The significance of diminutive colonic polyps found at flexible sigmoidoscopy.

In order to determine the importance of identification and follow-up of diminutive colonic polyps (DCPs) (i.e., those less than or equal to 5 mm in diameter), we studied 3006 patients undergoing flexible sigmoidoscopy. DCPs were found in 315 patients (10.5%). Biopsy of these lesions showed them to be nonneoplastic in 187 patients (59.4%) and neoplastic in 128 (40.6%). Overall, 35% of all DCPs found were neoplastic. Gross appearance of the lesions was found to be an unreliable means of predicting their histologic makeup. Of the 128 patients with neoplastic DCPs, 73 underwent further examination with barium enema and colonoscopy. Synchronous lesions were found in 57.5%. In 10 patients, synchronous lesions were of significance, including carcinomas, adenomas greater than or equal to 8 mm in diameter, or severely dysplastic adenomas. We conclude that all DCPs discovered at sigmoidoscopy should be biopsied and in patients in whom DCPs are found to be neoplastic, colonoscopy should be undertaken to search for proximal synchronous lesions.