Abstract
Group O Rh-negative blood (500 cc) was transfused without cross-matching to a 9-year-old Group A2. Rh-positive child as emergency therapy in the course of nephrectomy for traumatic rupture of the kidney. The patient made a complete recovery. The donor''s blood, which was not screened for its anti-A and anti-B agglutinin and hemolysin activity, proved to be "dangerous universal donor" blood by a variety of serological tests. The fact that the recipient was sub-group A2 was considered important in the mildness of the hemolytic reactions. The therapy of "dangerous donor" transfusion reaction is discussed. Importance of screening "universal donor" blood for its antibody titers is stressed.