Asymptomatic Bacteriuria in Pregnancy

Comments from Expert Advisory Committee

  • Asymptomatic bacteriuria is the presence of 1 or more species of bacteria growing in the urine at a quantitative count of >105 colony-forming units/mL, without signs or symptoms attributable to urinary tract infection.
  • Asymptomatic bacteriuria occurs in 2% to 7% of pregnant women.
  • Antibiotic treatment of asymptomatic bacteriuria reduces the risk of pyelonephritis, low birth weight and premature labour.
  • A urine culture is usually requested early in pregnancy (12-16 weeks).
  • The presence of asymptomatic bacteriuria should be confirmed by two consecutive urine cultures (preferably within two weeks).
  • Urine culture remains the gold standard in detection of asymptomatic bacteriuria.
  • Dipstick testing is not sufficient to screen for bacterial UTIs in pregnancy.
  • A positive urine culture for bacteriuria in the second sample of urine should be treated with an appropriate antibiotic for the bacteria isolated and the trimester of pregnancy.
  • Confirm clearance with urine culture after treatment.
  • Repeat urine cultures at subsequent antenatal visits may be required for prior recurrent UTI’s, diabetes mellitus, renal anomaly.
  • Trimethoprim should not be prescribed for pregnant women with established folate deficiency, low dietary folate intake, or women taking other folate antagonists.


ABin Pregnancy table jan 28

Patient Information

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Reviewed Jan 2021