What is a transfusion reaction?

Antibody-Ag reaction: A transfusion reaction is a reaction between donor RBC (red blood cell) antigens introduced into a recipient which has antibodies to at least one of these antigens. Depending on the antigen, the reaction can be mild. Moderate, or severe. A classic example is an rh reaction, where rh positive blood is given to rh negative recipient. This can be a mistake or in massive transfusion.

Immunologic or not: Causes for transfusion reactions may be immune related or not, also they can be acute (less than 24 hours) or delayed. These are some: hemolytic; febrile, non-hemolytic; bacterial contamination (septic shock); anaphylaxis; transfusion-related acute lung injury (trali); transfusion-associated circulatory overload (taco); graft vs. Host disease (ta-gvhd); iron overload; infections.