The impact of regular vaginal pH screening on the diagnosis of bacterial vaginosis in pregnancy

BACKGROUND - Bacterial vaginosis has recently been associated with preterm labor and delivery. The purpose of our study was to determine whether regular prenatal vaginal pH testing resulted in more frequent diagnoses of bacterial vaginosis and other vaginal infections, more frequent treatment with antibiotics, and fewer preterm deliveries. We also sought to determine the sensitivity and specificity of pH testing and vaginal symptom reporting in identifying vaginal infections. METHODS - Our study was a prospective clinical trial involving 121 pregnant women randomized to receive either standard prenatal care, including routine inquiry about vaginal symptoms, or standard care supplemented by vaginal pH testing. Women with symptoms or a vaginal pH level >4.5 received a wet mount examination. Confirmed infections were treated according to study protocols. RESULTS - Women who received regular pH testing showed significantly higher detection rates for bacterial vaginosis than controls (48.4% vs 27.1%, P = .015) and more frequent detection of Trichomonas vaginalis (7.8% vs 1.7%, P = .116). A higher percentage of women in the experimental group were treated for bacterial vaginosis and trichomoniasis (46.9% vs 27.1%, P = .024), and the preterm birth rate was one half that of the control group (4.7% vs 10.2%, P = .243). The presence of vaginal symptoms or a vaginal pH level >4.5 identified bacterial vaginosis or trichomoniasis with 84.4% sensitivity. CONCLUSIONS - In our study, frequent vaginal pH testing during pregnancy resulted in more frequent diagnosis and treatment of bacterial vaginosis. Since vaginal symptoms and elevated pH levels appear to be useful in screening for bacterial vaginosis and trichomoniasis, frequent pH testing should be evaluated in larger studies.