Which patient is considered a universal donor

Blood types are determined by the presence or absence of certain antigens — substances that can trigger an immune response if they are foreign to the body. Since some antigens can trigger a patient's immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching. Do you know what blood type is safe for you if you need a transfusion?

There are four major blood groups determined by the presence or absence of two antigens — A and B — on the surface of red blood cells. There are very specific ways in which blood types must be matched for a safe transfusion. The right blood transfusion can mean the difference between life and death.

Also, Rh-negative blood is given to Rh-negative patients, and Rh-positive or Rh-negative blood may be given to Rh-positive patients. The rules for plasma are the reverse. There are more than other known antigens, the presence or absence of which creates "rare blood types.

Learn about blood and diversity. Universal donors are those with an O negative blood type. O negative blood can be used in transfusions for any blood type. O- blood is the blood type in the highest demand. O- blood is the preferred blood type for people with underdeveloped immune systems, including premature babies and cancer patients.

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Popular Articles. What Makes Blood Types Rare? We use cookies to provide and improve our services. By using our site, you consent to cookies. If your blood has the B antigen but not the Rh antigen, your blood type is B-negative B—. Rh blood type is even more important for pregnant women. A problem can occur when a woman who has Rh-negative blood becomes pregnant with a baby fetus that has Rh-positive blood.

This is called Rh incompatibility. If the blood of an Rh-positive baby mixes with the blood of an Rh-negative mother during pregnancy or delivery, the mother's immune system makes antibodies. This antibody response is called Rh sensitization and, depending on when it occurs, can destroy the baby's red blood cells. Rh sensitization does not generally affect the health of the baby during the pregnancy in which the sensitization occurs. But the health of a baby with Rh-positive blood during a future pregnancy is more likely to be affected.

After sensitization has occurred, the baby can develop mild to severe problems called Rh disease or erythroblastosis fetalis. In rare cases, if Rh disease is not treated, the baby may die. An Rh test is done in early pregnancy to check a woman's blood type. If she is Rh-negative, she can get a shot of Rh immunoglobulin that almost always prevents sensitization from occurring. Problems from Rh sensitization have become very rare since Rh immunoglobulin was developed.

In general, there's nothing you have to do before this test, unless your doctor tells you to. A health professional uses a needle to take a blood sample, usually from the arm. When a blood sample is taken, you may feel nothing at all from the needle.

Or you might feel a quick sting or pinch. There is very little chance of having a problem from this test. When a blood sample is taken, a small bruise may form at the site.

The following table shows the compatibility of blood types between blood donors and recipients. Read the table as follows: A person who has A-negative blood can receive A-negative or O-negative blood.

Minor antigens other than A, B, and Rh on the red blood cells are also checked for a match before a blood transfusion. Gabica MD - Family Medicine. Author: Healthwise Staff. Medical Review: E. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.