Protecting the Blood Supply
Testing Donated Blood
In the blood bank laboratory, certain tests must be performed on all donated blood. This includes typing to determine the donor’s ABO blood group and Rh status as well as several screens to ensure the safety of the blood. Screening is conducted for 1) unexpected red blood cell antibodies that could cause reactions in the recipient (such as those made as a result of a previous transfusion or pregnancy) and 2) current and past transmissible infections; each unit of donated blood is tested for:
Testing for these infectious diseases often is done by antibody screening, such as the HIV antibody test, which looks for the antibodies the body makes in response to the invading virus.
Confirmatory tests also are performed if any test results are positive in order to rule out false positives. Once the testing is completed, those units of blood that are free of infection are made available for transfusion when needed. Those in which infection is detected are discarded, and the donor is notified as well as prohibited from future blood donation.
It also is important to realize that there are some infectious diseases that are not or cannot be tested for at the present time, such as the West Nile virus. The potential for an infectious agent that will not be detected in testing to be present in a donated unit underscores the importance of donors reporting any transmissible infections they have had or may have been exposed to in the past.
Storing Blood Safely
Proper storage of whole blood and blood components is essential.
- Red blood cells must be stored under refrigeration and can be kept for a maximum of 42 days or frozen for up to 10 years.
- Platelets can be stored at room temperature for a maximum of 5 days.
- Fresh frozen plasma can be kept frozen for up to 1 year.
- Cryoprecipitate AHF made from fresh frozen plasma can be stored frozen for up to 1 year.
- Granulocytes (white blood cells) must be transfused within 24 hours of donation.