Reasons and Types of ABO Blood Testing

Submitted on March 27, 2012

Blood Type Test

This test needs to be carried out before a patient gets a blood transfusion. It is also done to check the blood type of a pregnant woman. This blood can be typed with certain markers, which are known as antigens that are on the surface of red blood cells. Blood typing can help doctors understand if two people can be called blood relatives. The Rh antigen and the ABO antigens are the most important ones. There are two blood type tests – the ABO blood typing system and the Rh tests.

Types of Blood

This test proves that most people have one of the four blood types. The four blood types are A, B, AB, or O.

  • If a person's red blood cells have the A antigen, then they have A type of blood, and the plasma of your blood can combat against type B blood.
  • If a person has B antigen, then he has type B blood, and the plasma contains certain antibodies that can fight against type A blood.
  • If you don't have A or B antigen, then your blood type is O. The plasma of this blood type can fight against type B and A blood.
  • And if a person has A and B antigens, then he has AB blood. The plasma of this type of blood does not have antibodies against A or B type of blood.

Why Is The Test Important?

When an ABO blood transfusion is being carried out, the blood that is being transfused must have the same antigens as the patient's. That is known as compatible blood. A patient cannot get blood from a person, who has different antigens in his blood as that will be incompatible blood and the antibodies in the patient's blood will destroy the donor blood cells. Transfusion reaction caused by ABO blood group incompatibility can cause illness and in some cases, even death.

There are no antigens in type O-negative blood, and this is a universal donor blood type because this blood type is compatible with any blood group. AB-positive blood group is the universal recipient because they can get blood from any type.

Minor antigens can also cause problems and need to be checked before a blood transfusion.

Rh Test

This test checks the Rh antigen in the red blood cells. If a patient has the Rh antigen that means that his blood is Rh-positive, while the absence of the antigen means that his blood is Rh-negative.