Abstract

Background
/Aims: Colonoscopy is the most effective method to detect and remove colonic polyps and for colorectal cancer screening and prevention. However, polyps are frequently missed during colonoscopy. The aim of this study was to determine the miss rates of polyps by colonoscopy and to evaluate the factors that affect the miss rates. Methods: Within sixty days after a first-time colonoscopy, consecutive polypectomies were performed in 317 patients who had one or more colon polyps. Results: The overall miss rate for polyps was 26.6%. As the withdrawal time increased, the number of polyps detected on the first colonoscopy decreased, and the miss rate decreased significantly (respectively p=0.000, p=0.028). The withdrawal time for an expert operator was shorter than the withdrawal time for a beginner operator (p=0.001). The miss rate for a beginner operator and expert operator was not different (p=0.271) due to interference with withdrawal time. The most frequent location of a polyp was the ascending colon and the most frequent size of a polyp was ≤5 mm. Conclusions: Although colonoscopy is the gold standard for colorectal polyp detection, it is imperfect even when meticulously performed. To reduce the miss rates of polyps, it is important that a careful examination with sufficient withdrawal time is performed, the colonoscopy is complete to the cecum, and that the bowel preparation is adequate. (Korean J Gastrointest Endosc 2008;36:132-137)

• Keywords: Colonoscopy, Miss rates, Colonic polyps, Screening test, Polypectomy