Accuracy of Amsel's Criteria in the Diagnosis of Bacterial Vaginosis (Preliminary Report)

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge in fertile women. Although the gram staining of vaginal discharge (Nugent score) is believed to be the gold standard for diagnosis BV but Amsel's criteria are recommended for the clinical diagnosis of BV. The aim of this study was to determine the role of each of Amsel's criteria in the diagnosis of BV. This descriptive cross-sectional study was performed on 69 women with abnormal vaginal discharge. Samples of vaginal discharge were tested for BV infection using both Amsel's criteria and Nugent score. Considering Nugent score as the gold standard sensitivity, specificity, positive and negative likelihood ratio, positive and negative predictive value, area under curve of each Amsel's criteria and combinations of two criteria were estimated. The prevalence of BV was 42% in our study. Vaginal pH and clue cell were the criteria with the highest sensitivity (83%) and specificity (84%), respectively. Also the sensitivity and specificity of combination of any two criteria ranged from 24% to 62% and 70% to 87%, respectively. The sensitivity and specificity of Amsel's criteria was 55% and 73% respectively. In this study we compared the results of combination of two of Amsel's criteria for diagnosis of BV while the Nugent score was considered as the gold standard. The findings of the present study showed that we can use pH of vaginal discharge for the diagnosis of bacterial vaginosis at first and if the result is negative, the diagnosis can be ruled out. If the pH test becomes positive, another component of Amsel should be tried while two positive components confirm the diagnosis of BV and specific treatment could be started. If the second component is negative we should use another component of Amsel for diagnosis or ruling out of the disease.