 Patients with concurrent chronic ulcerative colitis and primary sclerosing cholangitis or patients with chronic ulcerative colitis and known colorectal dysplasia or cancer, presenting for surveillance colonoscopy will be recruited. After giving informed consent patients will then undergo colonoscopy in a segmental fashion. Colonoscopy with white light will be performed to the cecum and examination will be performed on withdrawal. First conventional white light will be used to examine the cecum and ascending colon and random biopsies will be obtained. All endoscopically apparent lesions will be biopsied separately. Immediately following will be examination of that segment of cecum and ascending colon under AFI first, then NBI with targeted biopsies of suspicious areas being taken. The AFI and NBI modality will be achieved by simply flipping a switch.. If necessary, washing of oozing blood from random biopsy sites will be performed., The remainder of the colon will be assessed in like fashion: transverse, descending and rectosigmoid. Because high definition endoscopy is the default modality, this will be in use throughout the procedure. 