are biopsies necessary if colonoscopy is normal?
OBJECTIVE: We sought to determine the frequency of clinically important histological abnormalities in patients with chronic, unexplained diarrhea who had macroscopically normal colonic endoscopies. METHODS: Of 855 consecutive patients undergoing colonoscopy (595 cases) or flexible proctosigmoidoscopy (260 cases) by one endoscopist, biopsies were taken in 111 cases of unexplained diarrhea of at least 4-6 weeks duration in which the colorectal mucosa appeared grossly normal. All biopsies were blindly reviewed by one pathologist. RESULTS: In this group of patients with macroscopically normal colons, we identified no cases of Crohn’s disease or ulcerative colitis or any definite cases of collagenous colitis (CC) or lymphocytic colitis (LC). There was one case classified as “possible CC” and 13 cases classified as “some features of LC”. There were five cases of melanosis coli, one case of cytomegalovirus colitis (in an immunosuppressed patient), and one case of radiation injury. Ninety-one
