Adaptative changes in terminal ileum after total colectomy, mucosal proctectomy and straight ileo-anal anastomosis in chronic ulcerative colitis.

Total colectomy, mucosal proctectomy and straight ileo-anal anastomosis was performed in four adult patients with chronic ulcerative colitis (three males, one female; mean age 27.4 years). During a follow-up period of one to five years, all patients were continent, had spontaneous bowel evacuation (average 4-5 per day), and had normal bladder and sexual function. Sequential per rectal ileoscopies revealed loss of ileal folds and gradual transformation to a colonic type of mucosa. On barium studies, the anastomosed terminal ileum showed progressive ballooning and assumed a rectosigmoid appearance with complete disappearance of ileal characteristics. The histology showed a progressive transformation from ileal to colonic type of mucosa, with blunting and ultimate disappearance of villi, increasing goblet cell population, and increase in mononuclear cells in the lamina propria. Histochemical studies (high iron diamine and alcian blue stains) revealed a change from small intestinal to colonic mucin, progressing proximally from just above the anastomotic site. Two patients had a single recurrence with ileal histology resembling that of active ulcerative colitis; both responded to short term steroid therapy. The results of straight ileo-anal anastomosis compare well with Western reports of ileal reservoirs. Adaptative changes of 'colonisation' can be consistently demonstrated in the anastomosed ileum on follow-up; these start just above the anastomotic site and ascend proximally. The colonised ileum appears to be susceptible to the ulcerative disease.