CHRONIC, UNEXPLAINED DIARRHEA - ARE BIOPSIES NECESSARY IF COLONOSCOPYIS NORMAL

Objective: We sought to determine the frequency of clinically importan t histological abnormalities in patients with chronic, unexplained dia rrhea who had macroscopically normal colonic endoscopies. Methods: Of 855 consecutive patients undergoing colonoscopy (595 cases) or flexibl e proctosigmoidoscopy (260 cases) by one endoscopist, biopsies were ta ken in 111 cases of unexplained diarrhea of at least 4-6 weeks duratio n in which the colorectal mucosa appeared grossly normal. All biopsies were blindly reviewed by one pathologist. Results: In this group of p atients with macroscopically normal colons, we identified no cases of Crohn's disease or ulcerative colitis or any definite cases of collage nous colitis (CC) or lymphocytic colitis (LC). There was one case clas sified as ''possible CC'' and 13 cases classified as ''some features o f LC.'' There were five cases of melanosis coli, one case of cytomegal ovirus colitis (in an immunosuppressed patient), and one case of radia tion injury. Ninety-one cases were classified as no pathological diagn osis or minimal histological change. Patients with abnormal histology were contacted to see if they had persistence or resolution of diarrhe a. For the cases of ''possible CC'' and ''some features of LC,'' diarr hea had resolved spontaneously in the majority. Interesting to note, o nly one of the five melanosis coli patients admitted to laxative use, raising the question of surreptitious abuse. Conclusions: We conclude that the yield of biopsies in diarrhea patients with macroscopically n ormal colons at endoscopy is low. It may be reasonable to obtain biops ies in patients with relatively severe or debilitating symptoms, with diarrhea that sounds ''organic'' (e.g., nocturnal stools, frequent wat ery stools, weight loss, elevated sedimentation rate), or in patients who are immunosuppressed. When biopsies are taken at colonoscopy, we s uggest taking about six from throughout the colon and placing them int o just one specimen container to help minimize costs.