Long-standing ulcerative colitis is associated with an increased cancer risk. Chromoendoscopy with dye spraying can detect subtle abnormalities that are not visible with standard endoscopy. The purpose of this study is to determine if chromoendoscopy with fewer "targeted biopsies" can replace standard colonoscopy with multiple "random" biopsies.

Patients with ulcerative colitis (UC) are at increased risk for colon cancer. Current guidelines recommend periodic surveillance colonoscopy in individuals who fulfill certain high-risk criteria. Endoscopists must perform a high number of biopsies (over 33 per patient) in order to increase the yield of such procedures. Chromoendoscopy (CE) has the ability to identify subtle lesions that are otherwise missed by standard endoscopy. Whether CE can replace standard colonoscopy in the surveillance of patients with UC is unknown.

Comparison: both standard biopsies and targeted biopsies will be obtained during colonoscopy from patients with UC who are candidates for surveillance colonoscopy. The yield of the two methods will be compared based on the number of biopsies required to identify one dysplastic (precancerous) lesion.

Inclusion Criteria:

• Ulcerative colitis, pancolitis > 8 years; left-sided > 15 years or
• history of PSC or
• history of previous dysplasia on colon biopsies or
• family history of colon cancer in first degree relative

Exclusion Criteria:

• any condition that precludes colonoscopy
• expected survival less than 1 year

Patients with ulcerative colitis satisfying criteria for surveillance colonoscopy