Water Exchange and CO2 Insufflation With Abdominal Compression Device to Reduce Manual Assistance

The goal of this trial is to evaluate whether water exchange colonoscopy and CO2-insufflation colonoscopy with an abdominal compression device (Maxbelt me3 type, Nippon Sigmax Co., Tokyo, Japan) can achieve a significantly lower proportion of patients requiring manual abdominal pressure during colonoscopic insertion compared with CO2 insufflation alone.

Inclusion Criteria: * Patients aged 45-80 years having an average risk for colorectal cancer who plan to undergo sedated outpatient colonoscopy for screening, surveillance, and those who have received a positive fecal immunochemical test result Exclusion Criteria: * Patients with hereditary colorectal cancer syndrome, including familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer (Lynch syndrome) * Patients with serrated polyposis syndrome * Patients with known or suspected inflammatory bowel disease * Patients with a history of colorectal cancer or other intra-abdominal malignancy * Patients with a history of colorectal resection * Patients with a history of abdominal aortic aneurysm, cirrhosis, ascites, or other severe comorbid illnesses * Patients with recent wounds or skin rash on the anterior abdominal wall and back * Patients with known ventral hernia * Patients with unsedated procedure * Patients with planned bidirectional endoscopy * Patients with body mass index \>35 kg/m2 * Patients with waist circumference \105 cm * Patients with known or suspected gastroparesis * Patients with planned therapeutic procedures (e.g., hemostasis, removal of a large polyp) * Patients with mental retardation * Pregnant women or those planning pregnancy * Patients unwilling to participate in the study