Unleash Your Inner Blood Banking Expert with the ASCP SBB Practice Exam 2025 – Your Path to Certification Success!

The most common serious immediate adverse effect of blood transfusion is a hemolytic transfusion reaction. This kind of reaction occurs when the recipient's immune system reacts against transfused red blood cells that are recognized as foreign due to incompatibility in blood type or presence of antibodies. It can lead to a range of symptoms, including fever, chills, back pain, and dark urine, and in severe cases, it can result in acute renal failure or disseminated intravascular coagulation.

While urticaria, or hives, can occur as a less severe form of allergic reaction to blood transfusions, it usually doesn't classify as a serious adverse effect. On the other hand, hepatitis from transfusions is typically a concern with past infections or poorly screened blood products, but with advancements in screening and testing, it has become far less common. Bacterial contamination can indeed lead to severe complications, but it is not as frequently encountered as hemolytic reactions, which remain the most prevalent immediate serious adverse effect in transfusion medicine.