What is the likely cause of a 2°C temperature rise during a blood transfusion with no abnormal findings?

A 2°C temperature rise during a blood transfusion, especially when there are no other abnormal findings, is most indicative of a febrile non-hemolytic reaction. This type of reaction is quite common and typically occurs due to the recipient’s immune response to the white blood cells or platelets in the transfused blood product.

The rise in temperature is caused by the release of pyrogens, which can occur when the transfusion contains residual immune components. Unlike acute hemolytic reactions, which are often associated with hemolysis of red blood cells and can cause additional symptoms like chills and back pain, febrile non-hemolytic reactions are generally mild and do not present with hemolysis.

In this case, the absence of other abnormal findings like hives or respiratory distress makes it less likely that an allergic reaction or transfusion-associated lung injury is the cause. While allergic reactions can manifest with fever, they usually also present with urticaria or itching, which have not been mentioned here. Therefore, the temperature rise without further complications aligns well with the characteristics of a febrile non-hemolytic reaction, making it the correct answer.