Purpose: This study was designed to investigate the long-term consequences of anal sphincter defects detected after a first vaginal delivery.
Methods: A cohort of 197 primiparous females was evaluated for anal continence and anal sphincter defects in 1997. In June 2003 (6 years later), a postal questionnaire was sent to 74 females of this cohort, and answers from 54 (73 percent) were analyzed.
Results: In 1997, a transanal ultrasound found 66 anal sphincter defects (33.5 percent). Twenty-one females (10.6 percent) had persistent signs of anal incontinence 12 weeks after the index delivery. There was a significant correlation between the presence of anal sphincter defect and anal incontinence. Six years later, 11 of 54 females reported signs of anal incontinence: 50 percent of females with anal sphincter defect and only 8.1 percent of females without (P = 0.002). Large defects were more frequently associated with anal incontinence. Anal incontinence after the index vaginal delivery also was significantly associated with anal incontinence six years later. Multivariate analysis showed anal sphincter defect to be the only variable predictive of anal incontinence (odds ratio, 10.5; 95 percent confidence interval, 2.1-52.4).
Conclusions: Anal sphincter defects detected after the first vaginal delivery appear as the main risk factor for anal incontinence six years later.