Introduction
Anal incontinence is a source of distress for patients, with a major impact on sexual health 1 and quality of life2,3. It is a frequent symptom 4, with a prevalence 14.8% among women in a population-based study in the United States 5. Obstetrical anal sphincter injuries (OASIS) are visible third or fourth-degree perineal lacerations, reported in 2 to 12% of vaginal deliveries 6,7. Occult anal sphincter lesions, which are not noticed at the time of delivery, can be detected by systematic endoanal ultrasonography in up to 27% of women after their first vaginal delivery8. Anal sphincter lesions may result in anal incontinence in 9% of women7,8. Instrumental delivery is the most important risk factor for anal incontinence, with anal sphincter lesions reported in up to 63% to 82 % of forceps deliveries 8 and anal incontinence in 23 % 8. Post-delivery anal incontinence decreases over time, but it contributes to anal incontinence in the long term 9.
In case of anal sphincter lesions at the first delivery, cesarean section (CS) is often discussed for subsequent deliveries, with the purpose of protecting anal function. However, recommendations differ between countries and centers. 10 1112. Current ACOG guidelines state that women with a history of OASIS who are asymptomatic and without any evidence of sphincter compromise may be allowed to have a vaginal delivery, however it is reasonable to perform a cesarean delivery based on patient request13. To date there is no high-level evidence from a randomized trial to inform the decision13 . The potential benefit needs to be proven, since CS is a major surgical procedure with risks for the mother and infant 14, including maternal morbidities and mortality at the time of the surgery and during subsequent pregnancies15. In recent retrospective cohort studies comparing CS versus repeat VD in women with a history of anal sphincter lesions, no significant difference was found in the incidence of anal incontinence 9,16. However, the limitations were the potential indication bias inherent to observational studies and the retrospective design. The potential benefit of prophylactic CS on urinary incontinence, quality of life and sexual functions also must be addressed, as they deeply impact quality of life 2,17. Our main purpose was to evaluate whether anal incontinence could be prevented by planned CS for the second delivery, in women with asymptomatic anal sphincter disruption after the first delivery.