The increasing use of fresh blood group O whole blood in acute trauma medicine makes it important to reevaluate the issue of hemolytic reactions related to the transfusion of ABO-incompatible plasma.


This review summarizes and evaluates published articles and case reports concerning hemolytic reactions in connection with the transfusion of group O whole blood or blood products to nongroup O recipients.


In 1945-1986, 15 nonmilitary publications reported hemolytic transfusion reactions with group O blood/blood products. All patients recovered except for two fatalities. Late in World War II and during the Korean and Vietnam wars and onward in Iraq and Afghanistan only “low anti-A, anti-B titer” group O whole blood has been used as universal blood. In spite of a large number of units transfused, there are no reports of hemolytic reactions. Twenty-five publications report hemolytic reactions after transfusion of group O platelets to nongroup O recipients. In all patients but one, the titer of the implicated A- or B-antibody was >100 (saline) or >400 (antiglobulin) and all cases with an infused volume of incompatible plasma <200 mL were related to anti-A or anti-B antiglobulin titers >1000.


In emergency lifesaving resuscitation, the risk of hemolytic transfusion reactions from transfusion of group O blood to nongroup O recipients constitutes risk that is outweighed by the benefits. A low titer of anti-A/B will minimize the risk for a hemolytic reaction, particularly if the screening is repeated after an immunization episode, e.g., blood transfusion, vaccination, or pregnancy.