Comparison of Gram and Kopeloff stains in the diagnosis of bacterial vaginosis in pregnancy

Bacterial vaginosis (BV) is commonly diagnosed by using the Nugent score, a semiquantitative scoring system to evaluate bacterial morphotypes on Grain stain of vaginal secretions. Some authors have suggested using the Kopeloff modification of the Grain stain. Asymptomatic BV in pregnancy has been associated with adverse outcomes. We performed both stains on simultaneously collected vaginal smears froth 2652 women at 24-26 weeks of gestation. Gram staining gave significantly higher (more abnormal) Nugent scores than Kopeloff staining. Compared to the Kopeloff stain, the number of specimens graded as indeterminate or consistent with BV by Gram stain increased by 29% (469 versus 364, P <.001). Interrater reliability of the Nugent score (n = 413) for Kopeloff staining was significantly better than Grain staining (agreement = 74% versus 63%, intraclass correlation coefficient = 0.87 versus 0.79, P <.05, 95% confidence intervals 0.85-0.89 and 0.75-0.82, respectively). (C) 2006 Elsevier Inc. All rights reserved.