American Board of Internal Medicine (ABIM) Certification Practice Exam

What characterizes febrile nonhemolytic transfusion reactions?

1. Severe hypotension

2. Chills and fever

3. Hemolysis of red blood cells

4. Cardiac arrest

The correct answer is: Chills and fever

Febrile nonhemolytic transfusion reactions are primarily characterized by the onset of chills and fever following a blood transfusion. This type of reaction typically occurs due to the recipient’s immune response to leukocyte or platelet antigens present in the transfused blood components. The symptoms of chills and fever usually arise within a couple of hours of starting the transfusion, distinguishing this reaction from other more severe types. The temperature increase is often measured at least 1°C (1.8°F) above the baseline. These symptoms are not indicative of serious complications or hemolysis but instead reflect a relatively common and benign reaction that can occur during blood transfusions. The other options, such as severe hypotension, hemolysis of red blood cells, and cardiac arrest, describe much more serious complications that are associated with different types of transfusion reactions. For instance, hypotension and cardiac arrest could indicate an anaphylactic reaction or septic reaction, while hemolysis pertains specifically to hemolytic transfusion reactions, which are characterized by destruction of the transfused red blood cells rather than the febrile response observed here. Thus, identifying chills and fever is crucial for recognizing febrile nonhemolytic transfusion reactions.