Evidence on the benefits and harms of screening and treating pregnant women who are asymptomatic for bacterial vaginosis: an update review for the U.S. Preventive Services Task Force.

BACKGROUND: Bacterial vaginosis is the most common lower genital tract syndrome among women of reproductive age. There has been continued debate about the value of screening and treating asymptomatic pregnant women for bacterial vaginosis.
PURPOSE: To examine new evidence on the benefits and harms of screening and treating bacterial vaginosis in asymptomatic pregnant women. DATA SOURCES: English-language studies on Ovid MEDLINE (2000 to September 2007) and Cochrane Library databases (through September 2007), reference lists, and expert suggestions. STUDY SELECTION: Screening, treatment, or adverse effect studies with pregnancy outcome data in women who are asymptomatic for bacterial vaginosis. DATA EXTRACTION: Study and patient characteristics, treatment variables, adverse pregnancy outcomes, and internal validity quality criteria from the U.S. Preventive Services Task Force (USPSTF) and Jadad scale were abstracted. DATA SYNTHESIS: 7 new randomized, controlled treatment trials and 2001 report data were combined in a series of meta-analyses to estimate the pooled effect of treatment on preterm delivery (<37, <34, and <32 weeks); low birthweight; and preterm, premature rupture of membranes. LIMITATIONS: No screening studies that compared a screened population with a nonscreened population were found. Significant heterogeneity was found among the high-risk treatment trials (P < 0.001). It is not clear from the detailed description of the studies which factors explain the differences in preterm delivery rates and potentially the association of treatment effect; however, both raise concern for the unintended potential for harm.
CONCLUSION: No benefit was found in treating women with low- or average-risk pregnancies for asymptomatic bacterial vaginosis. More research is needed to better understand these groups and the conditions under which treatment can be harmful or helpful, and to explore the relevance of bacterial vaginosis to other adverse pregnancy outcomes, such as delivery before 34 weeks.