ABO incompatibility
Key points
- ABO incompatability describes an immune reaction that occurs in the body if two blood samples of different, incompatible ABO types are mixed together.
- The types are defined by molecules on the surface of the blood cells.
- Treatment Treatment involves supportive care with intravenous fluids, antihistamines, steroids, and blood pressure support if necessary.
- This can be a very serious problem which can even result in death.
Definition
ABO incompatability describes an immune reaction that occurs in the body if two blood samples of different, incompatible ABO types are mixed together.
Causes, incidence, and risk factors
A, B, and O are the three major blood types. The types are defined by molecules on the surface of the blood cells. In people of different blood types, these molecules act as antigens - immune-response triggers.
Each person has a combination of two of these surface molecules. Type O refers to a lack of any molecule. So, the resulting types are type A (AA or AO molecules), type B (BB or BO molecules), type AB, or type O.
People of a given type form antibodies against other types. When exposed to another type of blood, a breakdown reaction occurs. This is most relevant when a patient needs a blood transfusion or transplant. The blood types must be matched to avoid a reaction based on ABO incompatibility.
For example, a patient with type A blood will react against type B or type AB blood. Similarly, a patient with type B blood will react against type A or type AB blood, and patients with type O blood will react against type A, type B, or type AB blood.
Because type O signifies a lack of any surface molecules, type O blood does not cause an immune response. This is why type O blood cells can be given to patients of any blood type, and people with type O blood are called "univeral donors." However, people with type O can only receive type O.
Since antibodies are present in the blood plasma - the liquid portion of the blood - plasma transfusions as well as whole blood transfusions must be matched to avoid causing an immune reaction.
Symptoms
The following are symptoms of transfusion reactions:
- fever
- blood in urine
- back pain
- feeling of "impending doom"
- jaundice
Signs and tests
- laboratory testing of patient's blood and transfused blood shows incompatibility
- complete blood count (CBC) shows damaged red blood cells, may also show mild anemia
- bilirubin level is elevated
Treatment
Treatment involves supportive care with intravenous fluids, antihistamines, steroids, and blood pressure support if necessary.
Expectations (prognosis)
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.