Cryoprecipitate is now a widely available fraction of blood prepared by quickly freezing fresh plasma in a plastic bag and allowing it to thaw slowly at 4 °C. The precipitate that forms while the plasma is thawing in the cold may be separated from the supernatant, refrozen, and stored. Pool and Shannon, 1 in an epic discovery during the early 1960s that revolutionized the care of patients with severe hemophilia A, showed that preparations of cryoprecipitate contained concentrated factor VIII. Since about half the clotting factor from an entire unit of blood was present in an extremely small volume (5 to 15 mL), effective and prolonged replacement therapy could be given to hemophiliacs to treat or prevent spontaneous, traumatic, or surgical bleeding. Pool and Shannon 1 knew from the first that cryoprecipitate contained large amounts of fibrinogen in addition to antihemophilic globulin. However, it was not until several years later