Diagnosis of bacterial vaginosis: Comparison of Nugent and novel microscopic method

Abstract

Background/Aim: Bacterial vaginosis (BV) is common cause of vaginal discomfort in women. The aim of this study was comparison of Nugent's scoring system and novel microscopy method, introduced in our laboratory and used in BV diagnosis. Methods: 705 pregnant and asymptomatic women between 24 and 28 weeks of pregnancy participated in this prospective study. Degree of agreement between methods was determined by kappa index. Sensitivity, specificity, positive and negative predictive value of novel microscopy method was compared to Nugent's score as standard. Results: Based on scoring system of both methods, Nugent and novel microscopy method, BV was diagnosed in 21%, and 25% of women, respectively. Despite the disparities among diagnostic criteria, which mainly concerned classification of intermediary samples, the degree of agreement between categories, determined by kappa index, was satisfactory: Nugent vs novel microscopy method (?=0,68; good agreement), and Nugent vs novel microscopy method without intermediary results (?=0,83; very good agreement). We also demonstrated that compared to Nugent, as golden standard, novel microscopy method had high sensitivity and specificity (ranging from 75%-99.3%), and positive and negative predictive values (ranging from 88.8%-99.5%). Conclusion: novel microscopy method in diagnosis of BV, corresponded well with Nugent's scoring system which allows it to be an alternative method in diagnosing of BV. Our method is based on relative number of bacterial morphotypes, either rod forms (? 1.5?m, lactobacilli) or non-rod forms (< 1.5?m, bacterial vaginosis associated bacteria) under 200x magnification, which extends the surface of examined preparation, but without prolongation of observer's working time. Furthermore, novel microscopy method appeared to be flexible and can be reorganized in the way to categorize findings into only two groups: normal and BV, which makes it comparable to dichotomous Amsel's clinical criterion.