Blood is classified into four different types: A, B, AB, and O.
Another way blood cells may be classified is by Rh factors. People who have Rh factors in their blood are called "Rh positive." People without these factors are called "Rh negative." Rh negative people form antibodies against Rh factor if they receive Rh positive blood.
There are also other factors to identify blood cells, in addition to ABO and Rh.
Your immune system can usually tell its own blood cells from those of another person. If you receive blood that is not compatible with your blood, your body produces antibodies to destroy the donor's blood cells. This process causes the transfusion reaction. Blood that you receive in a transfusion must be compatible with your own blood. This means that your body does not have antibodies against the blood you receive.
Most of the time, a blood transfusion between compatible groups (such as O+ to O+) does not cause a problem. Blood transfusions between incompatible groups (such as A+ to O-) cause an immune response. This can lead to a serious transfusion reaction. The immune system attacks the donated blood cells, causing them to burst.
Today, all blood is carefully screened. Transfusion reactions are rare.
A hemolytic transfusion reaction is a serious complication that can occur after a blood transfusion. The reaction occurs when the red blood cells that were given during the transfusion are destroyed by the person's immune system.
There are other types of allergic transfusion reactions that do not cause hemolysis.
Exams and Tests
This disease may change the results of these tests:
Outcome depends on how bad the reaction is. The disorder may disappear without problems. Or, it may be severe and life threatening.
Donated blood is put into ABO and Rh groups to reduce the risk of transfusion reaction.
Before a transfusion, recipient and donor blood are tested (cross-matched) to see if they are compatible. A small amount of donor blood is mixed with a small amount of recipient blood. The mixture is checked under a microscope for signs of antibody reaction.
Before the transfusion, your provider will usually check again to make sure you are receiving the right blood.
Symptoms may include any of the following:
Symptoms of a hemolytic transfusion reaction most often appear during or right after the transfusion. Sometimes, they may develop after several days (delayed reaction).
If symptoms occur during the transfusion, the transfusion must be stopped right away. Blood samples from the recipient (person getting the transfusion) and from the donor may be tested to tell whether symptoms are being caused by a transfusion reaction.
Mild symptoms may be treated with:
- Acetaminophen, a pain reliever to reduce fever and discomfort
- Fluids given through a vein (intravenous) and other medicines to treat or prevent kidney failure and shock
When to Contact a Medical Professional
Tell your health care provider if you are having a blood transfusion and you have had a reaction before.
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Goodnough L. Transfusion medicine. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 177.
Hall JE. Blood types; transfusion; tissue and organ transplantation. In: Hall JE, ed. Guyton and Hall Textbook of Medical Physiology. 13th ed. Philadelphia, PA: Elsevier; 2016:chap 36.