A randomized trial of the bactericidal effects of chlorhexidine vs. povidone iodine vaginal preparation

Abstract Background Precesarean vaginal preparation significantly reduces postpartum infections. While povidone iodine (PI) is the most commonly used vaginal antiseptic, evidence suggests that chlorhexidine gluconate (CHG) may be more effective. Objective We sought to compare the bactericidal effect of CHG and PI on vaginal bacterial colony counts in pregnancy. Study Design We conducted a prospective randomized controlled trial of vaginal preparation with 0.5% CHG vs. 10% PI vs. saline in women undergoing cesarean delivery at ≥ 34 weeks gestation. Women in labor or those with ruptured membranes, chorioamnionitis, abnormal placentation or allergy to study agents were excluded. Vaginal specimens were collectedly aseptically in the operating room immediately prior to and five to ten minutes after vaginal cleansing with three sterile sponge sticks. Our primary outcome was post-intervention aerobic and anaerobic bacterial colony counts, assessed by blinded investigators. Two-way ANOVA with simple-effects analysis and Tukey’s post test were used for multiple group comparisons. Secondary outcomes included baseline colony counts, change in colony counts, adverse events and maternal infections. Results Twenty-nine women consented and underwent vaginal preparation with CHG (n=10), PI (n=9), or saline (n=10). Groups were similar with respect to maternal age, BMI, race, ethnicity, parity, GBS status, and gestational age. There were no differences in the baseline colony counts. Vaginal preparation with PI resulted in lower aerobic and anaerobic colony counts compared to CHG and saline (p≤0.01 and p≤0.0001, respectively). PI eliminated over 99.9% of bacteria, while CHG and saline eliminated over 99% and 95%, respectively. While all agents decreased aerobic and anaerobic bacterial counts, 0.5% CHG was no more effective than saline in reducing anaerobic bacteria. There were no reported side effects or postpartum infections. Conclusions Compared to 0.5% CHG, 10% PI was more effective at reducing vaginal bacterial colony counts prior to cesarean delivery..