PROSPECTIVE-STUDY OF MORPHOLOGIC AND FUNCTIONAL-CHANGES WITH TIME IN THE MUCOSA OF THE ILEOANAL POUCH - FUNCTIONAL APPRAISAL USING TRANSMUCOSAL POTENTIAL DIFFERENCES

This study was undertaken to investigate the morphologic and functiona l changes with time in the mucosa of the ileoanal pouch. METHODS: A mo rphologic study by histopathologic analysis, mucosal morphometry, and mucin histochemistry and a functional study by analysis of transmucosa l potential difference were performed in 27 patients with an ileoanal J-pouch after restorative proctocolectomy for ulcerative colitis. In 1 9 patients with a normal ileoanal pouch. two prospective follow-up ana lyses were performed after median functional pouch times of 14 and 39 months. We also evaluated eight patients with the diagnosis of pouchit is (median follow-up, 52.5 months). RESULTS: Tn the normal ileoanal po uch group, some degree of chronic and acute inflammatory; infiltration was identified in 100 percent and 63.2 percent of cases, respectively , with no significant differences being observed between the two follo w-up analyses. The mean villous atrophy index at the first and second follow-up was 0.54 and 0.52, respectively significantly lower (P < 0.0 01; an indication of a greater degree of villous atrophy) than the val ue obtained from the control group with a healthy terminal ileum (0.77 ). The group of patients with pouchitis exhibited statistically signif icant differences in the degree of acute and chronic inflammatory infi ltration, the extent of ulceration, the crypt depth, and the villous a trophy index, compared with patients without pouchitis. Tn the normal ileoanal pouch group, the: median percentage of sulfomucin with each d egree of atrophy (1 = mild; 2 = moderate: and 3 = severe) was 2.6, 4.5 , and 20.9 percent, respectively. In patients with pouchitis, the medi an percentage of sulfomucin was 5.9 percent. The mean transmucosal pot ential difference at the first follow-up (- 25.3 mV) was significantly lower (P = 0.001) than at the second (- 30.4 mV). Significant differe nces were apparent with respect to both the normal ileum (- 8.9 mV) an d the normal rectum (- 40.2 mV). CONCLUSION: These results suggest tl- lat the ileal pouch behaves as a neorectum, with different degrees of colonic metaplasia from a morphologic and a functional perspective.