1. Precautions before examination: 1. The day before the examination, a small amount of liquid food can be eaten for dinner, and the doctor will supplement energy according to the patient’s condition; 3 days before the examination, stop taking iron drugs, avoid taking aspirin-like drugs or other anticoagulants (if the patient takes them, stop taking them for at least 7 days before the operation); if intestinal polyps are suspected, those who are prepared for electrodesiccation are prohibited from eating milk and dairy products. 2, the physician should measure blood pressure, electrocardiogram, examination before the examination (patients who are considered to have polyps should check the blood routine, coagulation function). Contraindications: those with severe heart disease, cardiopulmonary insufficiency, severe hypertension, acute diarrhea, severe ulcerative colitis, colonic Crohn’s disease, peritonitis, pregnancy, mental illness, and those who have had multiple abdominal surgeries with obvious adhesions are prohibited from doing this examination. 3, intestinal preparation (find a doctor to prescribe laxatives): method one oral magnesium sulfate injection 150 ml after drinking 2000 ml of water within 30 minutes (no diabetes can be clear color drinks or sugar water), after taking more walking, such as no vomiting symptoms can continue to draw water 500 ml, the best effect is to discharge clear water-like stool. Method 2: Take 1 box of this product (containing 1 sachet each of A, B and C), pour the powder of each packet in the box into the cup (bottle) with scale, add warm boiled water to 1000ml, stir to make it dissolve completely, and then take it. Dosage: 2000ml, 600-1000ml for the first time, then 250ml every 10-15 minutes until finished, the best effect is clear water-like stool. Note: If patients have obstructive symptoms (frequent abdominal masses or bloating, pain), consider having tumors, larger polyps, please take under the guidance of a doctor, and prohibit taking large amounts of laxatives at once. 4, the examiners bring their own tissues, the elderly should be accompanied by a companion, such as previous colonoscopy or to perform colonoscopy treatment, please bring the previous colonoscopy results, one hour before the examination patients can take chocolate or sugar orally. 2.Post-examination precautions: 1.After biopsy or polypectomy, please rest in bed, do not exercise strenuously for three days, and do not do barium enema examination. After polypectomy, the doctor will generally fast for three days and give intravenous fluids according to your condition. If there is no blood discharge and the situation is satisfactory, you can be discharged from the hospital. 2.The biopsy specimen should be sent to the pathology department together with the disease examination sheet. 3.In the initial stage, you may feel bloating and discomfort due to air accumulation in the large intestine, but it will gradually disappear after a few hours. If the bloating is obvious, you should tell the doctor or nurse, who will give you the appropriate treatment. 4.If there is no special, you may take a general diet or eat according to the doctor’s prescription. 5.If there is persistent abdominal pain, or large amount of bleeding in the stool, you should tell the doctor in time to avoid accidents.