A patient shows fever, nausea, hypotension, and shock after receiving blood from an O- donor. What transfusion reaction are they most likely experiencing?

The symptoms presented by the patient—fever, nausea, hypotension, and shock—are indicative of a septic transfusion reaction. This type of reaction typically occurs due to the presence of bacteria in the blood product, which can lead to systemic inflammatory response and sepsis. The rapid onset of these severe symptoms suggests that the patient is experiencing a reaction to the transfused blood that involves infection, potentially from improperly stored or contaminated blood products.

In contrast, hemolytic reactions are primarily characterized by fever, chills, and back pain due to the destruction of red blood cells, rather than the significant hypotension and shock seen in this scenario. Anaphylactic reactions would present with symptoms such as urticaria, swelling, and respiratory distress, rather than the generalized symptoms of fever and severe hypotension. Febrile reactions are more related to fever and chills due to the recipient’s immune response to white blood cells or plasma proteins in the transfused product, but they do not usually cause shock or severe hypotension.

Thus, the combination of the signs and symptoms described points more towards a septic reaction as the underlying cause.