Blood Diseases

Blood Donations / Blood Banking

What is blood banking?

Blood Types

According to the American Association of Blood Banks, distribution of blood types in the US is the following:

O Rh-positive - 38 percent

A Rh-positive - 34 percent

B RH-positive - 9 percent

O Rh-negative - 7 percent

A Rh-negative - 6 percent

AB Rh-positive - 3 percent

B Rh-negative - 2 percent

AB Rh-negative - 1 percent

Blood banking is the process that takes place in the laboratory to ensure that donated blood, or blood products, are safe before they are used in blood transfusions and other medical procedures. Blood banking includes typing the blood for transfusion and testing for infectious diseases.

Facts about blood banking:
According to the American Association of Blood Banks...

About 40,000 units of red blood cells are needed every day.
The number of blood units donated is about 14 million a year.
There are approximately eight million volunteer blood donors.
About four million patients receive transfusions of blood units each year.
Each unit of blood is broken down into components, such as red blood cells, plasma and platelets.
One unit of whole blood, once its separated, may be transfused to several patients, each with different needs.
Annually, more than 23 million units of blood components are transfused.

Who are the blood donors?

Most blood donors are volunteers. However, sometimes, a patient may want to donate blood a couple of weeks before undergoing surgery, so that his/her blood is available in case of a blood transfusion. Donating blood for yourself is called an autologous donation. Volunteer blood donors must pass certain criteria, including the following:

must be at least 17 years of age
must be in good health
must weigh at least 110 pounds
must pass the physical and health history examination given prior to donation

Some states permit persons younger than 17 years to donate blood, with parental consent.

What tests are performed in blood banking?

A certain set of standard tests are performed in the laboratory once blood is donated, including, but not limited to, the following:

typing: ABO group (blood type)
Rh typing (positive or negative antigen)
screening for any unexpected red blood cell antibodies that may cause problems in the recipient
screening for current or past infections, including the following:
- hepatitis viruses B and C
- human immunodeficiency virus (HIV)
- human T-lymphotrophic viruses (HTLV) I and II
- syphilis
Irradiation to blood cells is performed to disable any T-lymphocytes present in the donated blood. (T-lymphocytes can cause a reaction when transfused, but can also cause what is called "graft-versus-host" problems with repeated exposure to foreign cells.)
"Leukocyte-reduced blood" has been filtered to remove the white blood cells which contain antibodies that can cause fevers in the recipient of the transfusion. (These antibodies, with repeated transfusions, may also increase a recipient's risk of reactions to subsequent transfusions.)

What are the components of blood?

While blood, or one of its components, may be transferred, each component serves many functions, including the following:

red blood cells - carry oxygen to the tissues in the body and are commonly used in the treatment of anemia.
platelets - help the blood to clot and are used in the treatment of leukemia and other forms of cancer.
white blood cells - help to fight infection, and aid in the immune process.
plasma - the watery, liquid part of the blood in which the red blood cells, white blood cells, and platelets are suspended. Plasma is needed to carry the many parts of the blood through the bloodstream. Plasma serves many functions, including the following:
- helps to maintain blood pressure
- provides proteins for blood clotting
- balances the levels of sodium and potassium
cryoprecipitate AHF - a portion of the plasma that contains clotting factors that help to control bleeding.

Albumin, immune globulins, and clotting factor concentrates may also be separated and processed for transfusions.

This page was last updated on: January 28, 2008.

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