Diagnosis of bacterial vaginosis in the pregnant patient in an acute care setting

Abstract

Objective

To determine the accuracy of clinical criteria relative to Nugent’s criteria for diagnosing bacterial vaginosis (BV) in the pregnant patient.

Methods

This prospective study was conducted in pregnant patients requiring a speculum examination in an ER triage system. Determination was made of vaginal pH, whiff test, clue cells and discharge for use with Amsel’s criteria. Diagnosis of BV was made using Nugent’s criteria. Data were analyzed with Student’s t and chi square statistics.

Results

Samples by Nugent’s criteria were positive for 32 women out of a sample size of 193 (16.6%). There were no significant differences in chief complaints between women with and without BV. Significantly more women with BV reported odor, but there were no other significant differences in symptoms between women with and without BV. Patients with BV were significantly less likely to have a white discharge. The whiff test was not reported in many cases, however, when a test was recorded, women with BV were significantly more likely to have a positive test. Approximately 50% of the women with BV had either ≥20% clue cells or pH > 4.5; only 25% had both. Sensitivities of pH > 4.5, pH ≥ 4.5, ≥20% clue cells, whiff test and the combination of high pH and clue cells were low (22–81%). Specificities of individual and combined criteria ranged from 68 to 99%. The negative predictive power of pH < 4.5 was 95%; 113 women had a pH less than 4.5 and of these women, 107 did not have BV.

Discussion

The negative predictive power of a pH < 4.5 is very high, and the majority of women fell into this category. An algorithm for pregnant women could therefore be constructed that would call for pH to be tested. Women with a pH < 4.5 would not receive treatment or undergo further testing. The minority of women with a pH ≥ 4.5 would then undergo testing with the Gram stain using Nugent’s criteria.