Clinical meaning
Acute Hemolytic: ABO incompatibility leads to IgM antibodies attacking donor RBCs, causing complement activation, massive hemolysis, and inflammatory cytokine release (Shock/DIC). Febrile Non-Hemolytic: Cytokines released from donor leukocytes accumulate during storage.
Diagnosis & workup
Diagnostics & workup: - Order direct antiglobulin test (DAT/Direct Coombs) for hemolytic reaction - Order free hemoglobin (serum and urine) to confirm hemolysis - Order haptoglobin (decreased in hemolysis) - Order repeat type and crossmatch to identify antibodies - Order DIC panel (fibrinogen, D-dimer, PT/PTT) for acute hemolytic reaction - Order CBC with peripheral smear (schistocytes indicate MAHA) - Order urinalysis for hemoglobinuria - Order tryptase level for anaphylactic reaction
Risk factors: - Previous transfusion reaction history - Multiple prior transfusions - IgA deficiency (anaphylaxis risk) - Alloimmunization - Immunocompromised state - Emergency transfusion without full crossmatch - Chronic transfusion dependence