FCEM2-0774
A 45-year-old man receives a blood transfusion for anemia secondary to gastrointestinal bleeding. During the transfusion, he complains of experiencing alternating sensations of heat and cold during the second unit, and his temperature is measured at 38.1ºC. His temperature before the transfusion was measured at 37ºC. He feels fine otherwise and does not have any other symptoms.
Which of the following transfusion reactions is most likely to have taken place?