Physicians who specialize in blood banking/transfusion medicine are responsible for the maintenance of an adequate blood supply, the safety of blood donors and patient-recipients, and the appropriate use of the blood. Pre-transfusion compatibility testing and antibody testing assure that blood transfusions are as safe as possible. These physicians direct the preparation and safe use of specially prepared blood components, including red blood cells, white blood cells, platelets and plasma constituents, and marrow or stem cells for transplantation.