Yield of second surveillance colonoscopy to predict adenomas with high-risk characteristics

Background and aims: The yield of surveillance colonoscopies for patients with a history of polyps is well established for first surveillance, but limited for second surveillance. The aim of this study was to evaluate the proportion of high-risk adenomas at second surveillance colonoscopy based on findings of previous colonoscopies. Methods: This retrospective cohort study was conducted in a tertiary hospital and patients who had undergone three colonoscopies were included. Based on the findings at index colonoscopy, patients were categorized into three groups: high-risk adenoma (n = 252), low-risk adenoma (n = 158) or no-adenoma (n = 318). Findings of subsequent high-risk adenoma, low-risk adenoma and no adenoma at surveillance colonoscopies were documented in each group. Results: Among patients with high-risk adenoma at index and first surveillance colonoscopies, significantly higher rates of high-risk findings were found at second surveillance, compared with patients who had low-risk or no-adenoma at index colonoscopy and high-risk adenoma at first surveillance colonoscopy (58%, 33% and 10%, respectively, p < 0.001). Conclusions: Both index colonoscopy and first surveillance high-risk adenoma have an impact on incidence high-risk findings at second surveillance colonoscopy and these subjects need close surveillance.