Epidural analgesia and severe perineal laceration in a community-based obstetric practice.

Background: This study assessed whether epidural analgesia was an independent risk factor for severe perineal laceration.

Methods: A retrospective cohort study analyzed 2,759 patients at St. Francis Regional Medical Center who had vertex, spontaneous or induced, singleton, live, vaginal deliveries of neonates of at least 36 weeks' gestation. Patients with diabetes or severe cardiac disease were excluded. Outcomes measured were third- or fourth-degree perineal lacerations.

Results: Overall rate of severe perineal laceration was 6.38% (n = 176). Epidural analgesia was given to 634 (22.98%) women. Among women who had epidural analgesia, 10.25% (65 of 634) had severe perineal lacerations compared with 5.22% (111 of 2,125) of the women who did not have epidural analgesia. After controlling for major variables in a logistic regression analysis, epidural analgesia remained a significant predictor of severe perineal injury (odds ratio [OR] = 1.528, 95% confidence interval [CI] = 1.092-2.137). When instrument use was included in the model, epidural analgesia was no longer a statistically significant, independent predictor of severe perineal injury. (OR = 1.287, 95% CI = 0.907-1.826). Instrument use was found to be a strong predictor of severe laceration (OR = 3.245, 95% CI = 2.162-4.869). A logistic regression model examining predictors of instrument use found that epidural analgesia does significantly predict instrument use (OR = 3.01, 95% CI = 2.225-4.075).

Conclusion: Epidural analgesia is associated with an increase in severe perineal trauma as a result of an associated threefold increased risk of instrument use. Instrument use in vaginal delivery more than triples the risk of severe perineal laceration.