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Blood transfusion is
a medical treatment that replaces blood lost through injury, surgery, or
disease. The blood goes through a tube from a bag to an intravenous (IV)
catheter and into your vein.
You may need a
blood transfusion if you lose too much blood, such as through:
If you have an illness in which your
bone marrow doesn't make enough blood, such as
aplastic anemia, you may need transfusions.
Blood used for
transfusions in the United States is very safe and generally free from disease.
Donated blood is carefully tested. It is very rare to get a disease through a
Getting the wrong blood type by accident is the
main risk in a blood transfusion, but it is rare. Getting the wrong blood type
happens in about 1 out of 14,000 transfusions.1
Transfusion with the wrong blood type can cause a severe reaction that may be
life-threatening, but this is very rare.2
Some people bank their own blood a few weeks
before they have surgery. If they need a transfusion during surgery, they can
receive their own banked blood. This reduces the risk of disease and
transfusion reaction from donated blood.
If you have many blood
transfusions, you are more likely to have problems from
immune system reactions. A reaction happens when your
body rejects the new blood and tries to attack parts of it. But tests can help
avoid this. Before you get a blood transfusion, your blood is tested to find
out your blood type. And the blood you will get in the transfusion is tested to
make sure it matches your blood.
You may have a mild allergic
reaction even if you get the correct blood type. Signs of a reaction
A mild reaction can be scary, but it rarely is dangerous
if it's treated quickly.
The most important blood type classification systems are the ABO system and the
Rh system. A, B, AB, and O are the
blood types in the ABO system. Each type of blood in
the ABO system also has a positive or negative
Rh factor. For example, if you have "A+ blood," it
means your blood is type A in the ABO system and your Rh factor is
If you get blood in a transfusion that isn't the right
type, you may have a transfusion reaction. A mild transfusion reaction rarely
is dangerous, but you must get treatment quickly. A severe transfusion reaction
can be deadly.
Blood banks collect blood
from volunteer donors. Before they donate, volunteers must answer questions
about their current health, health history, and any diseases they may have been
exposed to through travel to foreign countries, sexual behavior, or drug use.
Only people who pass this survey are allowed to donate blood.
Donated blood is then carefully tested for certain diseases and to find
out the blood type. If there is any chance that the blood may not be safe to
use, it is thrown away.
Most blood that passes the tests is then
split into its components and sent out for use.
Blood and its
components can be stored or used for only a short time before they must be
thrown away. This is why blood banks are always looking for donors.
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Learning about blood transfusions:
are used to treat blood loss or to supply blood components that your body
cannot make for itself.
Blood loss may result from
injury, major surgery, or diseases that destroy
red blood cells or
platelets, two important blood components. If too much
blood is lost (low blood volume), your body cannot maintain a proper blood
pressure, which results in
shock. Blood loss can also reduce the number of
oxygen-carrying red blood cells in the blood, which may prevent enough oxygen
from reaching the rest of the body.
Whole blood is rarely given
to treat blood loss. Instead, you are given the blood component you most need.
If you have lost too many red blood cells or are not making enough of them, you
are given packed red blood cells. If you have low blood volume, you are given
plasma and/or other fluids to maintain blood pressure.
If you have lost a great deal of blood, or if your
clotting factors or platelets are low or abnormal, you
may also need a transfusion of either of these to help control bleeding.
Sometimes you may need replacements of some blood substances if your body does
not make enough of them. For example, you may be given substances to help your
blood clot (clotting factors) if you do not have enough of them
Blood lost during surgery sometimes can be recovered,
cleaned, and returned to you as a transfusion. This greatly reduces the amount
of blood you might otherwise need to receive. Receiving your own blood back is
safer, because there is no chance of a reaction.
component that affects the blood's ability to clot is platelets. A reduced
number of platelets (thrombocytopenia) or the failure of
platelets to function properly increases the time it takes for bleeding to stop
(increased bleeding time). Transfusion with platelets improves the clotting
time, which reduces the risk of uncontrolled bleeding. This treatment does not cure
the cause of platelet loss.
Anemia is a
decrease in the number of oxygen-carrying red blood cells or a decrease in the
hemoglobin, the oxygen-carrying substance in the red
blood cells. There are several types of anemia, each with a different cause,
and each is treated differently. Severe anemia may be treated with a
transfusion of packed red blood cells. This temporarily increases the
number of oxygen-carrying red blood cells in circulation and may improve
symptoms, but it does not treat the cause of the anemia.
