Differences in pathogenesis, incidence and outcome of perforation in inflammatory bowel disease

We have studied the patient records of 49 or 1,623 patients in whom perforation occurred during the course of inflammatory intestinal disease. Perforation occurred most commonly with toxic megacolon in UC, but without toxic megacolon in Crohn's disease of the colon. The incidence of perforation was significantly greater in UC than in Crohn's disease involving the colon. This was due primarily to the higher incidence of perforations with toxic megacolon in the former. The incidence of toxic megacolon was significantly greater in ulcerative colitis than in Crohn's disease involving the colon (CC and IC) and in UC than in ileocolitis. Although almost twice as frequent in UC than in Crohn's colitis alone, a significant difference could not be demonstrated in this series for patients with UC compared with CC. In UC, the incidence of perforation was 28 times as frequent if toxic colonic dilation occurred, compared with ten times the frequency of TCD in Crohn's disease involving the colon. There was a significantly higher incidence of perforation in patients with UC with toxic megacolon. The incidence of colonic perforation in the absence of toxic megacolon was similar in the two series (7 of 552 for UC, 1.2 per cent, versus 11 of 607 for CDC, 1.8 per cent). Mortality was no different in toxic megacolon in patients with UC compared with those with Crohn's disease or in patients with UC with free perforation compared with those with sealed perforation. Mortality was significantly greater in patients with perforation in UC than in those with Crohn's disease in the absence of toxic megacolon. All 15 patients with spontaneous free perforation in Crohn's disease treated by resection or exteriorization with diversion survived compared with four of seven deaths of free perforation in UC. We have no explanation for the remarkable difference in survival of free perforation in the absence of toxic megacolon in UC and CD, but it may be due to differing immunologic states or pathogenetic mechanisms.