Clinical presentation of delayed hemolytic transfusion reactions and hyperhemolysis in sickle cell disease.

Red blood cell (RBC) transfusion therapy is a key component in the comprehensive management of patients with sickle cell disease (SCD). Consequently, most adult SCD patients will receive at least one, and many will receive more than a hundred RBC transfusions in their lifetime. SCD patients develop RBC alloantibodies much more frequently than non-SCD transfused patients, which often make the selection of compatible RBCs extremely difficult, in addition to placing patients at significantly higher risk of suffering from delayed hemolytic transfusion reactions (DHTRs). Similar to alloimunization, DHTRs are much more common in patients with SCD compared to other heavily transfused populations, and are particularly consequential due to their propensity to cause hyperhemolysis, a life-threatening phenomenon in which both transfused RBCs in addition to the patient's own sickle-erythrocytes are destroyed. In this review, we highlight the incidence and pathophysiology of DHTRs; illustrate common presentations, appropriate evaluations and outcomes of DHTRs in patients with SCD; and discuss strategies for preventing or reducing the likelihood of DHTRs from occurring.