Chlorhexidine Versus Iodine for Vaginal Preparation Before Hysterectomy: A Randomized Clinical Trial.

OBJECTIVE The American College of Obstetricians and Gynecologists does not provide a recommendation regarding the preferred vaginal preparation solution. We intended to compare the effectiveness of chlorhexidine versus iodine in decreasing vaginal bacterial counts. METHODS In this institutional review board-approved study, participants undergoing total hysterectomy via vaginal or laparoscopic approach were randomized to 4% chlorhexidine or 10% iodine for presurgical vaginal preparation. Swabs were collected from the vaginal mucosa before, then 30, 60, and 90 minutes after preparation. Our primary outcome was the number of positive cultures (≥5,000 bacteria) at 90 minutes. The secondary outcomes included the presence of selected pathogens, postoperative complications, and infections. The sample size of 71 per arm was calculated using P = 0.05, 80% power, and anticipating a 22% difference in positive cultures. RESULTS Between May 2018 and August 2019, 85 participants were randomized. The average age was 59.8 years (SD, 11.4), and the median Charlson Comorbidity Index score was 2 (minimum, 0; maximum, 6). Baseline bacterial counts were similar in both groups. Chlorhexidine demonstrated a lower percentage of positive cultures at 90 minutes (47.6% vs 85.4%; odds ratio, 10.6; P = 0.001). In addition, the median bacterial count in the chlorhexidine group was significantly lower than the iodine group (3,000 vs 24,000 colony-forming units, P < 0.001) at 90 minutes. No surgical site infections were identified in either group during the 30-day postoperative period, and there were no reported adverse reactions to either solution. CONCLUSIONS Chlorhexidine resulted in substantially lower bacterial counts after preparation compared with iodine. Gynecologic surgeons may consider switching to 4% chlorhexidine for vaginal preparation before hysterectomy.