The Yield of Colonoscopy in Patients With Non-Constipated Irritable Bowel Syndrome: Results From a Prospective, Controlled US Trial

OBJECTIVES: There are limited data on the yield of colonoscopy in patients with irritable bowel syndrome (IBS). This study compared the prevalence of structural colonic lesions in patients with suspected non-constipation-predominant IBS and healthy volunteers. We also determined the yield of rectosigmoid biopsies in patients with suspected IBS. METHODS: This was a prospective, case-control study conducted at three US sites. Patients with suspected non-constipation-predominant IBS (Rome II) underwent colonoscopy with rectosigmoid biopsies. Healthy persons undergoing colonoscopy for colorectal cancer screening or polyp surveillance comprised the control group. Abnormalities identified at colonoscopy were compared between suspected IBS and control groups. RESULTS: In all, 466 suspected IBS patients and 451 controls were enrolled. Suspected IBS patients were significantly younger (P < 0.0001) and more frequently female (P < 0.0001) than controls. The most common lesions in suspected IBS patients were hemorrhoids (18.2%), polyps (14.6%), and diverticulosis (8.8%). Suspected IBS patients had a lower prevalence of adenomas (7.7% vs. 26.1%, P < 0.0001) and diverticulosis (8.8% vs. 21.3%, P < 0.0001) and higher prevalence of mucosal erythema or ulceration (4.9% vs. 1.8%, P < 0.01) compared with controls. Logistic regression found the between-group differences in adenoma prevalence to be robust after correction for demographic factors. The overall prevalence of microscopic colitis in suspected IBS patients was 1.5% (7/466) and 2.3% (4/171) in those >= 45 years of age. CONCLUSIONS: The prevalence of structural abnormalities of the colon is no higher in suspected non-constipation IBS patients than in healthy controls. Microscopic colitis can be identified in a small proportion of persons with IBS symptoms.