[Blood transfusion security: one train may conceal another!]. / Sécurité transfusionnelle: un train peut en cacher un autre!

The discovery of antibodies with specificities that are directed toward antigens of high prevalence is a difficult situation to manage in emergency blood transfusion. The reactions they produce interfere with the identification of reactions due to other, clinically significant antibodies. We report a case which illustrates this problem in terms of transfusion safety and time to carry out the tests.