What type of transfusion reaction is considered the most severe?

The most severe type of transfusion reaction is indeed ABO incompatibility. This type of reaction occurs when a patient receives blood containing A or B antigens that are not compatible with their own blood type. The immune system recognizes these foreign antigens as threats, leading to an acute hemolytic reaction where the body rapidly destroys the transfused red blood cells.

This severe immune response can result in a cascade of complications, including severe hemolysis, renal failure, shock, disseminated intravascular coagulation (DIC), and even death if not promptly recognized and treated. The signs and symptoms can occur almost immediately upon receiving the transfusion, making ABO incompatibility a critical concern in transfusion medicine.

Other types of transfusion reactions, while they can also be serious, generally do not lead to the same level of acute systemic complications or life-threatening conditions as ABO incompatibility. For example, Rh incompatibility primarily involves issues related to pregnancy and not typically acute transfusion reactions. Febrile reactions are often mild and arise from the recipient's reaction to white blood cells in transfused blood, and non-ABO hemolytic reactions, although potentially severe, typically are less acute than those associated with ABO incompatibility.