The investigators prospectively recruited patients (aged ≥45 and ≤75 years) who were scheduled to undergo colonoscopy at our center. Patients were excluded if they had advanced colonic cancer, prior resection of the proximal colon, inflammatory bowel disease, or polyposis syndrome, or were unable to provide informed consent. In addition, if the quality of bowel preparation was unsatisfactory (Boston Bowel Preparation Scale [BBPS] score <2 in any segment of the colon), or if the cecum could not be intubated during the colonoscopy, patients were excluded.