by William Crews, MD
Cryoprecipitated Antihemophilic Factor is more commonly known as cryoprecipitate, or simply cryo. Cryoprecipitate can only be made from Fresh Frozen Plasma (FFP), which has been removed from whole blood and frozen within eight hours of being collected. The FFP is slowly thawed between 1 and 6C. This results in a supernatant that includes proteins that have gone back into solution, and a precipitated component consisting of cold-insoluble proteins. After thawing is complete the unit is centrifuged, the supernatant is removed, leaving behind the cryoprecipitate plus 5 to 15 mL of plasma. The cryoprecipitate is refrozen within 1 hour of thawing and stored at -18C or colder, and has a shelf life of 12 months.
Cryoprecipitate contains mostly fibrinogen (factor I) and factor VIII, but also contains (smaller amounts of) factor XIII, von Willebrand factor (VWF), and fibronectin. A single unit of cryo typically has a volume between 10 to 15 mL. As a convenience to transfusion services, the majority of the cryo we manufacture is pre-pooled frozen cryo. We pool together 5 single units of cryo with the same ABO type into a single bag of pooled cryo. The volume of pooled cryo generally ranges from 95 – 130mL.
AABB standards require each unit of cryo contain a minimum of 150mg of fibrinogen and 80 IU of factor VIII.
Historically, cryo was used to treat congenital factor VIII deficiency (Hemophilia A) and von Willebrand disease. Due to the development of virus-inactivated Factor VIII concentrates and recombinant factor preparations, cryo is no longer considered first-line therapy for these diseases. Today the most common indication for cryoprecipitate is replacement of fibrinogen in patients with acquired hypofibrinogenemia and bleeding, usually in the setting of surgical bleeding or trauma.
In the average patient, each unit raises the plasma fibrinogen concentration by at least 7 to 10 mg/dL; thus, 10 units will raise the fibrinogen by approximately 70 to 100 mg/dL in a 70 kg recipient.
ABO-compatible cryoprecipitate is NOT required due to the small volume of plasma transfused, although this may be important in patients receiving large volumes of cryo relative to their red blood cell mass. Rh compatibility need not be considered when selecting this product for transfusion and cross matching is not necessary.