Miss rate of colorectal neoplastic polyps and risk factors for missed polyps in consecutive colonoscopies

Colonoscopic polypectomy is the best diagnostic and therapeutic tool to detect and prevent colorectal neoplasms. However, previous studies have reported that 17% to 28% of colorectal polyps are missed during colonoscopy. We investigated the miss rate of neoplastic polyps and the factors associated with missed polyps from quality-adjusted consecutive colonoscopies. We reviewed the medical records of patients who were found to have colorectal polyps at a medical examination center of the Kangbuk Samsung Hospital between March 2012 and February 2013. Patients who were referred to a single tertiary academic medical center and underwent colonoscopic polypectomy on the same day were enrolled in our study. The odds ratios (ORs) associated with polyp-related and patient-related factors were evaluated using logistic regression analyses. A total of 463 patients and 1,294 neoplastic polyps were analyzed. The miss rates for adenomas, advanced adenomas, and carcinomas were 24.1% (312/1,294), 1.2% (15/1,294), and 0% (0/1,294), respectively. Flat/sessile-shaped adenomas (adjusted OR, 3.62; 95% confidence interval [CI], 2.40-5.46) and smaller adenomas (adjusted OR, 5.63; 95% CI, 2.84- 11.15 for ≤5 mm; adjusted OR, 3.18; 95% CI, 1.60-6.30 for 6-9 mm, respectively) were more frequently missed than pedunculated/sub-pedunculated adenomas and larger adenomas. In patients with 2 or more polyps compared with only one detected (adjusted OR, 2.37; 95% CI, 1.55-3.61 for 2-4 polyps; adjusted OR, 11.52; 95% CI, 4.61-28.79 for ≥5 polyps, respectively) during the first endoscopy, the risk of missing an additional polyp was significantly higher. One-quarter of neoplastic polyps was missed during colonoscopy. We encourage endoscopists to detect smaller and flat or sessile polyps by using the optimal withdrawal technique.