When there is a change in bowel habits, abdominal pain, diarrhea, localized abdominal masses, unexplained wasting, mucus, pus and blood stools can do colonoscopy. 1. The appearance of changes in bowel habits, may be due to intestinal polyps or intestinal tumors caused by the emergence of this case need to do colonoscopy to carry out the examination, for the diagnosis of the disease has a certain role. 2. If the patient has lower abdominal pain, chronic diarrhea, constipation, may also be due to ulcerative colitis or intestinal tumors and other diseases, at this time you can also do colonoscopy. 3. If there is a lump in the abdomen or a local bulge, if you suspect that there is a tumor in the intestines, you can also confirm the diagnosis by colonoscopy. 4. Patients with unexplained emaciation and suspected intestinal tumor should undergo colonoscopy in time to exclude intestinal cancer. 5. Mucus, pus and blood stools, mostly seen in acute enteritis, chronic colitis, Crohn’s disease, dysentery and other intestinal diseases, enteroscopy has a certain role in diagnosis. Patients should consult the doctor in time and follow the doctor’s instruction to carry out examination for clear diagnosis.