Paroxysmal nocturnal hemoglobinuria and the transfusion of washed red cells. A myth revisited.

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon, acquired clonal stem cell disorder primarily affecting red cells that have an abnormal sensitivity to complement lysis. Since 1948, the use of saline-washed red cells (WRBCs) has been advocated to minimize hemolysis after transfusion to patients with PNH. Thirty-eight years of experience (1950 through 1987) with patients who had PNH were reviewed. Twenty-three patients with a positive Ham's test had been transfused with 556 blood components, including 431 RBC products: 94 units of whole blood, 208 units of packed RBCs, 80 units of white cell-poor RBCs, 38 units of WRBCs, 5 units of frozen RBCs, and 6 units of intraoperatively salvaged RBCs. Only one documented episode of posttransfusion hemolysis related to the underlying diagnosis of PNH was found, and it was associated with the transfusion of a unit of type O whole blood to an AB-positive individual. This unit contained ABO-incompatible plasma; this case was similar to one in an earlier report from which originated the recommendation for using WRBCs. The posttransfusion increment in hemoglobin concentration in patients receiving ABO-identical packed RBCs was comparable to that in patients receiving frozen or washed RBCs. These findings indicate that the use of WRBCs is unnecessary and that patients with PNH should be transfused with group-specific blood and blood products.