Proctocolectomy with ileal pouch-anal anastomosis increases the frequency of stooling, perhaps due in part to the loss of an ileocecal or colonic braking effect on gastrointestinal transit. To assess whether colectomy with ileal pouch-anal anastomosis (IPAA) or with ileostomy accelerates gastrointestinal transit, we studied 16 IPAA patients (mean +/- SEM stool frequency, 8 +/- 1 stools/day), 5 patients after colectomy and Brooke ileostomy, and 8 healthy, unoperated controls (1 +/- 1 stools/day). Gastric emptying of liquids and small bowel transit of chyme were measured concurrently with a dual isotope technique. Gastric emptying was similar among all groups. In contrast, postprandial small bowel transit of the head of a duodenal marker was slowed, not accelerated, in IPAA patients (178 +/- 26 min) compared to Brooke subjects (80 +/- 32 min, P less than 0.05) and controls (75 +/- 15 min, P less than 0.01). Maximal filling of both the ileal pouch (341 +/- 19 min) and the ileostomy bag (348 +/- 12 min) occurred later than filling of the colon in controls (243 +/- 32 min, P less than 0.01). Overall stool frequency did not correlate with small bowel transit in the ileoanal patients, but the two ileoanal subjects with greatest stool frequency (11 and 18 stools/day) had the earliest arrival of marker at the pouch. In conclusion, removal of the colon markedly slowed small bowel transit in most patients, although it did not alter gastric emptying of liquids. Creation of an ileal pouch and ileoanal anastomosis further slowed transit of the head of the meal.(ABSTRACT TRUNCATED AT 250 WORDS)