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.