Diagnosis of anal sphincter tears by postpartum endosonography to predict fecal incontinence

Abstract

Objective: To determine whether anal endosonography immediately after vaginal delivery can predict subsequent fecal incontinence. Methods: We studied nulliparas who delivered vaginally and had no anal sphincter tears (third- or fourth-degree perineal tears) diagnosed clinically by endosonography before any suture of the perineum. The sonographer was unaware of delivery details and the obstetrician and the women were not informed of endosonography results. Therefore, the suture of the perineum and the outcomes were not influenced by sonographer’s diagnoses. Three months after delivery, we assessed fecal incontinence by self-administered questionnaires. Results: Clinically undetected tears of the anal sphincter were diagnosed by anal endosonography in 42 of 150 women (28%). The external anal sphincter alone was involved in 30 women (20%), the internal anal sphincter alone in two (1.3%), and both in ten (7%). The postal questionnaire was returned by 144 women. Incontinence was reported by 22 (15%, 95% confidence interval [CI] 10%, 22%), consisting mainly of incontinence to flatus only (16 of 22, 73%, 95% CI 50%, 89%). Clinically undetected anal sphincter tears diagnosed by endosonography were associated with incontinence 3 months after delivery (odds ratio [OR] 8.8; 95% CI 2.9, 26.5). The sensitivity of anal endosonography was 68% (95% CI 49%, 88%) and the positive predictive value 37% (95% CI 22%, 51%). Conclusion: Anal endosonography immediately after vaginal delivery allows diagnosis of clinically undetected anal sphincter tears that might be associated with subsequent fecal incontinence.