Prevalence of bacterial vaginosis in pregnant women and predictive value of clinical diagnosis

To study the prevalence of bacterial vaginosis (BV) in pregnant women and to evaluate the accuracy of clinical criteria for the diagnosis of BV. In this observational study 502 asymptomatic pregnant women were screened for bacterial vaginosis in a rural health care facility by Gram stain. Accuracy of clinical diagnosis using individual and two of Amsel's criteria was evaluated. The frequency of BV was 8.6% by Nugent's method. For Amsel's criteria, sensitivity and specificity was 51.2 and 98%, with 71% PPV and 95.5% NPV. The most sensitive individual criterion was vaginal pH, but with lowest specificity. The criterion with highest specificity was clue cells. The combination of the two criteria, vaginal pH and positive amine test, had best positive and negative predictive values 60.5 and 97.8%, respectively. The diagnosis of BV according to Amsel's criteria may be simplified using a combination of the two criteria, vaginal pH and amine test, in settings where microscopy or Gram staining is not available.