The more direct method of intestinal examination is colonoscopy, which is painless and easy for patients to accept. In addition to colonoscopy, other intestinal examinations can be done, including gastrointestinal imaging, barium enema, abdominal plain film, small bowel CT, capsule endoscopy, small colonoscopy, etc. Each examination has its own applicability to different groups of people. Chronic diarrhea, change in stool habit or character, patients with family history of intestinal cancer or colon polyps, people over 50 years of age, and people under 50 years of age with intestinal symptoms need to undergo colonoscopy to make a clear diagnosis.