Right Colon Polyp Miss Rates of Water Exchange and Carbon Dioxide Insufflation Colonoscopy

Inclusion Criteria: * Consecutive patients aged 45 years or older undergoing colonoscopy for screening, surveillance, and positive FIT will be considered for enrollment. Exclusion Criteria: * familial adenomatous polyposis and hereditary non-polyposis CRC syndrome, personal history of CRC or inflammatory bowel disease, previous colonic resection, obstructive lesions of the colon, gastrointestinal bleeding, allergy to fentanyl, midazolam or propofol, American Society of Anesthesiology (ASA) classification of physical status grade 3 or higher, mental retardation, pregnancy, and refusal to provide a written informed consent.