Women


General

Grade: A The USPSTF recommends the service. There is high certainty that the net benefit is substantial. Offer or provide this service.

Specific Recommendations

The USPSTF recommends screening for asymptomatic bacteriuria with urine culture for pregnant women at 12 to 16 weeks' gestation or at the first prenatal visit, if later.

Frequency of Service

All pregnant women should provide a clean-catch urine specimen for a screening culture at 12 to 16 weeks' gestation or at the first prenatal visit, if later. The optimal frequency of subsequent urine testing during pregnancy is uncertain.

Risk Factor Information

No information available.


Clinical

Patient Population
This recommendation applies to the general adult population, including adults with diabetes. The USPSTF did not review evidence for screening certain groups at high risk for severe urinary tract infections, such as transplant recipients, patients with sickle cell disease, and patients with recurrent urinary tract infections.

Screening Tests
The screening tests used commonly in the primary care setting (dipstick analysis and direct microscopy) have poor positive and negative predictive value for detecting bacteriuria in asymptomatic persons. Urine culture is the gold standard for detecting asymptomatic bacteriuria but is expensive for routine screening in populations with a low prevalence of the condition. However, no currently available tests have a high enough sensitivity and negative predictive value in pregnant women to replace the urine culture as the preferred screening test.

Treatment
Pregnant women with asymptomatic bacteriuria should receive antibiotic therapy directed at the cultured organism and follow-up monitoring.

Screening Intervals
All pregnant women should provide a clean-catch urine specimen for a screening culture at 12 to 16 weeks' gestation or at the first prenatal visit, if later. The optimal frequency of subsequent urine testing during pregnancy is uncertain.

Rationale


Importance: In pregnant women, asymptomatic bacteriuria has been associated with an increased incidence of pyelonephritis and low birthweight (birthweight <2500 g).

Detection: Asymptomatic bacteriuria can be reliably detected through urine culture. The presence of at least 105 colony-forming units per mL of urine, of a single uropathogen, and in a midstream clean-catch specimen is considered a positive test result.

Benefits of Detection and Early Intervention: In pregnant women, convincing evidence indicates that detection of and treatment for asymptomatic bacteriuria with antibiotics significantly reduces the incidence of symptomatic maternal urinary tract infections and low birthweight.

In men and nonpregnant women, adequate evidence suggests that screening men and nonpregnant women for asymptomatic bacteriuria is ineffective in improving clinical outcomes.

Harms of Detection and Early Treatment: Potential harms associated with treatment for asymptomatic bacteriuria include adverse effects from antibiotics and development of bacterial resistance. Without evidence of benefits from screening men and nonpregnant women, the potential harms associated with overuse of antibiotics are especially significant.

USPSTF Assessment: The USPSTF concludes that 1) in pregnant women, there is high certainty that the net benefit of screening for asymptomatic bacteriuria is substantial, and 2) in men and nonpregnant women, there is moderate certainty that the harms of screening for asymptomatic bacteriuria outweigh the benefits.


Others

Recommendations of Others The American Academy of Family Physicians strongly recommends that all pregnant women be screened for asymptomatic bacteriuria using urine culture at 12 to 16 weeks' gestation or at the first prenatal visit if after that time. The Infectious Diseases Society of America recommends screening pregnant women for asymptomatic bacteriuria with a urine culture "at least once" in early pregnancy. It also states that screening for asymptomatic bacteriuria in nonpregnant women, diabetic women, or community-dwelling or institutionalized older persons is not indicated. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommend screening for asymptomatic bacteriuria "early in pregnancy, as appropriate". The American College of Obstetricians and Gynecologists recommends screening for asymptomatic bacteriuria in nonpregnant women with diabetes mellitus.


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