Faecal incontinence in patients with systemic sclerosis: is an impaired internal anal sphincter the only cause?

Objectives: Faecal incontinence affects 40% of patients with systemic sclerosis (SSc). Several factors, including impaired anal sphincter function, reduced rectoanal sensation, abnormal rectoanal wall properties, and fast gastrointestinal transit, can cause faecal incontinence. Internal anal sphincter function is reduced in some patients with SSc, but other factors causing faecal incontinence remain to be studied in detail. Our aim was to compare tests of colorectal and anal physiology in patients with SSc suffering from faecal incontinence to those of SSc patients without faecal incontinence and healthy controls. Methods: Twenty SSc patients [18 women, mean age 58 (range 38-79) years] with bowel dysfunction were examined using rectoanal physiology tests, impedance planimetry, radiographic assessment of gastrointestinal transit time, and the Wexner incontinence score questionnaire. The results from SSc patients with faecal incontinence (n = 8) were compared to those from patients without faecal incontinence (n = 12) and healthy subjects [rectoanal physiology tests: 24 women, mean age 72 (range 65-83) years; impedance planimetry: 20 women, mean age 51 (range 40-80) years]. Results: Anal resting pressure, which reflects internal anal sphincter function, was significantly reduced in SSc patients with faecal incontinence but not in those without. There were no significant differences in external anal sphincter function, rectoanal sensibility, rectal wall properties, or gastrointestinal transit time. Conclusion: The main cause of faecal incontinence in SSc is poor function of the internal anal sphincter smooth muscle.