Almost all of the blood used for blood transfusions is donated by volunteers.
For details on the donation process, see Donating Blood.
The process of blood donation and the handling of donated
blood in the United States is regulated by the U.S. Food and Drug
Administration (FDA). The FDA enforces five layers of overlapping safeguards to
protect the blood supply against disease.
If you are going
to have surgery and expect to need a
blood transfusion, you may want to consider donating
or banking your own blood before the surgery (autologous donation).
For more information on this option, see:
Your blood is
typed, or classified, according to the presence or
absence of certain markers (antigens) found on red blood cells and
in the plasma that allow your body to recognize blood as its own. If another
blood type is introduced, your
immune system recognizes it as foreign and attacks it,
resulting in a
The ABO system consists of
A, B, AB, and O blood types. People with type A have
antibodies in the blood against type B. People with
type B have antibodies in the blood against type A. People with AB have no
anti-A or anti-B antibodies. People with type O have both anti-A and anti-B
antibodies. People with type AB blood are called universal recipients, because
they can receive any of the ABO types. People with type O blood are called
universal donors, because their blood can be given to people with any of the
ABO types. Mismatches with the ABO and Rh blood types are responsible for the
most serious, sometimes life-threatening, transfusion reactions.
The Rh system classifies blood as
Rh-positive or Rh-negative, based on the presence or absence of Rh antibodies
in the blood. People with Rh-positive blood can receive Rh-negative blood, but
people with Rh-negative blood will have a transfusion reaction if they receive
Rh-positive blood. Transfusion reactions caused by mismatched Rh blood types
can be serious.
There are over 100 other blood
subtypes. Most have little or no effect on blood transfusions, but a few of
them may be the main causes of mild transfusion reactions. Mild transfusion
reactions are frightening, but they are rarely life-threatening when treated
The risks of
blood transfusions include
transfusion reactions (immune-related reactions),
nonimmune reactions, and infections.
occur when your immune system attacks components of the blood being transfused
or when the blood causes an
allergic reaction. This is called a transfusion reaction.
reactions occur because of errors made in matching the recipient's blood to the
blood transfused. These administrative errors may occur because of mislabeled
blood samples or misread labels. Much effort is made to prevent these errors;
they occur in about 1 out of 14,000 transfusions.1
Even receiving the correct blood type sometimes results in a mild transfusion
These reactions may be mild or severe. Most mild
reactions are not life-threatening when treated quickly. Even mild reactions,
though, can be frightening. Severe transfusion reactions can be
life-threatening, but this is very rare.2
Mild allergic reactions may involve itching, hives,
wheezing, and fever. Severe reactions may cause
Doctors will stop a blood transfusion if they think you are having a
reaction. A reaction may turn out to be mild. But at the beginning, it is hard
for doctors to know whether it will be severe.
There are several immune-related transfusion
Fluid overload is a common
type of nonimmune reaction.
Very rarely, a person can develop iron overload after
having many repeated blood transfusions. This condition, sometimes called
hemochromatosis, is often treated with medicine. Too
much iron can have an effect on many organs in the body.
The transmission of viral infections,
hepatitis B or C or
HIV, through blood transfusions has become very rare
because of the safeguards enforced by the U.S. Food and Drug Administration
(FDA) on the collection, testing, storage, and use of blood. The risk of
infection from a blood transfusion is higher in less developed countries, where
such testing may not happen and paid donors are used.
possible for blood to be contaminated with bacteria
or parasites. Bacterial contamination can happen during or after donation. Donated blood might have a parasitic infection. Transfusion with blood that has bacteria or parasites can result
in a systemic infection. But this risk is small.
The risk of a bacterial infection in donated blood is small because of the precautions taken in drawing
and handling blood. There is a greater risk of
bacterial infection from transfusions with platelets. Unlike most other blood
components, platelets are stored at room temperature. If any bacteria are
present, they will grow and cause an infection when the platelets are used for
Before you receive a
blood transfusion, your blood is tested to
determine your blood type. Blood or blood components
that are compatible with your
blood type are ordered by the doctor. This blood may
be retested in the hospital laboratory to confirm its type. A sample of your
blood is then mixed with a sample of the blood you will receive to check that
no problems result, such as red blood cell destruction (hemolysis) or clotting.
This process of checking blood types and mixing samples of the two blood
sources is called typing and crossmatching.
