Prevalence of Microscopic Colitis in Patients with Normal or Nonspecific Colonoscopic Findings

: Background : Microscopic colitis (MC) is a chronic inflammatory bowel disease in the setting of normal appearing colonic mucosa and distinct histopathologic features . Microscopic colitis has two main subtypes, collagenous colitis (CC) and lymphocytic colitis (LC). Diagnosis of MC is mainly based on pathological examination of colonic biopsy. Aim : Estimation of MC among patients with normal or nonspecific colonoscopic findings. Methods : This cross-sectional study was conducted on (172) patients with normal or nonspecific colonoscopic findings. Full history taking, clinical examination, laboratory investigations, pelvi-abdominal ultrasound and complete colonoscopy examination were done. Endoscopic biopsies from the right and left side of the colon were taken for all patients for histopathological examination. Results : Of all the studied patients, 9 cases (5.2%) had MC with 6 patients (3.5%) having LC and 3 patients (1.8%) having CC. One hundred twenty-one cases were diagnosed as chronic nonspecific colitis (70.3%), 19 cases were diagnosed as chronic active colitis (11.1%) while 23 cases (13.3%) were normal. The median age of patients with MC was about 45 years and most of them were females. Univariate logistic regression analysis of predictors for developing MC showed that chronic diarrhea, chronic diarrhea duration and nonsteroidal anti-inflammatory drugs (NSAIDs) use are significant independent predictors for MC. Conclusion : MC could be considered in any patient with chronic lower gastrointestinal symptoms and apparently normal mucosa during colonoscopy examination. Multiple colonic biopsies should be taken from any patient with unexplained chronic lower gastrointestinal symptoms even with normal macroscopic picture to reach a definite diagnosis of MC.