Sequential Crohn's Ileitis, Ileosigmoidal Fistula, Segmental Sigmoid Polyposis, and Sigmoid Stricture: The Natural History.

BACKGROUND: We have previously recognized segmental sigmoid polyps as an indicator of a fistula from Crohn's ileitis to the sigmoid or the proximal rectum. In the course of this study, we realized that many patients with this fistula had no sigmoid polyps, but the sigmoid was the site of marked inflammation and early or late stricture formation. Furthermore, in some patients with a stricture, the fistula was not recognized until the surgeon (or the pathologist) dissected an inflammatory peri-ileal and/or a perisigmoidal mass.In this study, we have sought to clarify the sequence of events by focusing on the segmental inflammation and the stricturing of the sigmoid so that its significance can be recognized as a local complication of the ileitis and the progression of its severity as opposed to arising sui generis.

MATERIALS AND METHODS: From our database of >3000 patients with inflammatory bowel disease at Lenox Hill Hospital, we identified 45 patients with Crohn's ileitis and ileosigmoid fistula (ISF): 24 had segmental sigmoid polyps and 18 had segmental inflammatory sigmoid strictures. The fistula was first seen by imaging in 36 patients, but not until resection by the surgeon or dissection by the pathologist in 7 patients.

RESULTS: The method of diagnosis for the initial recognition of the ISF and the sigmoid stricture is presented in Table 1. In 36 of the 45 cases, the ISF was recognized by radiologic imaging. In total, 31 of the 36 cases required surgical intervention, not because of the fistula, but because of small-bowel obstruction due to the ileitis. In 7 of the 31 (22%) cases, the fistula was recognized only by dissection of the inflammatory ileosigmoid mass by the surgeon or examination of the surgical specimen by the pathologist. The sequence of events from the originating ileitis to the ISF to the segmental sigmoid polyposis and stricture, with the resulting sigmoid obstruction, is shown in Figures 1A-E.

CONCLUSIONS: We emphasize the natural history of the ISF so that its recognition will lead to earlier medical management of the originating ileitis. Furthermore, it adds evidence of the recognition that the causative agent of Crohn's disease is carried by the fecal stream.