Pre-operative or postoperative colonic examination for synchronous lesions in colorectal cancer.

A review of 130 consecutive large bowel examinations at which a cancer of the colon or rectum was diagnosed has been undertaken. Of 50 patients examined by colonoscopy, the whole colon was seen in only 21 (42 per cent) and almost half of these had a tumour in the caecum or ascending colon. In most cases, an incomplete examination was the result of narrowing of the lumen by the tumour preventing passage of the endoscope. Of 80 patients examined by double contrast barium enema, the entire length of the colon was visualized in 83 per cent but the quality of the examination was sufficient to confidently exclude synchronous neoplastic lesions in only 51 per cent. The incidence of synchronous cancer in this series was within the expected range, although two such cancers were not detected until laparotomy, but the incidence of synchronous adenomas was two-thirds of the expected number in colonoscopy patients and one-third in those examined by barium enema. It is concluded that, in patients with known colorectal cancer, preoperative investigation is unreliable for the detection of all synchronous neoplasia and that patients should have postoperative colonoscopy.