Given the possibility of infectious transmission (hepatitis, AIDS, etc), blood products are given only if absolutely necessary. The decision to give blood is determined by many factors. A young healthy person is able to tolerate anemia (decreased blood counts) better than an elderly person with heart disease. We would therefore allow the healthy patient to loose more blood before transfusing. We can follow the blood counts during surgery to help us decide when to transfuse. The possibility of transfusion is higher in procedures that might involve significant blood loss such as spine fusion and open heart surgery. Techniques such as recycling your blood (cell saver) and pre -donation of your blood before surgery reduce the possibility of foreign blood transfusion.