Prolonged in vitro hemolysis of EDTA-anticoagulated blood after a delayed hemolytic transfusion reaction.

BACKGROUND: A novel case where in vitro hemolysis was observed in plasma, but not in serum samples, obtained after the onset of a severe delayed hemolytic transfusion reaction is presented., CASE REPORT: A 54-year-old woman received 2 units of blood during an orthopedic procedure. She had received transfusion 30 years earlier, and testing before transfusion revealed no alloantibodies. The patient returned 12 days after the transfusion with a Hb level of 54 g per L due to a severe delayed hemolytic reaction caused by anti-K. The plasma and serum samples were grossly hemolysed on Day 12. On Day 14, the serum samples showed no evidence of hemolysis; however, the EDTA sample remained grossly hemolysed. This discrepancy was not identified until Day 19. Due to concerns of ongoing apparent severe hemolysis, the patient was unnecessarily treated with IVIG and corticosteroids. The in vitro hemolysis was still present at 75 days, despite complete normalization of her Hb, bilirubin, and LDH levels. The phenomenon had resolved by 125 days., CONCLUSION: This in vitro artifact has not been previously reported and the mechanism remains unclear. Both plasma and serum samples should be observed for hemolysis when evaluating a patient with a severe delayed hemolytic transfusion reaction.