&NA;Ileosigmoid fistulas are found in Crohn's disease and may present a surgical dilemma.PURPOSE:This study was designed to examine surgical practice to determine types of intervention, enumerate complications, and elicit guidelines for surgical management.METHOD:The medical records of patients with ileosigmoid fistula and Crohn's disease from 1975 to 1995 were reviewed.RESULTS:Ninety patients (44 men) were studied. A preoperative diagnosis of ileosigmoid fistula was made in 77 percent of patients. Sigmoidrepairwas performed in 43 patients (47.8 percent), sigmoidresectionin 32 patients (35.6 percent), 12 patients (13.3 percent) underwent more extensive procedures, and 3 patients (3.3 percent) either had surgery elsewhere or were observed. The fistula was never directly responsible for a stoma. Therepairandresectiongroups were similar with respect to age, length of Crohn's disease, and preoperative symptoms. There was no significant difference between groups in the incidence of postoperative complications; there were no postoperative deaths. Average length of stay was 8.3 days following repair and 9.9 days after resection. Reasons for resection included significant purulence or inflammation, a large fistula defect, a defect on the mesenteric border of the sigmoid, and active sigmoid Crohn's disease. Surgeon's assessment of the presence of Crohn's disease in the sigmoid correlated with pathologic examination and was aided by knowledge of recent endoscopic appearance and biopsy results; intraoperative frozen section and colonoscopy were helpful in distinguishing serosal inflammation from active Crohn's disease.CONCLUSION:Contrast studies identified 77 percent of ileosigmoid fistulas preoperatively. Performing repair rather than resection does not increase the risk of complications, if standard surgical principles are followed. Preoperative or intraoperative endoscopy assists the surgical evaluation of the sigmoid.