Is severe perineal damage increased in women with prior anal sphincter injury?

There is conflicting data in the literature regarding the risk of obstetric anal sphincter laceration in patients with a prior laceration. This retrospective chart review seeks to examine the risk of recurrence of obstetric anal sphincter lacerations.

Patients who sustained anal sphincter laceration at delivery during a 13-year time period from January 1991 to December 2003 were identified from the medical records database at Temple University Hospital. All subsequent deliveries in this group of patients were extracted from the database. Chart review was performed on all subsequent deliveries with specific attention to demographic factors such as age, race, parity, etc., maternal weight, fetal weight, presence of maternal diabetes, and labor characteristics such as induction or augmentation of labor, instrumentation at delivery (vacuum or forceps), use of episiotomy, and degree of perineal laceration.

There were 23 451 vaginal deliveries at Temple University Hospital between January 1, 1991 and December 31, 2003. Anal sphincter laceration was noted in 778 subjects. Subsequent deliveries among the group of patients with prior sphincter tears numbered 271. Six (2.4%) patients had recurrence of anal sphincter lacerations, and five of them were third degree lacerations. The rate of recurrent lacerations was not significantly different from the rate of initial lacerations (2.4% vs. 3.3%; odds ratio 0.72, 95% confidence interval 0.33-1.59; p = 0.4). Women who sustained recurrent lacerations were older, more obese (mean weight 92 kg vs. 82 kg), had larger babies (3506 g vs. 3227 g), and were more likely to have episiotomies (66.7% vs. 7%) or instrumental deliveries (33.3 vs. 6.5%).

Prior anal sphincter laceration does not result in an increased rate of recurrence. Operative vaginal delivery particularly with episiotomy is a risk factor for both initial and recurrent laceration.