Perineal descent at defecography in women with straining at stool: a lack of specificity or predictive value for future anal incontinence?

OBJECTIVE: To determine (1) whether patients complaining of straining at stool have pelvic floor descent and anal abnormalities similar to those of patients with anal incontinence and (2) whether these patients are prone to develop anal incontinence. METHODS: To answer the first question we used defecography to study perineal floor position at rest, during maximal contraction of the anal sphincter and during straining, and we performed anorectal manometry in 46 women with straining at stool but without anal incontinence at the beginning of the study, and in 46 women with idiopathic anal incontinence, matched for age. To answer the second question, we performed a 5-year follow-up study to determine whether anal incontinence had developed in those women with straining at stool. RESULTS: Perineal floor position at rest, during maximal contraction of the sphincter and during straining, resting pressure in the upper part of the anal canal, maximal amplitude and duration of the voluntary contraction were similar in the 46 women with straining at stool and the 46 women with idiopathic anal incontinence. In the follow-up study, 24 of the 46 women with straining at stool were contacted. The incidence of anal incontinence after 5 years was higher among these 24 women than in a control group of 20 women (13 out of 24 versus three out of 20, for women with straining at stool versus controls respectively; P < 0.01). The 13 patients with straining at stool who became incontinent had, at the initial investigation, a lower maximal amplitude of voluntary contraction, greater perineal descent at rest and less elevation of the pelvic floor during maximal contraction of the anal sphincter than the other women (P < 0.05). CONCLUSION: Women with chronic straining at stool have perineal descent at rest and during straining similar to that of incontinent women. Women with chronic straining are also prone to develop anal incontinence, suggesting that perineal descent at defecography in women with straining at stool may predict future anal incontinence.