Inclusion Criteria:  Any patient with a clinical indication for receiving same day bi-directional endoscopies.  Exclusion Criteria:  Contraindications of colonoscopy: acute peritonitis; intestinal perforation or suspected intestinal perforation; acute anorectal infection or painful lesions; menstruation; pregnancy; cardiopulmonary insufficiency; prior abdominal and pelvic surgery. Contraindications for EGD: severe heart disease, severe heart failure; severe lung disease: asthma : severe hypertension; acute perforation of esophagus, stomach and duodenum; acute severe pharynx and larynx disease gastroscopy can not be inserted; acute stage of corrosive esophageal injury; prior upper digestive tract operation. Contraindications for oral intestinal laxative: severe gastrointestinal obstruction or stricture; toxic megacolon; severe acute intestinal infection; dysphagia; disturbance of consciousness; allergy to drug ingredients. Allergic to emulsions or opioids. ASA score ≥ III