Original articleClinical endoscopyAdequacy of flexible sigmoidoscopy with biopsy for diarrhea in patients under age 50 without features of proximal disease

BackgroundThe optimal endoscopic investigation of diarrhea in patients under age 50 without specific features of right-sided colonic/ileal disease is inadequately defined.ObjectiveTo assess the potential additional yield of colonoscopy over flexible sigmoidoscopy (FS) in this group.DesignRetrospective cohort study.SettingTwo teaching hospital endoscopy units.PatientsThis study involved all patients under age 50 who had a colonoscopy between 1997 and 2007 to investigate diarrhea, without high-risk features of right-sided colonic/ileal disease, inflammatory bowel disease (IBD), or rectal bleeding.InterventionColonoscopy and biopsy.Main Outcome MeasurementsDiagnostic yield of colonoscopy over FS with biopsy.ResultsColonoscopic appearances were abnormal in 126 of 625 eligible patients (20%); 72% of abnormalities were within reach of FS. The most common endoscopic abnormality was suspected inflammation in 60 patients (10% overall), reportedly confined to the proximal colon or ileum in 22 patients (37% of this group). Histology from areas of suspected inflammation revealed features of IBD in 68% of patients, but results were normal in the remainder. In the 22 patients with suspected isolated proximal disease, 8 patients (36%) had normal histology results, and a further 6 had left-side colon biopsies demonstrating IBD. In patients with macroscopically normal colons, histological evidence of IBD or microscopic colitis occurred in 14 and 12 patients, respectively, with changes in the left side of the colon in 93% of patients. In this patient group, 85% of IBD or microscopic colitis could have been detected by FS and biopsy. The negative predictive value of FS with biopsy was 98% for IBD and 99% for microscopic colitis.LimitationsRetrospective study.ConclusionFS is adequate for the investigation of diarrhea in patients under age 50 who lack other features, but its yield depends on biopsy of the left side of the colon.