Objective: To evaluate the prevalence of anal incontinence and anal sphincter defects after a first vaginal delivery and assess the effect of a second delivery.
Design: Prospective cohort study using postal questionnaires assessing incontinence to flatus and stools at three and thirty months postnatally and anal endosonography at three months following delivery.
Setting: Recruitment was from the antenatal clinic at the University Hospitals of Geneva, Switzerland.
Population: One hundred women with a vaginal delivery of their first child.
Main outcome measures: Prevalence of anal incontinence and anal sphincter defects.
Results: Anal incontinence was reported by 16/92 (17%) of women at three months after delivery and by 11/77 (14%) at 30 months. At that time, 5/54 (9%) with no further delivery reported incontinence, compared with 6/ 23 (26%) of those who had had another delivery (RR 2.8, 95% CI 1.0-8.3). Anal sphincter defects were diagnosed by endosonography in 46/87 (53%) women and were associated with reported incontinence at both three months (RR 1.9; 95% CI 1.4-2.6) and 30 months (RR 1.9: 95% CI 1.3-2.8) after delivery. The prevalence of anal incontinence at 30 months was highest (5/13, 39%) among those in whom a sphincter defect was diagnosed by endosonography after their first delivery and with a second delivery.
Conclusion: Anal incontinence after childbirth is associated with defects of the anal sphincter diagnosed by endosonography. Subsequent deliveries increase the risk of incontinence, particularly among women with a sphincter defect diagnosed after the first delivery.