Low risk adenomas: 1 to 2 tubular adenoma(s) less than 10 millimeters in diameter with no high-grade dysplasia. All adenomas are dysplastic by definition and low risk adenomas only contain low grade dysplasia.
High risk adenomas (also called advanced adenomas): Tubular adenoma 10 millimeters in diameter or greater, 3 or more adenomas, adenoma(s) with villous histology or adenoma with high-grade dysplasia.
Serrated adenomas: Either sessile serrated adenomas (also called “sessile serrated polyps” or “sessile serrated adenoma/polyp”) or traditional serrated adenomas. Most serrated polyps will not have any dysplasia; serrated polyps with dysplasia are considered advanced. Traditional serrated adenomas are uncommon and are often protuberant and left-sided.
Serrated polyposis syndrome: At least 5 serrated polyps proximal to the sigmoid colon, with 2 or more being more than 10 millimeters, or any number of serrated polyps proximal to the sigmoid colon in someone who has a first-degree relative with serrated polyposis, or 20 or more serrated polyps of any size distributed throughout the colon.
Clearing colonoscopy: Repeat procedure performed to ensure that all neoplasia has been removed from the colon. A clearing colonoscopy is performed earlier than a surveillance colonoscopy.
Hyperplastic polyps: hyperplastic polyps are very common and usually occur as diminutive (less than 5 millimeters) non-dysplastic polyps in the rectum and sigmoid colon. These polyps are not associated with an increased risk of developing colorectal cancer and are therefore not considered to be screen-relevant lesions.