Risk of repetition of a severe perineal laceration.

OBJECTIVE: To compare the outcome of subsequent delivery in women with a history of a third- or fourth-degree laceration with outcomes in women without such a history.

METHODS: This retrospective study used a perinatal database and chart review from 1978 to 1995. Only women whose first delivery was at our institution at more than 36 weeks' gestation, vaginal singleton, vertex presentation, and birth weight greater than 2500 g, with a subsequent delivery were included. The women were grouped by presence or absence of a third- or fourth-degree (severe) perineal laceration in their first delivery. The subsequent delivery was analyzed for maternal age, weight, birth weight, gestational age, method of delivery, use of episiotomy, and occurrence of a severe laceration. Comparison of data was by Fisher exact and t tests.

RESULTS: Four thousand fifteen women met our starting criteria. In their first delivery, the average birth weight, use of instrumentation, and episiotomy rate were significantly higher in those women sustaining a severe laceration. When compared with women without a history of severe perineal laceration, women with such a history were at more than twice the risk for another in their subsequent delivery. The women at highest risk (21.4%) were those sustaining a laceration in their first delivery who underwent instrumental vaginal delivery with episiotomy in their subsequent delivery. When episiotomy or instrumental delivery was performed in the second vaginal birth, 52 (11.6%) of 449 women with a history of a severe perineal laceration sustained another, compared with 98 (6.5%) of 1509 without such a history (P < .001, odds ratio 1.9, 95% confidence interval 1.3, 2.7).

CONCLUSION: Women delivering their second baby, and in whom episiotomy or instrumentation is used, are at increased risk of severe perineal laceration compared with women delivery spontaneously.