[Correct preparation of a transfusion: Part 1].

The administration of blood products is strictly regulated. Several weeks before the operation the preparation for transfusion begins with optimizing the patient's hematological and hemostaseological situation. In elective surgery blood group testing and antibody screening are performed soon after admission of the patient. The identification of the blood sample is important. Informed consent of the recipient has to be obtained. On the day before the operation a further blood sample is necessary for cross-matching if red blood cells are to be transfused. Usually blood products are issued for immediate administration. Before transfusion begins the blood product has to be checked, the identity of the patient must be controlled and in the case of red blood cell transfusions the AB0 bedside test has to be performed.