Blood collection

[Michiko]

More than 21 million units of blood components are transfused yearly in the US, from about 7 million volunteer donors (1). Although transfusion is probably safer than ever, risk (and the public’s perception of risk) mandates informed consent whenever practical.
In the US, the collection, storage, and transport of blood and its components are standardized and regulated by the FDA, the AABB (formerly known as the American Association of Blood Banks), and sometimes by state or local health authorities. Donor screening includes an extensive questionnaire and health interview; measurement of temperature, heart rate, and blood pressure; and Hb determination. Some potential donors are deferred either temporarily or permanently (see table Some Reasons for Blood Donation Deferral or Denial). Criteria for deferral protect prospective donors from possible ill effects of donation and recipients from disease.
Whole blood donations are limited to once every 56 days, whereas apheresis red blood cell (RBC) donations (donations of twice the usual amount of RBCs in one sitting, with the separated plasma being returned to the donor) are limited to once every 112 days. Apheresis platelet donations are limited to once every 72 hours with a maximum of 24/year. With rare exceptions, blood donors are unpaid. (See also the American Red Cross for information regarding donor eligibility.)
In standard blood donation, about 450 mL of whole blood is collected in a plastic bag containing an anticoagulant preservative. Whole blood or packed RBCs preserved with citrate-phosphate-dextrose-adenine may be stored for 35 days. Packed RBCs may be stored for 42 days if an adenine-dextrose-saline solution is added.
Autologous donation, which is use of the patient’s own blood, is less preferred as a method of transfusion. When done before elective surgery, up to 3 or 4 units of whole blood or packed RBCs are collected in the 2 to 3 weeks preceding surgery. The patient is then given iron supplements. Such elective autologous donation may be considered when matched blood is difficult to obtain because the patient has made antibodies to red cell antigens or has a rare blood type. Special blood salvage procedures are also available for collecting and autotransfusing blood shed after trauma and during surgery.