Wet smear compared with gram stain diagnosis of bacterial vaginosis in asymptomatic pregnant women

Objective: To compare wet smear and Gram stain diagnoses of bacterial vagin osis among asymptomatic pregnant women. Methods: Between November 1, 1996 and December 31, 1997, asymptomatic women who initiated prenatal care in our obstetric clinics were invited to parti cipate. Exclusion criteria included antimicrobial use within 2 weeks, cervi cal cerclage, vaginal bleeding, placenta previa, spermicide use, douching, or intercourse within 8 hours. Clinical diagnosis that required two of thre e positive criteria for bacterial vaginosis (vaginal pH, whiff test, and cl ue cells on wet smear) was compared with Gram stain diagnosis (Bacterial va ginosis score 7-10 by Nugent criteria). Results: Population characteristics (n = 69) included an average (+/- stand ard deviation [SD]) maternal age of 27.3 +/- 6.6 years, 26 nulliparas (38%) , 28 black women (41%), 23 white women (38%), 15 Hispanic women (22%), and three Asian women (4%). The mean (+/-SD) gestational age at entry was 15.6 +/- 7.6 weeks. Twenty-seven percent (18 of 67) of the study population was diagnosed with bacterial vaginosis by definitive Gram stain. Two slides wer e lost or were of poor quality and not included. Using Gram stain diagnosis of bacterial vaginosis as the standard, clinical diagnosis had sensitivity of 56% (95% confidence interval [CI] 32%, 78%), a specificity of 96% (95% CI 90%, 100%), a positive predictive value of 83%, and a negative predictiv e value of 85%. Conclusion: In asymptomatic pregnant women, bacterial vaginosis can be diag nosed reliably by Gram slain. (Obstet Gynecol 2000;96:504-6. (C) 2000 by Th e American College of Obstetricians and Gynecologists.).