Hello. A blood transfusion consent form must be signed before blood transfusion, because blood transfusion may cause transfusion-related diseases, such as hepatitis infection, blood transfusion reaction, etc. Although the blood products in the hospital come from regular blood stations and undergo strict testing, some viruses are in the window period and cannot be detected, so the incidence rate is very low. Patients will also be informed about the risks of blood transfusions.