Adenoma miss rate of polypectomy-referring hospitals is high in Korea

Background/Aims: We evaluated the miss rates of polyps, adenomas, and advanced neoplasia of polypectomy-referring hospitals and risk factors for missed adenomas. Methods: We compared medical records and electronic images of initial colonoscopies from polypectomy-referring hospitals with those of corresponding therapeutic colonoscopies from Seoul St. Mary's Hospital obtained from May 2014 to February 2016. Results: A total of 147 patients (56.6 ± 12.1 years, 37 females) were included. The mean number of polyps and adenomas detected on initial colonoscopy was 2.4 ± 1.7 and 1.7 ± 1.4, respectively. The mean number of additionally detected polyps and adenomas per patient during therapeutic colonoscopy was 1.4 ± 1.8 and 1.0 ± 1.5, respectively. Pooled miss rate for polyps, adenomas, and advanced neoplasia was 36%, 37%, and 11%, respectively. Pooled miss rate for adenomas was significantly higher for right-sided, non-pedunculated, and small (< 1 cm) adenomas (p = 0.031, p = 0.000, and p = 0.000, respectively). The miss rate of polyps, adenomas, and advanced neoplasia per patient was 60%, 49%, and 7%, respectively. Multivariate analysis revealed age and number of adenoma on initial colonoscopy were significantly related with risk for adenoma-missing (p = 0.005 and p = 0.023, respectively). Conclusions: Among patients referred for polypectomy, adenoma is missed in one of two patients and advanced neoplasm is missed in one of 13. Patients with advanced age or multiple adenoma on initial colonoscopy have a higher possibility of missed adenoma. Total colon exploration should be performed carefully during therapeutic colonoscopy.