Before you receive a blood transfusion, your blood is tested to determine your blood type. Blood or blood components that are compatible with your blood type are ordered by the doctor. This blood may be retested in the hospital laboratory to confirm its type. A sample of your blood is then mixed with a sample of the blood you will receive to check that no problems result, such as red blood cell destruction (hemolysis) or clotting. This process of checking blood types and mixing samples of the two blood sources is called typing and crossmatching.

Before actually giving you the transfusion, the doctor and nurses will each examine the label on the package of blood and compare it to your blood type as listed on your medical record. Only when all agree that this is the correct blood and that you are the correct recipient will the transfusion begin. Giving you the wrong blood type can result in a mild to serious transfusion reaction.

If you have banked your own blood in preparation for surgery (autologous donation), typing and crossmatching is not needed, but the doctors and nurses still examine the label to confirm that it is the blood you donated and that you are the right recipient. For more information on this option, see:

Should I bank blood before having surgery?

Sometimes a doctor will recommend that you take acetaminophen (such as Tylenol), antihistamines (such as Benadryl), or other medicines to help prevent mild reactions, like a fever or hives, from a blood transfusion. Your doctor can treat more severe reactions as they occur.

To receive the transfusion, you will have an intravenous (IV) catheter inserted into a vein. A tube connects the catheter to the bag containing the transfusion, which is placed higher than your body. The transfusion then flows slowly into your vein. A doctor or nurse will check you several times during the transfusion to watch for a transfusion reaction or other problem.