Microscopic colitis not otherwise specified (NOS) in patients with diarrhoea predominant IBS in a tropical setting

Abstract

BACKGROUND: Coionoscopy is not recommended in IBS unless there are alarm symptoms. However, studies have shown that microscopic colitis and low grade inflammatory bowel disease (IBD) can mimic IBS. Microscopic colitis not otherwise specified (MNOS) is a distinct but poorly studied entity, especially in the tropics. OBJECTIVES: To investigate the presence of colonic and ileal inflammation in patients with diarrhea predominant IBS (IBS-D) in a tropicai setting. DESIGN, SETTING AND METHODS: In a prospective study over one year, we recruited 42 consecutive patients with IBS (diagnosed using Rome II criteria) and no alarm symptoms (mean age 36.1 yrs, M:F=29:13) and 13 controls {mean age 42.3 yrs, M:F=5:8). Serial colonic and ileal biopsies were obtained. RESULTS: Coionoscopy was macroscopically normal in all cases and controls. 23 (54.8%) cases had MNOS, 2(4.76%) ileal inflammation only, and 17(40.48%) had normal histology. Histology was normal in 11(84.62%) controls, and 2(15.38%) had MNOS. MNOS was significantly commoner in cases than controls (P=0.02, chi-square test). MNOS was commonest in the right side of the colon (n=20, 80%). 14(60.8%) patients with MNOS had a history suggestive of post infective IBS, compared to 7(36.8%) patients without MNOS (P>0.05). CONCLUSION: MNOS is common in patients with IBS-D in a tropical setting. Post infectious IBS seems commoner in patients with MNOS than those without MNOS, although this did not reach statistical significance. Coionoscopy with ileoscopy and serial biopsies are useful to detect mucosal inflammation in IBS-D.