This multicenter randomized controlled trial evaluates whether a pre-procedural risk score-based endoscopist assignment strategy reduces intraprocedural pain in high-risk patients undergoing unsedated colonoscopy. High-risk patients (risk score \>5) are randomized 1:1 to either the intervention group (examination performed by expert endoscopists with ≥5,000 colonoscopy experiences) or the control group (examination performed by endoscopists assigned per routine hospital scheduling). The primary outcome is the proportion of patients reporting moderate-to-severe pain during colonoscopy, assessed by a blinded research assistant using a 4-point VRS. A total of 106 high-risk patients will be enrolled from two centers in China.