MKSAP quiz: Colonoscopy after a sessile serrated polyp

This month's quiz asks readers to determine the appropriate interval for repeating colonoscopy in a 57-year-old woman whose most recent screening colonoscopy disclosed a 12-mm sessile serrated polyp in the ascending colon.


A 57-year-old woman is evaluated after a recent screening colonoscopy. The colonoscopy disclosed a 12-mm polyp in the ascending colon, which was removed. No other lesions were noted. On pathology, the lesion was found to be a sessile serrated polyp.

Physical examination findings are unremarkable.

Which of the following is the most appropriate time to repeat colonoscopy?

A. 1 year
B. 3 years
C. 5 years
D. 10 years


MKSAP Answer and Critique

Correct answer: B. 3 years. This item is available to MKSAP 17 subscribers as item 24 in the Gastroenterology & Hepatology section. More information about MKSAP 17 is available online.

Colonoscopy should be repeated in 3 years. The World Health Organization has classified serrated colorectal polyps into three categories: hyperplastic polyps, sessile serrated polyps, and traditional serrated adenomas. Hyperplastic polyps are believed to have no malignant potential, whereas sessile serrated polyps and traditional serrated adenomas are neoplastic. Sessile serrated polyps are thought to be the precursor of approximately 15% of sporadic colorectal cancers.

Recent guidelines have established recommendations for postpolypectomy surveillance colonoscopy intervals in patients with serrated polyps; the rationale for postpolypectomy surveillance is to detect recurrent neoplasia. Patients with large (≥10 mm) or dysplastic sessile serrated polyps or traditional serrated adenomas should undergo colonoscopy in 3 years.

A 1-year surveillance interval is recommended for patients with serrated polyposis syndrome. Serrated polyposis syndrome is a rare condition characterized by multiple or large serrated polyps, including hyperplastic polyps, sessile serrated polyps, traditional serrated adenomas, and possibly also adenomatous polyps. Patients with serrated polyposis syndrome are at increased risk of colorectal cancer.

The recommended postpolypectomy interval for patients with sessile serrated polyps smaller than 10 mm is 5 years. This patient's sessile serrated polyp is larger than 10 mm, so this recommendation is not appropriate.

A 10-year average-risk interval is recommended for patients with small rectosigmoid hyperplastic polyps, but it is not appropriate for this patient because her large sessile serrated polyp carries a higher cancer risk.

Key Point

  • For patients with large (≥10 mm) or dysplastic sessile serrated polyps or traditional serrated adenomas, the recommended postpolypectomy surveillance colonoscopy interval is 3 years.