Screen only pregnant women routinely for asymptomatic bacteriuria: USPSTF

The U.S. Preventive Services Task Force (USPSTF) recommends screening pregnant women for asymptomatic bacteriuria (ASB) but not nonpregnant women or men. These recommendations form the basis of a draft recommendation statement published by the USPSTF.

The U.S. Preventive Services Task Force is still advising that clinicians screen pregnant women for asymptomatic bacteriuria, but it's downgraded the strength of the recommendation from grade A to grade B.

Researchers at Kaiser Permanente Center for Health Research in Portland, Oregon,conducted a systematic review on the benefits and harms of screening for ASB and treatment for pregnant women, nonpregnant women, and men. Data were included from 19 studies of screening or treatment of ASB; 14 were conducted among pregnant women. Two studies on pregnant women examined the effectiveness and/or harms of screening (5,289 women) and 12 examined the effectiveness and harms of treatment (2,377 women). Five studies examined the effectiveness and harms of treatment in nonpregnant women and men (777 adults), focusing mainly on women.

Asymptomatic bacteriuria is defined as the presence of bacteria in the urine of a person without signs or symptoms of a urinary tract infection.Among the general adult population, women (across all ages) have the highest prevalence of asymptomatic bacteriuria, although rates increase with age among both men and women.The reported prevalence of asymptomatic bacteriuria ranges from 1% to 6% among premenopausal women to 22% among women older than age 90 years.Asymptomatic bacteriuria is present in an estimated 2% to 10% of pregnant women.The condition is considered rare in men.

During pregnancy, physiologic changes affecting the urinary tract are believed to increase the risk of asymptomatic bacteriuria and symptomatic urinary tract infections, including pyelonephritis (a urinary tract infection in which one or both kidneys become infected). Pregnant women have a higher rate of hospitalization for pyelonephritis than nonpregnant women. Pyelonephritis is associated with perinatal complications including septicemia, respiratory distress, low birth weight, and spontaneous preterm birth.

The presence of asymptomatic bacteriuria has not been shown to increase the risk of negative health outcomes among nonpregnant persons.

In 2008, the task force gave its strongest recommendation to screening in pregnant women, concluding with high certainty that the net benefit in terms of preventing perinatal complications was "substantial." Now, the group classifies the benefit as "no greater than moderate." Among the reasons for the change: In recent decades, pyelonephritis has only rarely occurred among pregnant women with untreated asymptomatic bacteriuria. Additionally, the harms of treating screen-detected asymptomatic bacteriuria — including antibiotic side effects and bacterial resistance — are "at least small."

As in 2008, the group continues to recommend against screening in nonpregnant adults (grade D recommendation).

Both recommendations are still in draft form. The public may comment on them until May 20 at the fourth link below.