Which of the following symptoms would best indicate a hemolytic transfusion reaction?

Fever, chills, and back pain are hallmark symptoms of a hemolytic transfusion reaction, particularly an acute hemolytic reaction where the recipient's immune system reacts against the transfused red blood cells. This reaction occurs when there is an incompatibility between the donor's and recipient's blood types leading to the destruction of red blood cells.

Fever and chills indicate an immune response, a common response when the body recognizes foreign substances. Back pain is specifically associated with this type of reaction, often due to the release of inflammatory mediators and the potential for damage to the kidneys as a result of hemolysis. Overall, the combination of these symptoms is a clear signal of a hemolytic process occurring in the body due to the transfusion.

Other symptoms listed, such as hypotension and urticaria, might suggest allergic reactions but are not specific indicators of hemolysis. Shortness of breath and wheezing could indicate an anaphylaxis response or pulmonary complications, while nausea and vomiting are more generalized symptoms that do not specifically point to a hemolytic reaction. Therefore, the combination of fever, chills, and back pain distinctly identifies a hemolytic transfusion reaction.