Section 4.6
Transfusion Reactions

A 92-year-old male diagnosed with anemia and episodes of frequent falling was typed as B negative and transfused 1 unit of packed red blood cells, also B negative. He was not recently transfused, and the antibody screen was negative. During the transfusion, his temperature rose from 36.2°C to 36.4°C, his pulse rose from 96 to 124, respirations from 18 to 20, and BP from 127/81 to 174/83. He was transfused with 205 mL before a reaction was called by the transfusionist. The postspecimen DAT was negative and clerical check acceptable. Urinalysis yielded 1+ blood with 5 RBCs microscopically. Other symptoms included tachycardia and flushing.
What reaction had most likely taken place?