Selected use of midline episiotomy: effect on perineal trauma.

A prospective, nonrandomized controlled study was performed to determine the effect of using midline episiotomy only for mothers who experienced fetal distress and/or operative vaginal delivery. Such a policy resulted in a significant decline in third- and fourth-degree lacerations in nulliparous women. This reduction was most pronounced in nulliparous women delivering infants larger than 3400 g. No third- or fourth-degree laceration occurred without antecedent episiotomy in any woman. A policy of using episiotomy selectively appears to lower the incidence of perineal trauma.