EVOLUTIONARY CHANGES IN THE PATHOLOGICAL DIAGNOSIS AFTER THE ILEOANALPOUCH PROCEDURE

PURPOSE: Inadequate initial differentiation between ulcerative colitis and Crohn's disease may lead to a diagnosis of indeterminate colitis. Construction of an ileoanal pouch in these patients may result in sig nificant morbidity and pouch failure when the ultimate diagnosis is Cr ohn's disease. METHOD: We prospectively studied 543 patients with idio pathic inflammatory bowel disease to determine whether a patient's pat hologic diagnosis changed with time and how it affected outcome. RESUL TS: Preoperative diagnosis was ulcerative colitis in 499 patients, ind eterminate colitis in 42 patients, and Crohn's disease in 2 patients. Prior colectomy was performed in 58 percent of patients with ulcerativ e colitis and in all patients with indeterminate colitis and Crohn's d isease. Postoperatively, the diagnosis changed in 20 patients with ulc erative colitis (13 to indeterminate colitis, 7 to Crohn's disease). A nother two patients with indeterminate colitis showed evidence of Croh n's disease in the resected rectal specimen. As patients were followed up, an additional 13 patients were found to have Crohn's disease (5 i ndeterminate colitis, 8 ulcerative colitis). With the current diagnosi s, perineal complications and pouch failure occurred, respectively, in 23 and in 2 percent of patients with ulcerative colitis, in 44 and in 12 percent of patients with indeterminate colitis, and in 63 and in 3 7 percent of patients with Crohn's disease. Pathologic diagnosis was a ltered in 35 patients 6 percent) overall, with a 12-fold increase in t he diagnosis of Crohn's disease. Only 3 percent of patients with ulcer ative colitis compared with 13 percent of patients with indeterminate colitis had a change in diagnosis to Crohn's disease (P = 0.006; Fishe r's exact test). CONCLUSION: Pouch-related complications, eventual pou ch failure, and discovery of underlying Crohn's disease occurred in a significant number of patients with a diagnosis of indeterminate colit is. Until more accurate diagnostic differentiation is available, cauti on is advised in recommending the ileoanal pouch procedure to patients with indeterminate colitis.