In outpatient clinics and wards, we often encounter patients who need colonoscopy, and many people are confused about why they need colonoscopy, what to pay attention to before and during the examination, and what to do after the colonoscopy. Today we will talk about colonoscopy. What is colonoscopy? Colonoscopy, commonly known as colonoscopy. It is mainly composed of three parts: camera, conduction fiber, and display screen. It is inserted through the anus into the large intestine and looks retrogradely at the anus, rectum, sigmoid colon, descending colon, splenic flexure of the colon, transverse colon, hepatic flexure of the colon, ascending colon, cecum, and terminal ileum. What can colonoscopy do? In addition to direct observation of intestinal lesions, we can clamp tissue biopsy, microscopic resection, ligation to stop bleeding, injection of sclerosing agents, spraying of drugs, and placement of drainage tubes for suspected lesions. Why do we need colonoscopy? The incidence of colon cancer is increasing year by year, and colon cancer has been one of the major killers that seriously endanger the health of middle-aged and elderly people in China. Through the mirror, not only can intestinal lesions be clearly detected, but also some intestinal lesions can be treated, which is the main tool that cannot be replaced by other treatment methods. Who needs colonoscopy? Patients with the following problems need to undergo colonoscopy: those with unexplained diarrhea, blood in stool (positive occult blood in stool), change in stool habit, change in stool shape; those with abdominal masses accompanied by weight loss or/and anemia; those who find metastatic adenocarcinoma and need to find the primary lesion; those with family history of colon cancer or familial intestinal polyps; those who are at high risk of colorectal cancer screening; those who have postoperative review of colorectal cancer and colorectal polyps, etc. Healthy checkups are also allowed, but not routinely recommended. What are the precautions before colonoscopy? The first night, you should abstain from eating or drinking, take oral laxatives and drink a lot of water to cleanse your intestines through repeated artificial “diarrhea”. How is a colonoscopy performed? The colonoscopy is performed with both knees bent, in a left lateral position, with the anus exposed and the doctor standing behind, with the colonoscope entering through the anus. You will experience discomfort or mild pain during the doctor’s insertion of the mirror and turning, which can usually be tolerated. In addition, the doctor needs to inject air into the intestinal cavity in order to observe the intestinal canal. You may have a feeling of abdominal distension or even farting, please do not be nervous. Tips: The purpose of taking laxatives is to clean out the intestines, so please follow the doctor’s instructions on how and when to take laxatives; the best result of intestinal cleansing is clear or yellowish stools without fecal residue; the doctor will ask you to take off your pants and expose your anus, so don’t feel embarrassed; after the doctor inserts the mirror, he will inject gas to dilate the intestines, so you will feel bloated. After the examination, rest in the lounge for 30 minutes and leave only when there is no discomfort or with the doctor’s consent; after the colonoscopy, fast for 1-2 days as requested by the doctor and pay attention to whether there is abdominal pain, blood in the stool and other symptoms, and inform your doctor.