Such a reaction requires formation of antibodies and occurs exclusively in patients with a prior history of transfusion or pregnancy. Chronically transfused patients should always receive leukodepleted blood products to avoid febrile reactions to WBC's or plasma. Washed or frozen RBC's or IgA-deficient plasma may be needed to further transfusions. Characterized by fever, chills, urticaria, dyspnea , chest pain, abdominal or lower back pain, tachycardia , hypertension or hypotension , renal failure, and shock. Findings may include anemia, DIC, hemoglobinemia, hemoglobinuria, and a positive Coombs test.
Reactions are due to antibody-antigen interaction with consequent complement activation.
Treatment is immediate cessation of transfusion and administration of fluid, steroids, mannitol, and pressors as needed to maintain cardiovascular stability. Occasionally, patients receiving compatible red cells may experience symptoms of a hemolytic reaction 3 to 10 days later. These patients have been sensitized to one or more 'minor' blood group antigens during a prior transfusion. The titers may fall to undetectable levels between transfusions. During re-exposure, an anamnestic response occurs, and when sufficient antibody is produced, clinical hemolysis occurs.