Influence of the insertion time and number of polyps on miss rate in colonoscopy

OBJECTIVE: Colorectal polyps can be missed even during a meticulous colonoscopy by an experienced colonoscopist. The aim of this study was to investigate patient-, procedure-, and polyp-related factors affecting the miss rate of polyps on colonoscopy. MATERIAL AND METHODS: From March 2001 to February 2006, a total of 285 patients undergoing screening colonoscopy followed within 2 months by colonoscopy for polypectomy were enrolled. The main outcome measurements were factors associated with miss rates of polyp and the conditions for reducing missed polyps on colonoscopy. RESULTS: From the 285 colonoscopy pairs, a total of 1326 polyps were found. Overall, 350 of the 1326 polyps were missed (26.4%). Among those, 59 polyps (4.4%) were only seen on the first colonoscopy and 291 polyps (21.9%) were found only at the second colonoscopy. Patient-related factors were male sex (Odds Ratio (OR) 2.11, 95% Confidence Interval (CI) 1.21-3.70) and older age (OR 2.51, 95% CI 1.48-4.30). Procedure-related factors were colonoscopy by clinical fellows (OR 2.20, 95% CI 1.02-4.84) and delayed insertion time (OR 4.10, 95% CI 2.14-7.86). Polyp-related factors were more than four numbers of polyps (OR 4.48, 95% CI 1.91-10.5). However, a large polyp was less frequently missed on colonoscopy (OR 0.10, 95% CI 0.05-0.19). CONCLUSIONS: In usual clinical practice, colon polyps were frequently missed on colonoscopy. Comprehensive analysis of patient should be required to reduce the miss rates.ope