Cohort study of maternal and neonatal morbidity in relation to use of episiotomy at instrumental vaginal delivery

Objective: The aim of this study was to investigate the maternal and neonatal morbidity related to use of episiotomy for vacuum and forceps deliveries. Design: Retrospective population-based cohort study. Setting: Dundee, Scotland. Population: Two thousand one hundred and fifty three women who experienced an instrumental vaginal delivery between January 1998 and December 2002. Methods: Univariate and multivariate logistic regression analyses were performed comparing deliveries with and without the use of episiotomy. Main outcome measures: Extensive perineal tears (third and fourth degree) and shoulder dystocia. Results: Two hundred and forty-one (11%) of the 2153 women who underwent instrumental vaginal deliveries did not receive an episiotomy. Vacuum delivery was associated with less use of episiotomy compared with forceps (odds ratio 0.10,95% CI 0.07-0.14). Extensive perineal tears were more likely with use of episiotomy (7.5% vs 2.5%, adjusted OR 2.92, 95% CI 1.27-6.72) as was neonatal trauma (6.0% vs 1.7%, adjusted OR 2.62, 95% CI 1.05-6.54). Use of episiotomy did not reduce the risk of shoulder dystocia (6.9% vs 4.6%, adjusted OR 1.43, 95% CI 0.74-2.76). The findings were similar for delivery by vacuum and forceps. Conclusion: The use of episiotomy increased the risk of extensive perineal tears without a reduction in the risk of shoulder dystocia.