What Is a Blood Bank Test?

Mary McMahon
Mary McMahon

A blood bank test is a screening performed on samples to determine if they are safe for transfusion. Government regulations may mandate some testing for common infectious diseases, and blood banks can add optional screening as well. If the outcome of the test is positive, the facility can run a second screening to confirm. Samples may be discarded either way, and some blood banks have a system to notify donors if they find abnormalities, as a courtesy to people who may not be aware of active infections.

Two packs of O- blood.
Two packs of O- blood.

When people donate blood, technicians may perform a brief initial screening to make sure the blood is suitable, checking for issues like a high white blood cell count indicative of infection. The client also undergoes an oral interview to check for risk factors or exclusions that might lead a blood bank to reject the donation. After the collection process, the blood bank test is used to check for compatibility and any signs of contamination that might make the blood unsafe.

The Rhesus Factor set of blood types.
The Rhesus Factor set of blood types.

Blood banks type donations, checking to see which ABO blood group the sample falls into and also screening for the presence of Rhesus factor, a protein that can cause incompatibility issues. Some run additional tests to check for other blood group incompatibilities involving lesser-known groups. This may be more common in areas where the population is at increased risk for genetic reasons.

A diagram of the composition of the blood.
A diagram of the composition of the blood.

Routine blood bank test procedures usually check for Human Immunodeficiency Virus (HIV), hepatitis, and syphilis. Testing can also identify human T-lymphotropic virus (HTLV), Chagas disease, West Nile virus, and other blood-borne pathogens. Very sensitive screening is also used to identify early signs of infection, when the blood might not carry viral antibodies that a routine screen would pick up, but could show signs of changes. This blood bank test allows a facility to reduce the risk of transfusing infected products.

Blood banks typically screen their samples to see if they are safe for transfusion.
Blood banks typically screen their samples to see if they are safe for transfusion.

Procedures for the blood bank test typically require that any positive result be confirmed before taking action. This reduces the risk of problems caused by false positives. Some banks discard no matter what after receiving a single positive result, but still want a confirmatory test because it can provide information about equipment malfunctions or other issues in the lab. Confirmation can also be used to supply information to a blood donor about abnormalities in a sample, which allows people to seek testing and treatment for infections identified by the blood bank.

When people donate blood, technicians may perform a brief initial screening to make sure the blood is suitable.
When people donate blood, technicians may perform a brief initial screening to make sure the blood is suitable.
A blood bank test can identify if the donor has human T-lymphotropic virus or HTLV.
A blood bank test can identify if the donor has human T-lymphotropic virus or HTLV.
Anyone 17 and older may donate blood, provided that they are healthy and don't meet any exclusion criteria.
Anyone 17 and older may donate blood, provided that they are healthy and don't meet any exclusion criteria.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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