PROJECT PREVENT: a randomized controlled trial of preoperative vaginal metronidazole to decrease patient issues and infections after hysterectomy

Objectives: To evaluate if vaginal metronidazole for 5 days before hysterectomy decreases postoperative infections and patient issues.

Design: This randomized trial compared vaginal metronidazole for 5 days before a scheduled hysterectomy to no intervention. Sample size calculation was based on a 20% difference in issues and infection (30% incidence and 10% in the intervention arm) with 80% power and an alpha error of 0.05 and indicated 62 subjects needed in each arm.

Setting: Outpatient gynecology clinics at a single academic institution.

Participants: 154 subjects were screened for eligibility between July 2020 and September 2022. 133 underwent hysterectomy including 68 subjects (51.1%) randomized to the metronidazole and 65 (48.9%) controls. Overall, the population was racially and ethnically diverse. There was no significant difference in characteristics between the two groups.

Interventions: Vaginal metronidazole for 5 days before hysterectomy.

Main outcome measures: Postoperative patient issues and documented postoperative infections at 4-8 weeks after surgery.

Results: There was no difference in the composite rate of patient-reported issues and/or documented postoperative infection (53/133 (39.8%) with no difference between groups (29/68 (42.6%) vs 24/65 (36.9%), p=0.50). There was no difference in patient-reported issues which was 51/133 (38.3%) with no difference between groups (28/68 (41.2%) vs 23/65 (33.8%), p=0.49) or in documented infections with a rate of 25/133 (18.8%) with no significant difference between groups (15/68 (22.0%) vs 10/65 (15.4%), p=0.33). In the intervention arm, the compliance rate was 73.5% for all 5 days of vaginal metronidazole, and a per-protocol analysis was performed which resulted in no significant difference between groups.

Conclusions: There is insufficient evidence to suggest a significant benefit of preoperative vaginal metronidazole to prevent surgical site infections and postoperative patient issues in patients undergoing hysterectomy.

Trial registration number: ClinicalTrials.gov, NCT04478617.