2. Is the autologous control negative or positive?

• Autologous Control- the patient’s RBCs tested against the patient’s serum or plasma in the same manner as the antibody screen • (+) Ab screen and (-) Autologous control  Alloantibody detected • (+) Autologous control- may be caused by alloantibody coating circulating donor RBCs.  Autoantibody detected due to: Recent Transfusion in the previous 3 months  Require time and experience