People with a family history of intestinal disease, abnormal bowel manifestations, and previous illnesses such as intestinal tumors need to undergo colonoscopy. Enteroscopy is a kind of active screening for healthy people of appropriate age or high-risk groups without symptoms, and its indications are: 1. Those who have lower gastrointestinal symptoms such as blood in the stool, abnormal bowel movements, abdominal discomfort, etc. but the diagnosis is unknown. 2. Those who are suspected of having intestinal lesions by barium enema and need further confirmation of the diagnosis. 3. Abdominal mass, especially lower abdominal mass, who need to confirm the diagnosis. 4. Unexplained low intestinal obstruction. 5. Those who need regular follow-up after colon polypectomy for colon cancer. 6. Census of colon tumor, serious colon lesions in the family. 7. Unexplained emaciation and anemia. 8. Endoscopic resection of colon polyps and early colon cancer. 9. Intestinal torsion and intussusception reset. Colonoscopy need to go to the regular hospital for examination, usually need to make an appointment in advance, before the examination need to consult the doctor to clarify the precautions.