A postpartum woman was crossmatched for 2 units of packed re…

A postpartum woman was crossmatched for 2 units of packed red cells. The first unit was issued at 3:15 AM. At 3:45 AM, the nurse called the blood bank to say the patient had of fever of >38°C. The transfusion was stopped and a post-transfusion specimen was drawn. The unit and identification tags were returned to the blood bank. The DAT on the specimen was negative and hemolysis was absent. All visual and clerical checks were satisfactory. What type of transfusion reaction has occurred in this patient?