A blood bank is a cache or bank of blood or blood components, gathered as a result of blood donation, stored and preserved for later use in blood transfusions.

An early development leading to the establishment of blood banks occurred in 1915, when Richard Lewisohn of Mount Sinai Hospital, New York initiated the use of sodium citrate as an anticoagulant. This discovery transformed the blood transfusion procedure from direct (vein-to-vein) to indirect. In the same year, Richard Weil demonstrated the feasibility of refrigerated storage of anticoagulated blood. The introduction of a citrate-glucose solution by Francis Peyton Rous and JR Turner two years later permitted storage of blood in containers for several days, thus opening the way for the first "blood depot" established in Britain during World War I. Oswald Robertson, a U.S. Army officer who established the depots, is now recognized as the creator of the first blood bank.

By the mid-1930s, the Soviet Union had set up a system of at least sixty large blood centers and more than 500 subsidiary ones, all storing "canned" blood and shipping it to all corners of the country. News of the Soviet experience traveled to America, where in 1937 Bernard Fantus, director of therapeutics at the Cook County Hospital in Chicago, established the first hospital blood bank in the United States. In creating a hospital laboratory that preserved and stored donor blood, Fantus originated the term "blood bank." Within a few years, hospital and community blood banks were established across the United States.

An important breakthrough came in 1939-40 when Karl Landsteiner, Alex Wiener, Philip Levine, and R.E. Stetson discovered the Rh blood group system, which was found to be the cause of the majority of transfusion reactions up to that time. Three years later, the introduction by J.F. Loutit and Patrick L. Mollison of acid citrate dextrose (ACD) solution, which reduces the volume of anticoagulant, permitted transfusions of greater volumes of blood and allowed longer term storage.

Carl Walter and W.P. Murphy, Jr., introduced the plastic bag for blood collection in 1950. Replacing breakable glass bottles with durable plastic bags allowed for the evolution of a collection system capable of safe and easy preparation of multiple blood components from a single unit of whole blood.

Further extending the shelf life of stored blood was an anticoagulant preservative, CPDA_1, introduced in 1979. It increased the blood supply and facilitated resource sharing among blood banks.

Donated blood only lasts 35_42 days. Platelets, which contain clotting agents, last only 5 days.[1] (http://www.healthdistrict.org/HWlibrary/bloodbank.htm)

See also: autologous donation, phlebotomist