Abstract
BACKGROUND AND AIMS: Most colonoscopy examinations in patients with chronic unexplained diarrhea do not reveal endoscopic abnormalities, and routine random colon biopsy specimens are taken for further diagnostic assessment. In this study, we aimed to perform a systematic review and meta-analysis to study the pooled diagnostic value of random colon biopsy sampling in this patient population. METHODS: Multiple databases (MEDLINE, Scopus, Embase) were searched in May 2022 for studies evaluating the diagnostic yield of random biopsy sampling in patients with chronic diarrhea with normal colonoscopy examinations. Standard meta-analysis methods used the random-effects model, and heterogeneity was assessed using the I (2) statistics. RESULTS: Twenty-one studies were included in the study (3322 patients). The pooled rate of normal colon biopsy sampling was 48% (95% confidence interval [CI], 31-65.2; I (2) = 98%), and normal ileal biopsy sampling was 88.5% (95% CI, 51.3-98.3; I (2) = 93%). The pooled rate of significant histopathologic change was 30% (95% CI, 20-41; I (2) = 96%). The pooled rates of specific diagnoses based on random colon biopsy sampling were as follows: microscopic colitis, 15% (95% CI, 10-21; I (2) = 92%); lymphocytic colitis, 9% (95% CI, 6 -13; I (2) = 85%); collagenous colitis, 3.5% (95% CI, 2.4-5.7; I (2) = 80%); nonspecific colitis, 20% (95% CI, 11-32.8; I (2) = 97%); inflammatory bowel disease, 1.7% (95% CI, .8-3.5; I (2) = 54%); and eosinophilic colitis, 2.3% (95% CI, 1.1-4.5; I (2) = 69%). CONCLUSIONS: This meta-analysis of 21 studies demonstrated significant histopathologic change in 30% and microscopic colitis in 15%. Normal colon biopsy sampling was noted in 48% and normal ileum biopsy sampling in 88.5%. Ileal biopsy data were based on limited data and studies (only 3 included). In studies with a mean patient age <49 years, 40% demonstrated significant histopathologic changes.