Risk score for antenatal bacterial vaginosis: BV PIN points

Abstract

Objective: Develop a clinical risk score to screen for antenatal bacterial vaginosis (BV), irrespective of symptoms.

Study design: Cohort study of 913 pregnant women with last menstrual periods between January 30, 1995 and February 22, 1997. BV was evaluated by Nugent-scored vaginal smears (scores of 7 to 10 considered positive) between 24 and 29 weeks' gestation. Forty-four potential risk factors were assessed.

Results: 17.8% of women had BV, of whom 22% were screened for BV by the usual care provider. Logistic regression-adjusted analyses found six predictors: vaginal pH>4.5 (OR=11.6, 95% confidence interval [CI] [7.8, 17.2]); black race (OR=1.9, 95% CI [1.3, 2.8]); condom use during pregnancy (OR=1.6, 95% CI [1.0, 2.5]); antenatal BV (OR=1.7, 95% CI [1.0, 2.8]); absence of sperm on smear (OR=1.7, 95% CI [1.0, 2.9]); and no history of sexually transmitted diseases (OR=1.6, 95% CI [1.0, 2.5]). Risk score weights were 5 for an elevated vaginal pH and 1 otherwise. The sensitivity and specificity of screening women with scores > or =4 were both 77%; this would involve screening 33% of patients.

Conclusion: Approximately 80% of our BV cases were asymptomatic, emphasizing the need for objective risk assessment. Using six factors, clinicians can identify pregnant women at risk for BV.