Does a second delivery increase the risk of anal incontinence?

Objective To evaluate the prevalence of anal incontinence and anal sphincte r defects after a first vaginal delivery and assess the effect of a second delivery. Design Prospective cohort study using postal questionnaires assessing incon tinence to flatus and stools at three and thirty months postnatally and ana l endosonography at three months following delivery. Setting Recruitment was from the antenatal clinic at the University Hospita ls 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 de fects. Results Anal incontinence was reported by 16/92 (17%) of women at three mon ths 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 sphinc ter 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 prevale nce of anal incontinence at 30 months was highest (5/13, 39%) among those i n 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 incr ease the risk of incontinence. particularly among women with a sphincter de fect diagnosed after the first delivery.