Efficacy of Tailored Bowel Preparation Strategy Guided by a Predictive Model

Inclusion Criteria: * patients aged 18 or older * patients undergoing colonoscopy Exclusion Criteria: * patients with a history of colorectal surgery * patients with severe colonic stricture or obstructing tumor * patients with dysphagia * patients with compromised swallowing reflex or mental status * patients with significant gastroparesis or gastric outlet obstruction * patients with known or suspected bowel obstruction or perforation * patients with severe chronic renal failure (creatinine clearance\<30 ml/min) * patients with severe chronic renal failure (creatinine clearance\<30 ml/min) * patients with uncontrolled hypertension (systolic blood pressure\>170 mm Hg, diastolic blood pressure\>100 mm Hg) * patients with inflammatory bowel disease or megacolon * patients with dehydration * patients with dehydration * patients with pregnancy or lactation * patients hemodynamically unstable * patients unable to give informed consent