BACKGROUND: Patients with ulcerative colitis (UC) are at high risk of colonic dysplasia. Therefore, surveillance colonoscopy to detect early dysplasia has been endorsed by many professional organizations.OBJECTIVES: To determine whether gastroenterologists at Hamilton Health Sciences (Hamilton, Ontario) adhere to recommendations for UC surveillance issued by the Canadian Association of Gastroenterology and to retrospectively assess the incidence and type of dysplasia found and the subsequent outcome of patients with dysplasia (ie, colorectal cancer [CRC], colectomy, dysplasia recurrence).METHODS: A retrospective chart review of all patients with UC undergoing colonoscopy screening at Hamilton Health Sciences from January 1980 to January 2005, was performed. Patients were classified by the extent of colonic disease: limited left-sided colitis (LSC), pancolitis and any disease extent with concurrent primary sclerosing cholangitis.RESULTS: A total of 141 patients fulfilled eligibility criteria. They underwent 921 endoscopies, including 453 for surveillance, which were performed by 20 endoscopists. Overall, screening was performed on 90% of patients, and surveillance at the appropriate time in 74%. There was a statistically significant increase in the mean number of biopsies per colonoscopy after the guidelines were published (P<0.01 for all categories). Colonic dysplasia was detected in 24 of 141 patients (17.0%), with 17 of 24 (70.8%) found at surveillance. Two patients (8.3%) had CRC successfully treated. The average age of patients with dysplasia was 56.1 years, with a mean disease duration of 10.9 years in LSC versus 11.8 years in pancolitis (P not significant). Colectomy was not recommended for any patient with flat dysplasia. No patients progressed to high-grade dysplasia or CRC. Patients with pancolitis had a higher incidence of neoplasia (21% [18 of 86]) than patients with LSC (12% [6 of 49]; P=0.24). Forty-one patients (29.5%) had at least one hyperplastic or inflammatory polyp.CONCLUSIONS: For the majority of patients who underwent surveillance colonoscopies, their procedures were performed within the recommended time intervals, and biopsy compliance has improved. Dysplasia tended to arise after approximately 10 years of disease duration and in middle age, with flat dysplasia being rare. Interventions resulted in no dysplasia progressing to CRC, implying successful prevention.