Autologous blood donation.

Although preoperative autologous blood donation is employed in elective surgery, this is declining because of the increasingly safe allogeneic blood supply. However, it continues to be used because of the public's perception of allogeneic blood risks and increasing blood shortages. Patients may donate a unit of blood (450 +/- 45 ml) as often as twice weekly, up to 72 hours before surgery. Preoperative autologous blood is most beneficial in procedures that cause significant blood loss. It has been determined that preoperative autologous blood donation is poorly cost-effective; the use of this procedure must be based on evidence that it is safe and of value for the patient.