Colorectal cancer screening program has been proven to reduce colorectal cancer (CRC) mortality and is cost-effective. It has been adopted by most countries in the world, and colonoscopy is regarded as the most accurate test for detecting colorectal neoplasm. After screenees underwent colonoscopy, most endoscopists do not routinely explain the preliminary optical diagnosis to the subjects before they going home, which may cause unnecessary anxiety and may reduce the quality of life of the subjects before acquiring the final results. In recent years, endoscopic optical diagnostic technology has been validated by meta-analysis studies as an excellent tool to predict the histology of colorectal polyps and to differentiate the invasion depth of colorectal cancer. The real time feature of endoscopic optical diagnosis allows endoscopists to explain the preliminary results confidently to the subjects immediately after colonoscopy, which is expected to reduce the anxiety of the subjects before they acquired the final results and improve their quality of life. We designed a randomized controlled trial to validate whether real-time endoscopic optical diagnosis could decrease the anxiety burden and improve the quality of life for colorectal-cancer screenees after colonoscopy.

Inclusion Criteria:

• Patients who preparing to received screening or surveillance colonoscopy under general anesthesia.
• Patients who preparing to received sedated colonoscopy due to other GI tract related symptoms.

Exclusion Criteria:

• Impaired mental status that could not understand the questionnaire questions.
• Patients with major psychological disorders.