How does the presence of primary sclerosing cholangitis affect colorectal cancer surveillance in ulcerative colitis?

• A. Surveillance frequency is decreased with PSC
• B. Surveillance frequency is increased with PSC
• C. PSC has no effect on surveillance
• D. Surveillance intervals are unchanged

Answer: (D)

The key idea is that having primary sclerosing cholangitis with ulcerative colitis raises the risk of colorectal cancer, so surveillance needs to be more frequent. In UC without PSC, colonoscopic screening is typically done every 1–2 years after a certain duration of disease. But with PSC, the cancer risk is higher and can include flat dysplasia that is easy to miss, even when inflammation is not severe. To catch dysplasia early, annual colonoscopy with careful mucosal inspection—often using chromoendoscopy or high-definition techniques and taking multiple biopsies—is recommended. So, surveillance intervals are shortened to about yearly, rather than remaining unchanged or being spaced out.