Polyp Miss Rates by Colonoscopy Compared with Colon Resection Specimens

Abstract

Background: Colonoscopy is useful for the detection and removal of colonic polyps, but problems with quality control of colonoscopies are increasing as the number of colonoscopic examinations has increased as a result of increased health promotion programs. Although many studies have determined, by tandem colonoscopy reports, that the polyp miss rate using colonoscopy is approximately 25%, true miss rates are not certain since there is no gold standard for diagnosing colonic polyps with which to compare colonoscopy. Our study compared the number of polyps found by colonoscopy with the number of polyps in surgically resected colons to investigate how frequently colonoscopy might miss polyps and which factors could affect the polyp miss rate. Materials and Methods: We retrospectively analyzed 38 patients who underwent colon resection for colorectal cancer and had synchronous lesions in the resected portion. The miss rate was determined by comparing the number of polyps detected during colonoscopy with those present in the resected colonic segment. A statistical analysis was performed to determine the influences of the location, the pathologic type, and the size of the missed polyps on the colonoscopic miss rate. Results: We found 93 polyps in the resected colon specimens, 68 of which were detected during colonoscopy, so the overall colonoscopy miss rate was 26.9%. Of the 25 polyps missed during colonoscopy, 1 was ≥ 10 mm in size and 24 were < 10 mm. Colonoscopy failed to detect 9 of 69 adenomatous polyps, and 15 of 18 hyperplastic polyps. In the descending, transverse, ascending and sigmoid colon, the miss rates were 0%, 29%, 17%, and 22%, respectively. In conclusion, polyps <10 mm in size, hyperplastic polyps, and polyps in the rectum and cecum were missed most frequently. Conclusion: Colonoscopy is an effective method to diagnose and treat polyps, but we should not ignore the significant colonoscopy polyp miss rate. Endoscopists should pay more attention to finding synchronous lesions in patients with known colorectal cancers, and technical advances and quality control of colonoscopies are highly warranted so as to not miss these synchronous lesions.