Each year blood donors help to save millions of lives. Individuals who routinely donate blood may not give it a second thought, but this selfless gesture ensures accident victims and others get a helping hand when they need it most. Recipients of blood donations are there for the culmination of a process that begins with generous donors, who may be curious about exactly what happens to their blood after it’s collected.

According to the American Red Cross, donated blood is kept on ice before being taken to a processing center, where information about the donation is scanned into a computer database. Upon arriving at processing centers, donated blood is spun in centrifuges to separate it into transfusable components, including red cells, platelets and plasma. Each component is then packaged as a “unit,” or a standardized amount doctors use when transfusing a patient. Blood donations also are tested at a separate laboratory to establish type and check for infectious diseases. The results of these tests are transferred electronically to the processing center within 24 hours, which underscores the efficiency of the donation process. Any blood that tests positive for disease is discarded and donors are notified. If the blood is deemed suitable for transfusion, it is labeled and stored.

Red cells are stored in refrigerators at 6 degrees C for up to six weeks (42 days), while platelets are stored at room temperature in agitators for up to five days. Plasma can be stored in freezers for up to one year.