Prevalence of Microscopic Colitis in Diarrhea-predominant Irittable Bowel Syndrome Patients: Cohort Study From Upper Egypt.

Background and aim There is controversy about colonoscopy and taking biopsy from the normal colonic mucosa in patients with a clinical diagnosis of diarrhea-predominant irritable bowel syndrome (D-IBS). This study aims to estimate the prevalence of microscopic colitis (MC) in D-IBS patients and to select patients without the well-known alarming features who will benefit from colonoscopy and biopsies from the normal colonic mucosa. Patients and methods We performed a cohort cross-sectional study over 6 months duration in a total of 129 patients with Rome III criteria of D-IBS after excluding cases with features of organic diseases. Cases were subjected to colonoscopy and biopsies from the colonic mucosa that seemed normal. Results Histopathologic examination of biopsies taken from cases with normal colonic mucosa revealed 86 (71.66%) cases with nonspecific colitis, 26 (21.66%) cases with MC and 8 (6.66%) cases with ulcerative colitis. Concomitant immunologic diseases (P=0.00005) and triggering drugs intake (P=0.006) were significantly more common in the MC group. The mean duration of diarrhea in MC patients was significantly longer than that of nonspecific colitis and ulcerative colitis patients (P=0.0006). Conclusions Prevalence of MC in D-IBS patients from Upper Egypt is relatively high (21.66%). Concomitant immunologic diseases, possible triggering drugs intake, and long duration of diarrhea are significant risk factors for undiagnosed MC in D-IBS patients.