How useful is colonoscopy in locating colorectal lesions?

Background: It is important to establish the precise location of a colorectal lesion preoperatively. We used a model based on colorectal cancer to assess the efficacy of colonoscopy in locating these lesions. Methods: We retrospectively analyzed all consecutive new colorectal cancer cases at the Department of Surgery, United Christian Hospital, Kong Kong, in 1995. Results: Of the 123 cases reviewed by us, 84 cases satisfied the analysis criteria. The overall accuracy was 81%. It was especially high in the rectosigmoid region (93%) and descending colon (100%). The overall predictive power was 83%. Tt was especially high in the right-sided colon (100%) and the rectosigmoid region (93%). Conclusions: We conclude that colonoscopy is an accurate means for locating lesions in the upper rectum and sigmoid colon. It is also very predictive of lesions in the upper rectum, sigmoid colon, and right-sided colon.