How Do Blood Banks Work?

Donations

Blood banks collect, process and distribute blood and blood products. They advertise in the media; solicit volunteers to set up blood drives in offices, at churches and universities and at events; run bloodmobiles; and provide fliers and pamphlets to educate people about blood donation. Unlike blood plasma centers, which pay for their supply, blood banks are donation-based. In different countries, blood banks provide different percentages of blood and blood products. In the United States and Canada, blood banks are responsible for around 99 percent of the blood supply. Many blood banks also take donations of umbilical cords (which contain blood stem cells used in place of bone marrow transplants), and a few offer apheresis, which extracts blood, removes just one component of the blood (such as platelets) and then replaces the blood in the donor's body.

Processing

When blood is donated, it does not go straight to hospitals. First, the blood is typed. It is O, A, B or AB, and it has a positive or negative RH factor. Second, the blood is tested. Sensitive screening tests are conducted for antibodies to hepatitis, HIV and syphilis, and blood banks also run nucleic acid amplification tests to detect new viruses for which the body has not yet manufactured antibodies. For any tests that come back positive, technicians run confirmatory tests. Because donors have been screened, very little donated blood is discarded. Third, the whole blood is usually separated into red blood cells, platelets and plasma.

Distributing

In order to cover their costs (most blood banks are nonprofit), the blood products are sold to hospitals. Patients with anemia or significant bleeding often use transfusions of red blood cells, which may be distributed refrigerated (up to 42 days) or frozen (up to 10 years). In patients with cancer (especially leukemia) or frequent bleeding, hospitals transfuse platelets, which are distributed at room temperature and remain viable for five days. Blood plasma is distributed frozen and can be used for up to a year in patients with low clotting factors.

References

• AABB: Blood FAQ