The outcomes of midline versus medio-lateral episiotomy

Episiotomy is the surgical enlargement of the vaginal orifice by an incision of the perineum during the second stage of labor or just before delivery of the baby. During the 1970s, it was common to perform an episiotomy for almost all women having their first delivery, ostensibly for prevention of severe perineum tears and easier subsequent repair. However, there are no data available to indicate if an episiotomy should be midline or medio-lateral. We compared midline versus medio-lateral episiotomy for complication such as extended perineal tears, pain scores, wound infection rates and other complications.

We conducted a prospective cohort including 1,302 women, who gave birth vaginally between April 2005 and February 2006 at Srinagarind Hospital - a tertiary care center in Northeast Thailand. All women included had low risk pregnancies and delivered at term. The outcome measures included deep perineal tears (including perineal tears with anal sphincter and/or rectum tears), other complications, and women's satisfaction at 48 hours and 6-weeks postpartum.

In women with midline episiotomy, deep perineal tears occurred in 14.8%, which is statistically significantly higher compared to 7% in women who underwent a medio-lateral episiotomy (p-value < 0.05). There was no difference between the groups for other outcomes (such as blood loss, vaginal hematoma, infection, pain, dyspareunia, and women's satisfaction with the method). The risk factors for deep perineal tears were: midline episiotomy, primiparity, maternal height < 145 cm, fetal birth weight > 3,500 g and forceps extraction.

Midline compared to medio-lateral episiotomy resulted in more deep perineal tears. It is more likely deep perineal tears would occur in cases with additional risk factors.