Asymptomatic Bacteriuria in Pregnancy—Clinician FAQ

We recommend screening pregnant women for asymptomatic bacteriuria once during the first trimester with urine culture. (Weak recommendation; very low quality evidence).

This recommendation applies to pregnant women who are not experiencing symptoms of a urinary tract infection and who are not at increased risk for asymptomatic bacteriuria.

1. Who is at increased risk for asymptomatic bacteriuria?

  • Women with diabetes, recurrent urinary tract infections, polycystic kidneys, other kidney defects from birth, and sickle cell disease are at higher risk for asymptomatic bacteriuria and associated complications for mothers and babies.

2. What are some considerations for implementing this recommendation?

  • Patient preferences
    • Screening decisions are influenced by how women weigh possible benefits of preventing infection against potential harms of taking antibiotics during pregnancy.
  • Timing
    • For ease of implementation, we recommend one-time screening in the first trimster.
    • However we recognize that not all patients will present for prenatal care during their first trimester and that screening may occur after the first trimester.

3. What are the benefits and harms of screening for asymptomatic bacteriuria in pregnancy?

  • Screening 1,000 pregnant women will potentially result in 1 to 5 fewer babies born with low birth weight (<2500 g).
  • Screening 1,000 pregnant women will potentially result in 4 to 16 fewer women developing a kidney infection.
  • Only limited and very low quality evidence is available to infer harms associated with screening and treatment of asymptomatic bacteriuria for women and their babies.

4. Why is it a weak recommendation?

  • The recommendation is weak because of uncertainty regarding the benefits of screening as well as the various preferences of women regarding antibiotic treatment in pregnancy.
  • A weak recommendation for screening places a relatively higher priority on the small but uncertain benefit of screening for asymptomatic bacteriuria and a relatively lower priority on the lack of evidence regarding serious harms associated with antibiotic use for pregnant mothers and their babies.

5. What does a weak recommendation mean?

  • A weak recommendation in favour of screening highlights the need for shared decision-making with patients because many will want to be screened, but some will not.

6. What do you do with a positive test result?

  • Treatment of a positive urine test should be guided by results of the urine culture and sensitivity.