Quality Control of Esophagogastroduodenoscopy Using Real-time EGD Auxiliary System

Inclusion Criteria: * patients undergoing EGD examination with anaesthesia; * patients able to give informed consent. Exclusion Criteria: * patients with the contraindications to EGD examination; * patients with a prior EGD examination within 1 year before the trial; * patients with frankly upper gastrointestinal malignant lesions that were apparent on endoscopy; * a history of upper gastrointestinal cancers; * allergic to anaesthetic in previous medical history; * patients refused to participate in the trial; * the EGD procedure cannot be completed due to stenosis, obstruction, solid food, or complications of anaesthesia.