Contribution of gastrointestinal transit and pouch characteristics in determining pouch function

To determine the contributions of gastrointestinal transit and pouch characteristics to bowel frequency in patients with an ileoanal reservoir and no pouchitis.

Twenty one patients who had undergone restorative proctocolectomy, with ileostomy closure at least eight months previously, and who had no history of pouchitis were recruited. They were prospectively classified on the basis of their bowel frequency: 11 patients had good pouch function (bowel frequency less than six per day) and 10 had poor function (bowel frequency more than six per day). Gastrointestinal transit was studied using a dual isotope technique and anal and pouch physiological examination was performed on all patients.

Lag phase, 25% and 50% gastric emptying, small bowel transit time, and 10% and 50% pouch filling times, all for solids and liquids, were not significantly different between patients with good and poor function. Anal manometry and pouch and anal electrical sensitivity were also similar in the two groups. The volume of air and water required to elicit an initial sensation and the urge to defaecate were similar in both groups, but the maximum tolerated volume to both air (525 v 245 ml, good v poor function, median values) and water (625 v 370 ml) infusion was significantly (both p < 0.02) lower in patients with poor function.

Maximum tolerated volume in the pouch, which may reflect pouch size, sensitivity, compliance, or a combination of these is the major determinant of pouch function. Gastrointestinal transit does not seem to be an important determinant of function.