Blood Typing - Cholesterol Test Descriptions

Do you know your blood type? The ABO test classifies people's blood into one of four types: A, B, AB, or O. If your red blood cells have:

The A antigen, you have type A blood. The liquid portion of your blood (plasma) contains antibodies against type B blood. The B antigen, you have type B blood. Your plasma contains antibodies against type A blood. Neither the A nor B antigen, you have type O blood. Your plasma contains antibodies against both type A and type B blood. Both the A and B antigens, you have type AB blood. Your plasma does not contain antibodies against either type A or type B blood. Blood received in a transfusion must contain antigens that are the same as the antigens on a person's own red blood cells (compatible blood). If you receive a transfusion that contains antigens different from your own (incompatible blood), the antibodies in your plasma will recognize the transfused (donor) blood as foreign and will attack and destroy the donor red blood cells. This is called a transfusion reaction, and it occurs immediately when incompatible blood is transfused. A transfusion reaction can cause serious illness and even death.

Type O-negative blood does not have any antigens. It is called the "universal donor" type because it is compatible with any blood type. Type AB-positive blood is called the "universal recipient" type because a person who has it can receive blood of any type. Although “universal donor” and “universal recipient” types are occasionally used to classify blood in an emergency, blood typing tests are almost always done to prevent transfusion reactions.

This test also checks for the Rh factor type (positive or negative).

Rh blood typing determines the presence (+) or absence (–) of the Rh antigen (also called the Rh factor). If your red blood cells:

Contain the Rh antigen, your blood is Rh-positive. Do not contain the Rh antigen, your blood is Rh-negative. Contain the A and Rh antigens, your blood type is A-positive (A+). If your blood contains the B antigen but not the Rh antigen, your blood type is B-negative (B–). Rh blood typing is especially important for women who want to have children. A potential problem arises when a woman who has Rh-negative blood becomes pregnant with a fetus that has Rh-positive blood. This is called Rh incompatibility. If the blood of an Rh-positive fetus mixes with the blood of an Rh-negative woman during pregnancy or delivery, the mother's immune system produces antibodies. This antibody response is called Rh sensitization and, depending on when it occurs, can destroy the fetus's red blood cells.