Colorectal cancer, commonly known as colorectal cancer, is a common malignant tumor in China, second only to lung cancer and gastric cancer in terms of incidence rate, and with the change of diet and insufficient exercise, its incidence is showing a trend of younger and increasing year by year. Colonoscopy is the gold standard for screening colorectal cancer, which can detect early cancer or precancerous lesions. Many people are afraid of colonoscopy, but it is not necessary because “painless” colonoscopy has long been popular. A successful colonoscopy requires a clear surface of the colon mucosa, otherwise it will prolong the operation time and increase the risk of complications and missed lesions. Let’s talk about colonoscopy, you need to know those things. Fasting time Patients are prohibited from eating by mouth 6-8 hours before the colonoscopy (longer for those with known or suspected delayed gastric emptying)! No liquids (including water) 2 hours before the examination! For elective colonoscopy patients, it is recommended to avoid foods with high fiber content (fruits, vegetables, whole grains) from 3 days in advance, and to choose low residue meals (porridge, rice, noodles, cake, bread, steamed eggs, egg soup, tofu, bean curd, lean meat or fish). The dinner 1 day before the examination should be clear liquid (rice soup, soy milk, lotus root powder, fruit juice, vegetable juice), not milk! Third, oral laxatives The most widely used oral intestinal cleansers in clinical practice include compound polyethylene glycol electrolyte dispersion, mannitol injection, and sodium phosphate oral solution! Regardless of which laxative you choose, it is recommended to avoid giving it at once and take it in small doses for better results! Especially for patients who are examined in the afternoon! On the day before the examination, you can choose to take the medication orally one hour after dinner, and on the day of the examination, you can take it orally after waking up (at least 6-8 hours earlier than the examination time). You can take it orally at a rate of 1-1.5L per hour, and you will feel bloated almost an hour later. If you feel that the bloating is unbearable or abdominal pain occurs, you can temporarily slow down or suspend taking it, and continue taking it after the symptoms disappear. If you feel that the taste is not good you can cool the warm water or drink with a straw may be easier to take! Drug brewing method single dose taking time applicable people 1.Compound polyethylene glycol electrolyte dispersion (and cool) 1 bag (68.56g) dissolved in 1000ml warm water for 1 hour No irritation to intestinal mucosa, does not affect intestinal absorption and secretion, not easy to cause dehydration, will not lead to electrolyte disorders, suitable for most patients, but need to take more liquid amount, the patient’s tolerance is poor, may not be able to drink according to the amount 2.Compound polyethylene glycol electrolyte dispersion (Shu Tai Qing) 1 box (82.2g/total 12 packs) dissolved in 750ml warm water mannitol injection + 5% glucose sodium chloride solution 250ml + 500ml directly taken orally for 30 minutes intestinal non-absorption, no irritation to the intestinal mucosa, less dosage, easy for patients to accept, but the intestinal flora produce flammable hydrogen and methane in case of heat may cause explosion, not suitable It is not suitable for patients who need electrocoagulation (e.g. polypectomy). 1 bottle of sodium phosphate oral solution (45ml) dissolved in 750ml of warm water for 1 hour has good taste, less dosage, good patient compliance, but can cause renal impairment, fluid and electrolyte disturbance, not suitable for patients >65 years old, heart failure, renal insufficiency, decompensated cirrhosis or electrolyte disturbance. For patients with constipation who may require more frequent bowel movements to achieve their goal, pre-medication with a laxative (senna) or a combination of gastrointestinal stimulants (domperidone, mosapride) may be used to improve results. Poor bowel preparation may be detrimental to the patient’s ability to perform a colonoscopy and a more comprehensive bowel cleanse will have to be attempted, so strict adherence to the instructions for preparation is expected, so try to get it right in one sitting! Patients with chronic diarrhea should also take their medications as required, otherwise they will also not be able to meet the examination criteria and see the lesions in the intestine. Patients who do not follow the instructions for bowel preparation are advised to eat a clear liquid 2 days in advance, consider taking laxatives for 2 consecutive days, and schedule the colonoscopy in the morning! Do not drink too much too fast in order to meet the examination standards as soon as possible (may cause vomiting, the desire for speed is not achieved Oh) or add their own medication change (the intestine can not tolerate the stimulation, and may even die suddenly Oh)! Most drugs can be taken as usual, but some need to be adjusted, such as: 1, anti-platelet or anticoagulant drugs (aspirin, clopidogrel and warfarin, etc.): whether the need to stop the drug by the prescribing physician to operate the risk of bleeding and the possibility of thromboembolic events after discontinuation of the drug after weighing the decision. 2.Glucose-lowering drugs (insulin, metformin, etc.): the amount of food consumed by mouth before the examination is reduced, and taking it at the original dose may cause hypoglycemia, and the dose should be reduced or the administration should be suspended. 3, oral iron: stop using at least 5 days before the examination, iron will make the fecal residue black and sticky, not easy to discharge. 4.Angiotensin-converting enzyme inhibitor: It is recommended to stop using it on the day of oral intestinal cleanser and within 72 h afterwards. V. “Painless” medication Waiting for the examination, the anesthesiologist will open the intravenous access of the patient to be examined (i.e. “saline”), at this time, the input is only ordinary saline, so the patient will not fall asleep, so the patient does not have to worry if the anesthetic does not work. When it is the patient’s turn to examine, the physician will put propofol injection (like milk, oh) from the intravenous access drip into the patient, this may cause local pain, do not need to panic, will soon be relieved, close your eyes and deep inhalation for a few minutes and then you can fall asleep. The physician will monitor the patient’s heart rate, oxygen saturation, blood pressure and other parameters to ensure the patient’s safety. The patient will wake up within a few minutes after the examination is over and the “milk” drip is stopped, and may be a little dizzy and want to stay in bed to sleep comfortably, so you need to stay in the awakening area until you are fully awake and free of discomfort before you can leave. Patients are not recommended to drive themselves to the doctor on that day to avoid unnecessary accidents.