Since inception, primarily after World War II, blood transfusions have become an integral part of medical practice. If not for the ready availability of blood components, life-saving medical treatments, such as the treatment of serious injuries, organ transplants, bone marrow transplants, complicated surgical procedures and cancer treatment would not be possible. It is estimated that five 5 million recipients are transfused with blood components, including red blood cells, platelets and plasma, in the U.S. annually.

The number of units of blood that may be used for a particular situation can sometimes be unpredictable. A complicated surgical procedure may be started with the anticipated use of a certain number of units; however, complications during the procedure may require the use of five to ten times the number of units anticipated. Therefore, it is imperative that blood be available within very short notice. Similar to the withdrawal of cash from a bank, one can only withdraw cash if sufficient deposits were made in advance. A blood bank must have an adequate supply of blood on hand to meet the demand when patients need it.

Unlike medications that are manufactured, blood components can only be collected from healthy volunteer donors and have a very short shelf life, from five days for platelets, six weeks for red cells and one year for frozen plasma. In addition, when collections are at 100 percent of the planned level nationwide, there is only about a one-week supply in the nation's blood banks. When the donations are even slightly lower, at 95 percent of the planned level, there could be a shortage of some types of blood components. Thus, to ensure an adequate blood supply to meet patient need, it is important that all healthy, eligible people donate blood regularly.