Complete Obstetric Anal Sphincter Tear and Risk of Long-term Fecal Incontinence: A Cohort Study

BACKGROUND: Women with anal sphincter injuries have an increased risk of developing fecal incontinence despite surgical intervention. OBJECTIVE: The aim of this study was to evaluate the long-term risk of fecal incontinence after primary anal sphincter reconstruction and its impact on quality of life. DESIGN: This was a cohort study. SETTINGS: This study was performed at Aarhus University Hospital. PATIENTS: Women with complete anal sphincter rupture (exposed) from 1976 to 1991 and a control group of parous women (nonexposed) were included. MAIN OUTCOME: The primary outcomes measured were fecal incontinence, Wexner score, St Mark incontinence score, and quality of life. RESULTS: A total of 363 women were included (125 exposed and 238 nonexposed). The mean age was 50.4 years (95%CI: 49.8-51.0), with 22.2 years (95% CI: 21.7-22.6) of follow-up. At the time of follow-up, 49% of exposed women and 74% of nonexposed women were continent. Complete anal sphincter tear increases the risk of fecal incontinence twofold (relative risk = 2.00; 95%CI: 1.52-2.63). No other risk factors were identified. The mean Wexner score was 1.7 (95%CI: 1.3-2.1) vs 1.1 (95%CI: 0.7-1.4) (p = 0.02), and the mean St Mark score was 2.8 (95% CI: 2.1-3.4) vs 1.4 (95%CI: 1.0-1.9) (p < 0.001) in the exposed and nonexposed groups. Severity of fecal incontinence had a significant impact on the quality of life independent of exposure. LIMITATION: The cohort is relatively young; a short postmenopausal period limits the assessment of hormonal status and the effect of postmenopausal hormone replacement therapy. CONCLUSION: Complete obstetric anal sphincter tear increases the long-term risk of fecal incontinence twofold. When present, the severity of the incontinence symptoms is minor and the risk of incontinence for solid stool is not increased in comparison with the general population. Anal sphincter rupture is the only independent risk factor for fecal incontinence. The severity of fecal incontinence had the same impact on quality of life in both groups.