In outpatient clinics and wards, patients are often encountered in need of colonoscopy, and many people are confused as to why colonoscopy is necessary, what to pay attention to before and during the examination, and the precautions to be taken after colonoscopy. So today we will talk about the colonoscopy of those things. What is colonoscopy? Colonoscopy, commonly known as enteroscopy. It is mainly composed of three parts: camera, conductive fiber, and display screen. Inserted into the large intestine through the anus, retrograde observation of the anus, rectum, sigmoid colon, descending colon, splenic flexure of the colon, transverse colon, hepatic flexure of the colon, ascending colon, cecum, terminal ileum. What can colonoscopy do? In addition to direct observation of intestinal lesions, for suspicious lesions we can perform clamp tissue biopsy, microscopic resection, lancing hemostasis, injection of sclerosing agent, spraying medication, and placement of tubes for drainage and other treatments. Why colonoscopy? Colonoscopy has never been popular. Even if the examination is short and painless, many people shy away from it. In the United States, for example, about 40% of people who are recommended by their physicians to have a colonoscopy fail to do so. However, according to the U.S. Centers for Disease Control and Prevention (CDC), if everyone over the age of 50 undergoes colonoscopy, 60% of colon cancer deaths can be effectively prevented. In China, the incidence rate of colon cancer is increasing year by year, and it has become one of the major killers that seriously jeopardize the health of middle-aged and old people. Through colonoscopy not only can clearly find intestinal lesions, but also can treat some intestinal lesions, which is irreplaceable by other means of diagnosis and treatment at present. Who needs colonoscopy? Patients with the following problems need to undergo colonoscopy: unexplained diarrhea, blood in stool (positive for fecal occult blood), change in bowel habit, change in stool shape; abdominal mass accompanied by lethargy or/and anemia; metastatic adenocarcinoma is found, and it is necessary to search for the primary lesion; there is a family history of colon cancer or familial intestinal polyps; colorectal cancer high-risk group census; colorectal cancer and colorectal polyps postoperative follow-up, and so on. Healthy physical examiners can also, but not routinely recommended. What are the precautions before colonoscopy? The first three days of diet without residue, 6 hours before the examination began to take oral laxatives and drink a lot of water, through repeated artificial “diarrhea” to clean the intestinal tract. For people with constipation, the bowel preparation is more individualized. How is a colonoscopy performed? During a colonoscopy, the colonoscope is inserted through the anus by bending the knees and lying on the left side, exposing the anus, with the doctor standing behind. The process of inserting the mirror and turning the mirror by the doctor may cause discomfort or mild pain, which can usually be tolerated. In addition, the doctor needs to inject gas into the intestinal lumen in order to observe the intestinal tubes, and there may be a feeling of abdominal distension or even farting, so please do not be nervous.