U.S. medical centers vary widely in the average shelf life of the blood in their blood banks. Trauma and high-volume surgical centers receive the oldest blood from the Red Cross, on the premise that they’ll be likely to transfuse it. All blood banks tend to dispense the oldest units first. This reduces waste of donated blood. In the U.S., the FDA sets the maximum shelf life of stored red cells at 42 days. Other developed countries’ practices are similar.