USPSTF: Don't Routinely Screen Pregnant Women for Bacterial Vaginosis

Primary care physicians should not screen asymptomatic pregnant women at low risk for preterm delivery for bacterial vaginosis, according to guidance recently issued by the U.S. Preventive Services Task Force, or USPSTF. The task force also concluded that currently available evidence is insufficient to assess the balance of benefits and harms of screening for bacterial vaginosis in asymptomatic pregnant women at high risk for preterm delivery. The recommendations and supporting documents are available online.

The guidance related to pregnant women at low risk for preterm delivery is a grade "D" recommendation, which means that the USPSTF recommends against the service because there is a "moderate or high certainty that the service has no benefit or that the harms outweigh the benefits." In this case, the USPSTF found that no direct evidence indicates screening for bacterial vaginosis reduces adverse health outcomes in these women; good evidence suggests that treatment of the condition in these women lacks benefit.

The guidance related to pregnant women at high risk for preterm delivery is considered an "I" statement, meaning that the USPSTF has concluded "that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined." Again, the task force found no direct evidence indicating that screening for bacterial vaginosis reduces adverse health outcomes in these women; and evidence from good-quality studies on the benefits of treating the condition is conflicting.

The USPSTF found only poor evidence regarding potential harms of screening for bacterial vaginosis in either group of pregnant women; studies in this area were lacking. However, task force members found fair evidence that false-positive results from screening asymptomatic women at low risk for preterm delivery can lead to harms associated with treatment. They found conflicting evidence regarding the harms of treating the condition in asymptomatic women at high risk for preterm delivery.

According to the "Clinical Considerations" section of the USPSTF recommendation statement, specific risk factors for preterm delivery include "African-American race or ethnicity," low body mass index, vaginal bleeding, previous preterm delivery, pelvic infection and bacterial vaginosis. Bacterial vaginosis, the most common lower genital tract syndrome among women of reproductive age, is most frequently seen in black women, women of lower socioeconomic status and those who previously have delivered low-birthweight babies.

Studies have documented an association between bacterial vaginosis and preterm delivery, and it is this epidemiologic evidence that for years had been used as a rationale for screening asymptomatic pregnant women for the disease -- despite the fact that as many as half of all cases resolve spontaneously during pregnancy.