Before actually giving
you the transfusion, a doctor or nurse will examine the label on the
package of blood and compare it to your blood type as listed on your medical
record. Only when all agree that this is the correct blood and that you are the
correct recipient will the transfusion begin. Giving you the wrong blood type
can result in a mild to serious
If you have banked
your own blood in preparation for surgery (autologous donation), typing and
crossmatching is not needed. But the doctors and nurses still examine the label
to confirm that it is the blood you donated and that you are the right
recipient. For more information on this option, see:
Sometimes a doctor will recommend that you take
acetaminophen (such as Tylenol),
antihistamines (such as Benadryl), or other medicines
to help prevent mild reactions, like a fever or
hives, from a blood transfusion. Your doctor can treat
more severe reactions as they occur.
To receive the transfusion,
you will have an intravenous (IV) catheter inserted into a vein. A tube
connects the catheter to the bag containing the transfusion, which is placed
higher than your body. The transfusion then flows slowly into your vein. A
doctor or nurse will check you several times during the transfusion to watch
for a transfusion reaction or other problem.
Experts are trying to create artificial blood or blood replacements. Blood replacements being
studied include oxygen-carrying chemicals (such as perfluorocarbon emulsions)
hemoglobin—the portion of the red blood cell that
carries oxygen. There are several advantages to blood replacements.
The blood replacement products being tested still have
problems. For example, blood replacement products can interfere with blood
tests, are more quickly removed from the body, and are less efficient oxygen
Several of these products are being developed. But their
use, after they are approved, will probably be limited to emergencies involving
severe blood loss caused by serious accidents.
The American Cancer Society (ACS) conducts educational
programs and offers many services to people with cancer and to their families.
Staff at the toll-free number have information about services and activities
in local areas and can provide referrals to local ACS divisions.
This Web site has news on what the American Red Cross
is doing in America and around the world. It also has information on disaster
services (for making donations), Red Cross projects, how to volunteer, and
where you can donate time, money, or blood.
The American Red Cross
is one of America's main emergency response groups. It also offers many other
services, such as community services for the needy, support for military
members and their families, and educational programs that promote health and
safety. But the Red Cross is probably best known for its blood drives and
international relief programs.
The American Red Cross is also part
of a worldwide effort that provides care to the victims of war or natural
disasters. This group always aims to prevent and relieve suffering. The Red
Cross is not a government agency. And it relies on donations of time, money,
and blood to do its work.
America's Blood Centers is a network of nonprofit community blood centers in the United States and Canada. The website can help you find a donor center near you. The donor centers are licensed and regulated by the U.S. Food and Drug Administration and Health Canada. There are more than 600 donor centers.
This website is sponsored by the Nemours Foundation. It
has a wide range of information about children's health—from allergies and
diseases to normal growth and development (birth to adolescence). This website
offers separate areas for kids, teens, and parents, each providing
age-appropriate information that the child or parent can understand. You can
sign up to get weekly emails about your area of interest.
The U.S. National Heart, Lung, and Blood Institute
(NHLBI) information center offers information and publications about preventing
CitationsGoodnough LT, et al. (2003). Transfusion medicine: Looking to the future. Lancet, 361(9352): 161–169.Galel SA, et al. (2009). Transfusion Medicine. In JP Greer et al., eds., Wintrobe's Clinical Hematology, 12th ed., vol. 1, pp. 672–721. Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedDzieczkowski JS, Anderson KC (2008). Transfusion biology and therapy. In AS Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 1., pp. 707–713. New York: McGraw-Hill Medical.Galel SA, et al. (2009). Transfusion Medicine. In JP Greer et al., eds., Wintrobe's Clinical Hematology, 12th ed., vol. 1, pp. 672–721. Philadelphia: Lippincott Williams and Wilkins.Goodnough LT (2012). Transfusion medicine. In L Goldman, A Shafer, eds., Goldman's Cecil Medicine, 24th ed., pp. 1154–1158. Philadelphia: Saunders.Klein HG (2011). Transfusion medicine. In EG Nabel, ed., ACP Medicine, section 5, chap. 10. Hamilton, ON: BC DeckerMcCullough J (2010). Blood procurement and screening. In K Kaushanksy et al., eds., Williams Hematology, 8th ed., pp. 2279–2286. New York: McGraw-Hill.Murphy M, Vassallo R (2010). Preservation and clinical use of platelets. In K Kaushanksy et al., eds., Williams Hematology, 8th ed., pp. 2301–2315. New York: McGraw-Hill.
October 27, 2011
E. Gregory Thompson, MD - Internal Medicine & Brian Leber, MDCM, FRCPC - Hematology
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