BACKGROUND: Primiparous women have an increased risk of obstetric anal sphincter injury; because most of these patients deliver again, there are major concerns about mode of delivery: the risk of recurrent obstetric anal sphincter injury and the risk of long-term symptoms of anal incontinence. Although an elective cesarean delivery protects against recurrent obstetric anal sphincter injury, it is uncertain how the second delivery affects the risk of long-term anal incontinence.

OBJECTIVE: The purpose of this study was to evaluate whether the mode of delivery for a second pregnancy, after a documented obstetric anal sphincter injury at the time of first delivery, had a significant impact on the prevalence of anal and fecal incontinence in the long term.

STUDY DESIGN: We performed a population-based questionnaire cohort study that evaluated anal and fecal incontinence, fecal urgency, and affected quality of life caused by anal incontinence in 1978 patients who had obstetric anal sphincter injury in the first delivery and a second vaginal (n = 1472 women; 71.9%) or elective cesarean delivery (n = 506 women; 24.7%) delivery. We performed uni- and multivariable logistic regression analyses to compare groups.

RESULTS: Long-term anal incontinence was reported in 38.9% of patients (n = 573) with second vaginal compared with 53.2% (n = 269) with elective cesarean delivery. The corresponding numbers that reported anal incontinence before the second pregnancy was 29.4% for those with vaginal delivery compared with 56.2% of those with elective cesarean delivery (ie, there was a significantly larger change in the risk of anal incontinence in the group with a second vaginal delivery compared with the change in the group with elective cesarean in second delivery). However, adjusted for important maternal and obstetric characteristics, the risk of long-term anal incontinence was nonsignificantly lower in patients with elective cesarean delivery (adjusted odds ratio, 0.77; 95% confidence interval, 0.57-1.05; P = .09). Furthermore, the risk of fecal incontinence was not affected by mode of delivery in the multivariable analysis (adjusted odds ratio, 1.04; 95% confidence interval, 0.76-1.43; P = .79). Patients with persistent anal incontinence before the second pregnancy (n = 496) had an increased risk of long-term anal incontinence (adjusted odds ratio, 64.70; 95% confidence interval, 42.85-97.68; P < .001) and long-term fecal incontinence (adjusted odds ratio, 13.76, 95% confidence interval, 10.03-18.88, P<0.001) compared with patients without anal incontinence before the second pregnancy.

CONCLUSION: Mode of second delivery did not significantly affect the risk of long-term anal or fecal incontinence in multivariable analyses of patients with previous obstetric anal sphincter injury in this population in which patients with anal incontinence before the second pregnancy were recommended to have an elective cesarean delivery in the subsequent delivery. Nonetheless, we found that patients with vaginal delivery had a higher risk of deterioration of anal incontinence symptoms compared with those with an elective cesarean delivery.