Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 38-year-old man is evaluated during a routine examination. He was diagnosed with ulcerative colitis 10 years ago and is currently asymptomatic. His last colonoscopy, performed at the time of diagnosis, showed mildly active extensive colitis extending to the hepatic flexure. There is no family history of colon cancer or colon polyps. His only medication is mesalamine.
On physical examination, vital signs are normal. Abdominal examination is normal. Laboratory studies, including a complete blood count, liver chemistry studies, and C-reactive protein, are normal.
Which of the following is the most appropriate colonoscopy interval for this patient?
A: Colonoscopy now and every 1 to 2 years
B: Colonoscopy now and every 5 years
C: Colonoscopy every 5 years starting at age 40
D: Colonoscopy every 10 years starting at age 40
MKSAP Answer and Critique
The correct answer is A: Colonoscopy now and every 1 to 2 years. This item is available to MKSAP 16 subscribers as item 9 in the Gastroenterology and Hepatology section.
MKSAP 16 released Part A on July 31. More information is available online.
The most appropriate management for this patient is colonoscopy now and every 1 to 2 years. Patients with ulcerative colitis with disease extending beyond the rectum are at an increased risk of colorectal cancer. Cancer risk has been widely reported to be between 0.5% and 1% per year after having extensive disease for 10 years or more. The exact risk for an individual patient is uncertain and is probably based on the duration and extent of disease, severity of inflammation, and other personal factors. Based on this increased cancer risk, routine surveillance colonoscopy with biopsies every 1 to 2 years is warranted beginning 8 to 10 years after diagnosis. Because cancers associated with ulcerative colitis tend to arise from the mucosa as opposed to the usual adenoma-cancer sequence, biopsies are taken from flat mucosa throughout the colon and are evaluated for dysplastic changes. A finding of flat, high-grade dysplasia is grounds for recommending colectomy owing to the high rate of concomitant undetected cancer. A finding of flat, low-grade dysplasia warrants colectomy or continued surveillance colonoscopy at more frequent intervals.
Colonoscopy now for this patient is appropriate, but the interval should be every 1 to 2 years rather than every 5 years. For persons without ulcerative colitis but with a family history of colorectal cancer in a first-degree relative, screening is initiated either at age 40 years or beginning 10 years earlier than the diagnosis of the youngest affected family member. Colonoscopy every 10 years starting at age 40 is not appropriate for this patient.
- Patients with ulcerative colitis with disease extending beyond the rectum should undergo routine surveillance colonoscopy with biopsies every 1 to 2 years beginning 8 to 10 years after diagnosis.
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