Cryoprecipitate

Cryoprecipitate, formally "Cryoprecipitated AHF" and commonly called "cryo" is a frozen blood product prepared from plasma. Each 15 mL unit typically contains 100 IU of factor VIII, and 250 mg of fibrinogen. It also contains von Willebrand factor (vWF), factor XIII, and fibronectin. It is often transfused as a four to six unit pool instead of as a single product. The AHF stands for antihemophyllic factor, which is an anachronism since Cryo is no longer the therapy of choice for these patients. Many uses of the product have replaced by factor concentrates, but it is still routinely stocked by many hospital blood banks.

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US standards require manufacturers to test at least four units each month, and the products must have an average of 150 mg or more of fibrinogen and 80 IU of factor VIII. Individual products may actually have less than these amounts as long as the average remains above these minimums. Typical values for a unit are substantially higher, and aside from infants it is rare to transfuse just one unit.

Like FFP, compatibility testing is not indicated, but it is given as ABO compatible. Compatibility is reversed for plasma products: AB is the universal donor type and O is the universal recipient.

Indications for giving cryoprecipitate include:

• Haemophilia- Used for emergency back up when factor concentrates are not available.
• von Willebrands's disease- As with other forms of haemophilia, factor concentrates are the therapy of choice.
• hypofibrinogenaemia (low fibrinogen levels), as can occur with massive transfusions
• bleeding from excessive anticoagulation- Fresh frozen plasma contains most of the coagulation factors, and is a much better choice when anticoagulation has to be quickly reversed.
• massive haemorrhage- RBCs and volume expanders are preferred therapies.
• disseminated intravascular coagulation

The product is manufactured by slowly thawing a unit of FFP at temperatures just above freezing, typically in a water bath or a refrigerator. The product is then centrifuged to remove the majority of the plasma and the precipitate is resuspended in the remaining plasma or in sterile saline. The product may then be pooled and frozen or frozen as individual units.

References

1. Erber WN, Perry DJ (2006) Plasma and plasma products in the treatment of massive haemorrhage. Best Pract Res Clin Haematol 19(1):97-112. PMID 16377544
2. Circular of Information, the US standards for blood products.