Conventional colonoscopy versus chromoendoscopy and magnifying endoscopy for the diagnosis of colorectal lesions: a comparative prospective study in 995 patients

Early endoscopic diagnosis of colorectal cancers is the best tool for the reduction of colorectal cancer mortality, but conventional colonoscopy seems unable to detect minor changes in the colorectal mucosa. The authors compare the results of conventional colonoscopy and chromoendoscopy plus magnifying endoscopy for the detection of colorectal lesions. This prospective study evaluated 995 consecutive selected patients. All patients with a previous diagnosis of colorectal polyps, inflammatory bowel disease, history of colorectal surgery, high coagulative risk or poor bowel preparation were excluded from the study. All examinations were performed by a single endoscopist. The authors compared the results of conventional endoscopy and chromoendoscopy with a 0.4% indigo carmine solution and magnifying endoscopy. At the end of each examination, data from ordinary and dye-spraying views were carefully recorded. A total of 202 protruding, 99 flat and 5 depressed lesions were detected. The incidence of high-grade dysplasia and early carcinoma was 9.9% for protruding lesions, 13.1% for flat lesions and 60% for depressed lesions. Chromoendoscopy revealed new neoplastic patterns not detectable at conventional endoscopy in 127 patients. This prospective study shows the high accuracy rate of chromoendoscopy for the detection of non-polypoid lesions. Chromoendoscopy could be used as a routine procedure in order to enhance the early diagnosis of colorectal cancers.