blood disorders
Blood Products
Red blood cells
 Packed red blood cells, the most commonly transfused blood component, can restore the blood's oxygen-carrying capacity. This component may be given to a person who is bleeding or who has severe Overview of Anemia . The red blood cells are separated from the fluid component of the blood (plasma) and from the other cellular components. This step concentrates the red blood cells so that they occupy less space, thus the term “packed.” Sometimes red blood cells are specially prepared (washed) so they can be given to people who have had severe reactions to plasma. Washed red blood cells are free of almost all traces of plasma, most white blood cells, and platelets. Special filters are routinely used to remove white blood cells to reduce many types of side effects, including fever, chills, Cytomegalovirus (CMV) Infection , and antibody formation against human leukocyte antigens (HLA). HLA antigens are chemical markers located on the surface of cells and are unique in each organism, enabling the body to distinguish self from nonself. Red blood cells can be refrigerated for up to 42 days. In special circumstances—for instance, to preserve a rare type of blood—red blood cells can be frozen for up to 10 years. 