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Whole blood is a term used in transfusion medicine for human blood from a standard blood donation. The blood is typically combined with an anticoagulant during the collection process, but is generally otherwise unprocessed. In the US, the capitalized "Whole Blood" means a specific standardized product for transfusion or further processing, where "whole blood" is any unmodified collected blood.
Historically, blood was transfused as whole blood without further processing. Most blood banks now split the whole blood into two or more components, typically red blood cells and a plasma component such as Fresh Frozen Plasma. Platelets for transfusion can also be prepared from a unit of whole blood. Some blood banks have replaced this with platelets collected by plateletpheresis because whole blood platelets, sometimes called "random" platelets, must be pooled from multiple donors to get enough for a therapeutic dose.
The collected blood is generally separated into components by one of three methods. A centrifuge can be used in a "hard spin" which separates whole blood into plasma and red cells or for a "soft spin" which separates it into plasma, buffy coat (used to make platelets), and red blood cells. The third method is sedimentation: the blood simply sits overnight and the red cells and plasma are separated by gravitational interactions.
Whole blood has similar risks to a transfusion of red blood cells and must be cross-matched to avoid hemolytic transfusion reactions. Most of the indications for use are identical to those for RBCs, and whole blood is not used because the extra plasma can contribute to transfusion associated circulatory overload (TACO), a potentially dangerous complication.
Whole blood is sometimes "recreated" from stored red blood cells and fresh frozen plasma (FFP) for neonatal transfusions. This is done to provide a final product with a very specific hematocrit (percentage of red cells) with type O red cells and type AB plasma to minimize the chance of complications.
Whole blood is typically stored under the same conditions as red blood cells and can be kept up to 35 days if collected with CPDA-1 storage solution or 21 days with other common storage solutions such as CPD.
If the blood will be used to make platelets, it is kept at room temperature until the process is complete. This must be done quickly to minimize the warm storage of RBCs in the unit.