Segmental sigmoid polyposis as a colonoscopic indicator of an ileosigmoid fistula in Crohn's ileitis.

Background and aims: Ileosigmoid fistulas (ISFs) are frequently undiagnosed prior to surgery. This study was designed to describe a polyp or cluster of polyps limited to the sigmoid colon as a marker of ISF in patients with ileitis. This novel finding will increase a gastroenterologist’s opportunity to detect them preoperatively and their prognostic implication of worsening ileitis. Methods: The medical records of patients with Crohn’s disease and ISF were reviewed to determine whether colonoscopy had revealed polyposis limited to the sigmoid colon and its frequency. Results: Thirty-seven patients with Crohn’s ileitis complicated by ISF were identified from our database. Twenty had one or more sigmoid polyps without polyps elsewhere in the colon suggesting the site of fistula exit. Fifteen of the patients had ISF and five had ileorectal fistula (IRF). The fistula was detected by various means, including colonoscopy, sigmoidoscopy, small bowel X-ray series, barium enema, computed tomography, and magnetic resonance enterography. The ISF was generally diagnosed prior to the recognition and significance of the segmental polyps. These polyps were inflammatory or hyperplastic on pathologic review. Conclusion: Most ISFs and IRFs are now found preoperatively by imaging and some are incidental surgical findings. The segmental sigmoid polyps that we describe should help the gastroenterologist to be suspicious of ISF. The polyps are a surrogate marker for the progression of the fistula and the underlying ileitis as they tend to appear after the fistula has matured and lead to increased intensity of medical therapy well before surgical intervention is required.