Survey of anal sphincter dysfunction using anal manometry in patients with fecal incontinence: a possible guide to therapy

BACKGROUND Despite the surge of new medical and surgical approaches to treat fecal incontinence, the types of sphincter abnormalities in patients with incontinence have not been well characterized. We aimed to categorize anal sphincter dysfunction using anorectal manometry in patients with fecal incontinence as a potential guide for improved treatment. METHODS A retrospective review of 162 consecutive patients with fecal incontinence referred for anorectal manometry was performed. Resting anal pressure and maximal squeeze pressure were considered as measures of internal anal sphincter and external anal sphincter function respectively. RESULTS Mean age of the patients was 63 years (13-89); females (81.5%) and males (18.5%). 74% of the patients had sphincter dysfunction on anorectal manometry. Internal anal sphincter dysfunction was present in 62% patients vs. external anal sphincter dysfunction present in 44% patients. 80% females had abnormal manometry vs. 44% in males (P<0.0001). Internal anal sphincter dysfunction was present in 68% females vs. 37% in males (P=0.0026). CONCLUSIONS Overall, abnormal anorectal manometry studies revealed that internal anal sphincter dysfunction is the most common finding, alone or in combination with external anal sphincter dysfunction. We suggest that anorectal manometry may be important to delineate anal sphincter function prior to using newer therapeutic mechanical devices. Future studies using pharmacological agents to increase internal anal sphincter tone may be of clinical importance. Finally, the classification of fecal incontinence based on the type of sphincter dysfunction may be an improved guide in the selection of newer agents in treating fecal incontinence.