Approximately one half of women who sustain severe perineal laceration during vaginal delivery report significant long-term symptoms such as pain, dyspareunia and flatal incontinence. In addition, they are believed to be at high risk of repeated laceration during subsequent deliveries, but this risk has not been quantified. Peleg and colleagues studied the implications for a subsequent vaginal delivery in women with a history of severe perineal laceration during vaginal delivery.

The authors studied the records of 4,015 women who had delivered their first infant at a university hospital between 1978 and 1995 and had records of vaginal, vertex delivery of a singleton infant weighing 2,500 g (5 lb, 8 oz) or more after at least 36 weeks of gestation. The women were divided into two groups depending on evidence of perineal laceration (third or fourth degree). Records of a subsequent delivery at the same institution were analyzed for evidence of perineal laceration.

A total of 774 (19.3 percent) of the deliveries studied were complicated by severe perineal laceration. Factors significantly associated with perineal laceration were increased birth weight, use of instrumentation and episiotomy. Maternal age and weight were not significantly associated with laceration. During subsequent births, 58 (7.5 percent) of the women with previous laceration had repeated severe laceration. This was more than twice the risk of severe laceration than the risk in other women during second deliveries. The risk was clearly related to the use of episiotomy and instrumental delivery. The highest risk during the second delivery was in women with a history of severe laceration who had instrumental delivery and episiotomy in the second delivery. Over 20 percent of these women sustained a second severe laceration.

The authors conclude that cutting an episiotomy and using instruments during delivery are significantly related to severe perineal lacerations and that the risk of laceration is more than doubled in women with a history of severe perineal laceration during a previous delivery. After reviewing other studies, the authors call for a reassessment of episiotomy in modern obstetrics because the evidence linking this common procedure to severe laceration and subsequent morbidity is now overwhelming.