Community Blood Center

In 1901, scientist Karl Landsteiner reported that blood could be classified into "types." By matching these blood types, a successful blood transfusion could be made between a healthy donor and a patient in need of blood. Today, hospital blood banks maintain an assortment of blood products (red blood cells, plasma, platelets, etc) in a variety of blood types.

There are four main blood types: A, B, AB, and O. Each of these blood types is either RH positive (+) or Rh negative (-). So, if someone has type B blood, they have either B+ or B- blood.

The blood type of a patient determines which blood types they are able to receive as a transfusion. The blood type of a blood donor also determines who can receive their blood donation.

People with O- blood are called "universal donors" because any patient can receive O- red blood cells. Hospitals use O- red blood cells to provide emergency care for patients needing immediate transfusions. In addition, hospitals maintain a supply of O- blood for patients with an O- blood type, who can only receive O- red blood cells.

On the other end of the spectrum, very few people can receive AB+ red blood cells. However, people with AB+ blood can receive red blood cell transfusions of any blood type, and are known as "universal recipients." AB blood is special for another reason; plasma donations from people with AB blood can be safely transfused to anyone, so AB donors are "universal plasma donors."

To learn more about the distribution of blood types in America, click here.