The reason that blood tests are no longer performed before colonoscopy is that as long as the colonoscopy is sterilized to the required level, there is no need to test the blood, as the possibility of cross-infection is relatively small. Some hospitals also need to provide tests for hepatitis C, AIDS and syphilis before doing colonoscopy, in addition to the preparation for bowel cleansing, while there is no absolute requirement for hepatitis B surface antigen, and the diagnostic and therapeutic technology of colonoscopy has been improved, with less chance of cross-infection. Emergency colonoscopy and non-emergency colonoscopy are also somewhat different, the sterilization and configuration of emergency colonoscopy is somewhat different from that of non-emergency endoscopy, and the three items of transaminase, hepatitis B surface antigen, and infection are required to be provided. The relevant preparation before carrying out colonoscopy, it is recommended that you can consult the gastroenterology department of the regular hospital.