Colonoscopy is one of the most common means of diagnosing and treating colorectal diseases, and its indications include diarrhea, bloating, abdominal pain, blood in stool, changes in stool habits, such as alternating constipation and diarrhea, and changes in stool shape such as thinning. In order to better complete the colonoscopy and show the lesion more clearly, it is recommended that patients pay attention to the following aspects before the examination: 1, three days before the examination eat a semi-liquid diet, such as noodles, egg custard, yogurt, thin rice, etc., avoid eating celery, kelp, fungus, leek, dragon fruit and other coarse fiber food to ensure that the intestinal tract is fully prepared smoothly; if there are taking aspirin, clopidogrel hydrogen sulfate tablets, warfarin and other anti If you are taking aspirin, clopidogrel sulfate tablets, warfarin and other antiplatelet and anticoagulant drugs, you need to consult your doctor and stop taking them in advance as required; 2. Fasting on the day of examination, hypertension drugs are taken normally, but hypoglycemic drugs need to be stopped; 3. 4 hours before the examination, you need to take intestinal cleansers such as polyethylene glycol electrolyte dispersion, magnesium sulfate, mannitol, etc. under the guidance of your doctor. Patients who have constipation should take laxative drugs, such as laxative tablets and senna leaves, one week in advance to ensure that the intestines are emptied during the examination; 5. Before performing colonoscopy, it is necessary to perform electrocardiogram to assess the heart function; 6, pay attention to ensure sufficient sleep and avoid cold and strain; 7, before the examination, patients should wear loose clothing on the day to facilitate dressing and undressing, while relaxing and avoiding tension; 8, female patients need to avoid menstruation if performing colonoscopy.