Screening for bacteriuria in pregnant women: Benefit unclear

Due to a lack of suitable studies, no conclusions can be drawn on the patient-relevant benefit or harm of screening for asymptomatic bacteriuria (ASB) in pregnant women. The benefit of antibiotic treatment of ASB following screening is also an open issue, as the results of the over 40-year-old studies cannot be applied to the current healthcare situation. This is the result of the final report published by the German Institute for Quality and Efficiency in Health Care (IQWiG) on 23 April 2015, which was commissioned by the Federal Joint Committee (G-BA).

Maternity guidelines specify routine screening for ASB

In ASB, the bacteria in the urine do not cause symptoms of a urinary tract infection; ASB can thus be detected only by tests. The midstream urine of pregnant women is usually tested. According to old studies, untreated ASB leads to a kidney infection (pyelonephritis) in about a quarter of cases. A link may also exist between bacteriuria and an increased risk of preterm birth.

To evaluate the benefit of screening for ASB for the mother and the child, it would seem reasonable to compare this strategy with a management strategy without screening. In Germany, like in many other countries, screening for ASB has been a fixed component of antenatal screening for many years due to its alleged benefit. This is why no such comparative study could be identified. Alternatively, the Institute investigated the benefit and harm of treatment of ASB detected by screening compared with non-treatment or placebo. If the benefit of such treatment in affected women were proven, at least the basic precondition for a benefit of screening would be fulfilled.

Healthcare situation has changed

Three studies on this question published between 1960 and 1969 were identified. The most important patient-relevant outcomes were neonatal morbidity, pyelonephritis, and lower urinary tract infection. For the two latter outcomes, in each case a hint of an effect of antibiotic treatment was found.

But these over 40-year-old study results are not applicable to the current healthcare situation. In part, before the study the participants were subjected to measures that are no longer common in healthy pregnant women and that could have influenced the treatment effect. It part it remains unclear how ASB was determined, so that effects cannot be clearly allocated to a diagnostic procedure. In addition, in all studies information on the main characteristics of the study populations is missing, which makes the interpretation of results more difficult.

Pregnancy causes numerous changes in the woman’s body. Hormonal and mechanical changes increase the risk of urinary stasis and vesicoureteral reflux. These changes, along with an already short urethra (approximately 3-4 cm in females) and difficulty with hygiene due to a distended pregnant belly, increase the frequency of. Indeed, UTIs are among the most common bacterial infections during pregnancy.