Mechanisms of rectal continence. Lessons from the ileoanal procedure.

To clarify mechanisms of rectal continence, we evaluated 34 patients who had straight or J-pouch ileoanal anastomosis. This evaluation included pressures, anal inhibitory reflex, neorectal capacity, neorectal compliance, and the ability to discriminate stool from gas. Both groups of patients had satisfactory anal sphincter resting pressures and neorectal capacities, and all could discriminate stool from gas despite the absence of any rectal mucosa. We conclude that normal rectal mucosa is not necessary to be able to discriminate stool from gas; a long rectal muscular cuff is not necessary for rectal sensation; essentially normal sphincter function is preserved, and this procedure does not normally fail because of inadequate sphincter function or the absence of the anal inhibitory reflex; and in the presence of normal sphincter function, continence is not dependent on the presence of normal mucosa or the anal inhibitory reflex but correlates with reservoir capacity and compliance as well as with the frequency and strength of intrinsic bowel contractions.