DOES MIDLINE EPISIOTOMY INCREASE THE RISK OF 3RD-DEGREE AND 4TH-DEGREE LACERATIONS IN OPERATIVE VAGINAL DELIVERIES

Objective: To explore the association between midline episiotomy and t he risk of third- and fourth-degree lacerations during operative vagin al delivery with either vacuum extractor or forceps. Methods: This ret rospective cohort study analyzed all operative vaginal deliveries at a university hospital in 1989 and 1990. Univariate analysis of the rela tionships between perineal lacerations and obstetric variables was per formed. Stratified analysis using the relevant variables was used to c alculate relative risk (RR) estimates. Results: Episiotomy, birth weig ht, and whether the index birth was the first vaginal birth were assoc iated with third- and fourth-degree perineal lacerations. Stratified a nalysis demonstrated an RR of 2.4 with a 95% confidence interval of 1. 7-3.5 for rectal injury with episiotomy, adjusting for parity and birt h weight. Conclusion: Midline episiotomy is associated with an increas ed risk of third- and fourth-degree perineal lacerations in operative vaginal deliveries.