Am Fam Physician. 2010;81(4):505-506
Summary of Recommendations and Evidence
The U.S. Preventive Services Task Force (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 (Table 1). A recommendation.
The USPSTF recommends against screening for asymptomatic bacteriuria in men and nonpregnant women. D recommendation.
| Population | All pregnant women | Men and nonpregnant women |
| Recommendation | Screen with urine culture | Do not screen |
| Grade: A | Grade: D | |
| Detection and screening tests | 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, in a midstream clean-catch specimen, is considered a positive test result. | ||
| Screening intervals | A clean-catch urine specimen should be collected for screening culture at 12 to 16 weeks' gestation or at the first prenatal visit, if later. | Do not screen. |
| The optimal frequency of subsequent urine testing during pregnancy is uncertain. | ||
| Benefits of detection and early treatment | The detection and treatment of asymptomatic bacteriuria with antibiotics significantly reduces the incidence of symptomatic maternal urinary tract infections and low birth weight. | 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 of asymptomatic bacteriuria include adverse effects from antibiotics and the development of bacterial resistance. | |
| Other relevant recommendations from the USPSTF | Additional USPSTF recommendations involving screening for infectious conditions during pregnancy can be found at http://www.ahrq.gov/clinic/cps3dix.htm#obstetric and http://www.ahrq.gov/clinic/cps3dix.htm#infectious. | |
Rationale
Importance.In pregnant women, asymptomatic bacteriuria has been associated with an increased incidence of pyelonephritis and low birth weight (less than 2,500 g [5 lb, 8 oz]).
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, 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 (UTIs) and low birth weight.
In men and nonpregnant women, adequate evidence suggests that screening men and non-pregnant 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.
Clinical Considerations
Patient population. This recommendation applies to the general adult population, including adults with diabetes mellitus. The USPSTF did not review evidence for screening certain groups at high risk of severe UTIs, such as transplant recipients, patients with sickle cell disease, and patients with recurrent UTIs.
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.1 Urine culture is the standard criterion 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.2
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 urinary specimen for a screening culture at 12 to 16 weeks' gestation or at the first pre-natal visit, if later. The optimal frequency of subsequent urine testing during pregnancy is uncertain.
