(378) Episiotomy in the US: have we got it right?

Objective: A recent randomized controlled trial (Bergendahl et al, BMJ June 2024) reported a 50% reduction in obstetric anal sphincter injury (OASI) in nulliparous patients undergoing vacuum delivery who were assigned to lateral episiotomy versus no episiotomy. Our objective was to evaluate OASI in a similar US population.

Study Design: This retrospective study included births at 17 US hospitals (2022-2023). The analysis was restricted to singleton nulliparous, pregnancies undergoing vacuum delivery at >= 34 weeks’ gestation. The outcome was 3rd or 4th degree laceration (OASI). The comparator groups were mediolateral episiotomy (ML) and midline episiotomy (M) and the reference group was no episiotomy (N). The incidence of OASI was compared among the ML, M, and N groups. Unadjusted odds ratios (OR) for OASI were calculated for each of ML and M groups compared to the N group. Adjusted ORs controlled for maternal age, BMI, and birthweight.

Results: Of 926 vacuum deliveries that met eligibility criteria, 775 (83.7%) were in the N, 80 (8.6%) in the M, and 71 (7.7%) in the ML episiotomy group. OASI was reported in 8.4% of the ML, 14.6% of the N, and 26.2% of the M episiotomy group (Table 1). Compared to the N group, the adjusted odds of OASI were significantly higher in the M group (2.25; 95% CI 1.28, 3.93) and lower in the ML group but the latter did not meet statistical significance (0.54; 95% CI 0.23, 1.30). Compared to ML, M episiotomy was associated with a significantly increased risk for OASI: adjusted OR 4.41 (95% CI; 1.55, 12.49).

Conclusion: Our study showed increased risk for OASI with midline episiotomy and a trend towards decreased OASI with mediolateral episiotomy, compared to no episiotomy in nulliparous patients undergoing vacuum delivery. Additionally, midline episiotomy was associated with a significantly increased risk for OASI compared to a mediolateral approach. Given this and the recent RCT results, reflection on episiotomy technique and more research into operative vaginal delivery are needed in the US.