Motor determinants of incontinence after ileal pouch-anal anastomosis.

Anal canal pressure gradient and ileal pouch motor activity were studied in continent and incontinent patients after ileal pouch-anal anastomosis. A multichannel microtransducer catheter was positioned in eight continent and eight incontinent patients 15 months or more after operation and 24-h ambulatory motor activity recorded. Resting anal pressures were significantly lower for incontinent patients during the day and night. The frequency of high-pressure waves was identical in both groups, but peak pressures were higher for incontinent patients. For continent patients, each high-pressure wave was accompanied by a rapid increase in anal canal pressure such that pressure in the pouch was always less than that in the anal canal. For incontinent patients this response was often absent. Incontinent patients had lower resting pressure, more prolonged anal canal relaxation, higher amplitude high-pressure waves and a non-responsive anal canal; the anal canal pressure gradient was therefore frequently reversed.