Encyclopedia of Health and Medicine

128 The Blood and Lymph
blood products used for transfusions. According to
the American Association of Blood Banks, 8 million
Americans donate 15 million units of blood
each year. Because blood banks separate the
majority of donated blood into component blood
products, one unit of donated whole blood can
meet multiple needs.
The body replaces lost fluid volume (PLASMA)
within 24 hours of donation, and erythrocytes
(red blood cells) and other blood cells in six to
eight weeks. A healthy adult may donate one unit
of whole blood every eight weeks. There is no cost
for donating blood, and there is very minimal risk.
A person cannot contract HEPATITIS, HIV/AIDS, or
other infectious diseases through the process of
donating blood.
Donor Requirements
In the United States, individual states and blood
banks establish regulations and procedures to
determine donor eligibility. In general, a prospective
donor must
• be 17 years of age or older
• pass a preliminary health screening that identifies
potential health risks for the donor or for
recipients of the donor’s blood
• weigh 100 pounds or more
Health screening questions aim to reveal
behaviors or practices that carry a risk for INFEC-
TION with diseases such as hepatitis and HIV/AIDS.
Such behaviors include intravenous DRUG use and
sex with multiple partners. In 1998, US blood
banks also began screening prospective donors for
possible exposure to variant Creutzfeldt-Jakob disease
(VCJD), the human illness resulting from
bovine spongiform encephalopathy (“mad cow”
disease). Numerous health conditions may preclude
an individual from donating blood; blood
banks refer to these exclusions as deferrals.
The Blood Donation Procedure
The total blood donation process takes about 45
minutes to an hour, about 20 minutes of which is
the actual blood withdrawal (called PHLEBOTOMY).
Once the prospective donor clears the health
screening, he or she sits in a reclining chair to be
comfortable for the donation process. The technician
cleanses the inner arm at the elbow with an
antiseptic and puts a tourniquet briefly around the
upper arm to cause the veins to engorge. The
technician then inserts a sterile needle, connected
to collection tubing and bag, into one of the veins
and releases the tourniquet.
The technician may ask the person to periodically
squeeze an object to help move blood
through the VEIN during collection. After blood fills
the collection bag (one unit), the technician withdraws
the needle and places pressure over the
puncture site for several minutes to suppress any
bleeding, then applies a bandage that should stay
in place for two to four hours. The person moves
to a resting area, usually to have a drink of juice
or water and a snack, then may leave when he or
she feels comfortable. The risks associated with
donating blood are very minor and may include
bleeding, bruising, or discomfort at the needle
insertion site.
Donor Blood Distribution and Use
Most donated blood goes to centralized blood
banks for distribution to hospitals, which administer
it to anyone who needs it. Two exceptions are
• autologous donation (BLOOD AUTODONATION), in
which an individual donates blood for his or
her own transfusion such as for a planned
major surgery
• directed donation, in which an individual asks
that others donate blood on his or her behalf
and specified use, such as following a major
trauma or unanticipated major surgery
Blood banks generally cannot use blood not
used for self-transfusion (autologous donation) or
not administered to the intended recipient
(directed donation) for general transfusions and
must instead throw it away. Some blood banks
screen and process autologous donations differently
from general donations, making autologous
donations unacceptable for general use. Other
blood banks handle autologous and general donations
the same and have procedures for donors to
authorize, at the time of donation, other use of
their blood under such circumstances to avoid
unnecessary waste of such a valuable resource.
Though blood banks screen and process directed