The Best Dosage and Timing of Polyethylene Glycol for Bowel Preparation Before Capsule Endoscopy

Inclusion Criteria: * Patients aged between 18 and 75 years and referred to capsule endoscopy because of suspected small-bowel disease are prospectively eligible for entry into the study. Exclusion Criteria: * Age \< 18 or \> 75 years * Known or suspected GI stricture or fistula * A history of GI tract resection * Swallowing disorders * Intensive therapy with fasting and parenteral nutrition;with a disease that may reduce movement of the GI tract, such as diabetes mellitus * Medications that could affect gastrointestinal movement within one week * Implanted with a medical electronic device * Active inflammatory bowel disease, toxic megacolon, toxic colitis * Severe pulmonary, cardiac, renal, or hepatic disease * Uncontrolled hypertension (systolic blood pressure\>170 mm Hg, diastolic blood pressure\>100 mm Hg); * Disturbance of electrolytes * Pregnancy or lactation * Patients inability to provide written voluntary informed consent * Participation in another clinical study