What Is a Blood Bank Test?

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.

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.

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.

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.

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.