Risk of recurrence of anal sphincter lacerations

To estimate the rate of recurrence of anal sphincter lacerations in subsequent pregnancies and analyze the risk factors associated with recurrent lacerations

Data were obtained from the Pennsylvania Health Care Cost Containment Council, Division of In-Patient Statistics, regarding all cases of third- and fourth-degree perineal lacerations that occurred during a 2-year period (from January 1990 through December 1991). All subsequent pregnancies in this group of women over the next 10 years were identified, and the rate of recurrence of sphincter tears and risk factors for recurrence were analyzed.

The rate of anal sphincter lacerations was 7.31% (n = 18,888) during the first 2 years of study (1990-1991). In the next 10 years, these patients with prior lacerations were delivered of 16,152 pregnancies. Of these, 1,162 were by cesarean. Among the 14,990 subsequent vaginal deliveries, 864 (5.76%) had a recurrence of a third- or fourth-degree laceration. Women with prior fourth-degree lacerations had a much higher rate of recurrence than those with prior third-degree laceration (7.73% versus 4.69%). The rate for recurrent lacerations was significantly lower than the rate for initial lacerations (odds ratio 1.29, 95% confidence interval [CI] 1.2-1.4). Forceps delivery with episiotomy had the highest risk for recurrent laceration (17.7%, odds ratio 3.6, 95% CI 2.6-5.1), whereas vacuum use without episiotomy had the lowest risk (5.88%, odds ratio 1.0, 95% CI 0.6-1.7).

Prior anal sphincter laceration does not appear to be a significant risk factor for recurrence of laceration. Operative vaginal delivery, particularly with episiotomy, increases the risk of recurrent laceration as it does for initial laceration.

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