The immune mediated destruction of donated blood cells, occurring about 3 to 5 days after a transfusion and often resulting from recipient antibodies against minor antigens on donor red cells. Delayed transfusion reactions are relatively uncommon except in patients who have received many previous transfusions and have become alloimmunized (e.g., patients with sickle cell anemia). A sudden drop in hemoglobin and hematocrit levels is a hallmark.