Which type of transfusion reaction is immediate and causes hemolysis?

The type of transfusion reaction that is immediate and causes hemolysis is the acute hemolytic reaction. This reaction occurs when there is a rapid destruction of red blood cells due to an incompatibility between the donor's blood and the recipient's blood, typically involving ABO or Rh factor mismatches. The immune system reacts swiftly, causing the recipient’s body to attack the transfused red blood cells, leading to hemolysis.

Acute hemolytic reactions can manifest within minutes of transfusion and are characterized by symptoms such as fever, chills, back pain, and sometimes shock. The immediate nature of this response is linked to pre-existing antibodies in the recipient’s bloodstream that target the transfused cells, leading to this rapid and serious complication.

In contrast, the other types of reactions mentioned, such as febrile non-hemolytic reactions, delayed hemolytic reactions, and allergic reactions, do not lead to immediate hemolysis. Febrile non-hemolytic reactions are typically symptomatically milder and occur due to cytokine release without hemolysis. Delayed hemolytic reactions occur days to weeks after the transfusion as the immune response builds up over time. Allergic reactions usually involve mild symptoms that do not