Accuracy of colonoscopy in localisation of colorectal cancer.

An audit was performed of 77 patients with a single colorectal cancer visualised and sited before surgery by colonoscopic examination. The site of the cancer described at colonoscopy was compared with the actual site found at laparotomy. Six significant errors in preoperative localisation were encountered, when a change from the preoperatively planned resection to an alternative resection was found necessary. In two of these cases, extra morbidity was encountered as a result of these siting errors. Inaccurate localisation is a potential hazard of colonoscopy, especially when the examination is incomplete.