Size, Shape, Histology and Distribution of Colorectal Polyps Using High Definition Colonoscopes

Abstract

Purpose: High definition (HD) colonoscopes may detect more colorectal polyps, especially small flat lesions. We sought to characterize the distribution and shape of polyps detected by a single individual with a known high adenoma detection rate using HD colonoscopes. Methods: Patients were excluded for indications other than screening or surveillance. Patients with polyp syndromes were excluded. 974 patients underwent colonoscopy by a single examiner using HD Olympus colonoscopes and had ≥ 1 polyp identified. All polyps were prospectively identified by location (endoscopic estimate), size (endoscopic estimate), shape (Paris classification) and histology (each submitted separately for pathology). Results: There were 3207 polyps. 57% of all polyps were adenomas. Of adenomas, 86% were ≤ 5mm and only 5.2% were ≥ 10 mm. Of hyperplastic polyps, 88% were ≤ 5 mm, and 4.7% were ≥ 10 mm. 69% of all adenomas and 36% of all hyperplastic polyps were located in the proximal colon (p < 0.0001). The mean size of polyps was 3.9 mm and IIa lesions were smallest (mean 3.1 mm) followed by 1s polyps (3.5 mm) and Ip polyps were largest (7.1 mm) (p=0.0001). Overall 53% of lesions were IIa, 43% Is and 4% Ip. 7% of adenomas were Ip compared to 1% of hyperplastic polyps (p=0.0001). 53% of both hyperplastic and adenomatous polyps were IIa. There was a trend toward IIa lesions being more common in surveillance than screening (56% vs 50%;p=.06). 54% of IIa lesions were in the proximal colon, compared to 58% of Is polyps and 34% of Ip polyps (p<0.0001). 56% of IIa adenomas, 40% of Is adenomas and 4% of Ip adenomas were ≤ 5 mm in size. 55% of IIa hyperplastic lesions, 43% of Is hyperplastic polyps, and 1% of Ip hyperplastic polyps were ≤ 5 mm in size. Conclusion: The distribution of colorectal polyps in patients examined using high quality technique and HD colonoscopes is distributed further toward small and diminutive lesions than prior reports. Flat (IIa) lesions are common (about half of both adenomas and hyperplastic polyps/lesions), and on average are smaller than sessile and pedunculated polyps. Flat lesions are common on both sides of the colon and are common in both screening and surveillance examinations. Disclosure: Olympus - speakers bureau.