Blood typing is a test that
determines a person’s blood type. The test is essential if you need a blood
transfusion or are planning to donate blood. Not all blood types are
compatible, so it is important to know your blood group. Receiving blood that
is incompatible with your blood type could trigger a dangerous immune response.
Your blood type is determined by
what kind of antigens your red blood cells have on the surface. Antigens are substances
that help your body differentiate between its own cells and foreign,
potentially dangerous ones. If your body thinks a cell is foreign, it will set
out to destroy it.
The ABO blood typing system
groups your blood into one of four categories:
A has the A antigen
B has the B antigen
AB has both A and B antigens
O has neither A nor B antigens
If blood enters your system with
antigens that you don’t have, your body will create antibodies against it.
However, some people can still safely receive blood that isn’t their blood
type. So long as the blood they receive doesn’t have any antigens that mark it
as foreign, their bodies won’t attack it.
In other words, donations work as
- O: Type O individuals can donate blood to
anyone (because their blood has no antigens), but can receive blood only from
other type O individuals (because blood with any antigens is seen as foreign).
- A: Type A individuals can donate to other type
A individuals and type AB individuals. Type A individuals can receive blood
only from other type A individuals and type O individuals.
- B: Type B individuals can donate blood to
other B individuals and AB individuals. Type B individuals can receive blood
only from type B individuals and type O individuals.
- AB: Type AB individuals can give blood only to
other AB individuals, but can receive blood of any type.
Blood types are future organized
by Rh factor:
- Rh+: People with Rh-positive blood have Rh
antigens on the surface of their red blood cells. People with Rh+ blood can
receive Rh+ or Rh- blood.
- Rh-: People with Rh-negative blood do not have
Rh antigens. People with Rh- blood can receive only blood that is also Rh-.
Together, the ABO and Rh grouping
systems yield your complete blood type. There are eight possible types: O+, O-,
A+, A-, B+, B-, AB+, and AB-. While type 0 negative has long been considered a
universal donor, more recent research suggests that additional antibodies are
sometimes present and may cause serious reactions
during a transfusion.
Austrian Karl Landsteiner discovered
blood types in 1901. Before that, blood transfusions were risky and potentially
lethal. Landsteiner made the process much safer, and he was awarded the Nobel
Prize for his work.
Blood Typing Is Done
Blood typing is done prior to a
blood transfusion or when classifying a person’s blood for donation. Blood
typing is a fast and easy way to ensure that you receive the right kind of
blood during surgery or after an injury. If you are given incompatible blood,
it can lead to blood clumping, or agglutination, which can be fatal.
Blood typing is especially
important for pregnant women. If the mother is Rh- and the father is Rh+, the
mother and child will have different blood types. In these cases, the mother
needs to receive a drug called RhoGAM. This drug will keep her body from
attacking the baby’s blood cells if their blood becomes mixed, which often
happens during pregnancy.
Risks of Blood Typing
You will need to have your blood
drawn in order to have it typed. Having your blood drawn carries very minimal
under the skin (hematoma)
- fainting or
- infection at
the puncture site
to Prepare for Blood Typing
No special preparation is needed
for blood typing. If you think you might feel faint during the test, you may
want to have someone else drive you home afterward.
Blood Typing Is Performed
The blood draw can be performed
at a hospital or a clinical laboratory. Your skin will be cleaned before the
test with an antiseptic to help prevent infection. A nurse or technician will
wrap a band around your arm to make your veins more visible. He or she will use
a needle to draw several samples of blood from your arm or hand. After the
draw, gauze and a bandage will be placed over the puncture site.
In order to determine your blood
type, a lab technician will mix your blood sample with antibodies that attack
types A and B blood to see how it reacts. If your blood cells clump together
when mixed with antibodies against type A blood, for example, you have type B
blood. Your blood sample will then be mixed with an anti-Rh serum. If your
blood cells clump together in response to the anti-Rh serum, it means that you
have Rh+ blood.
Your blood type can be determined
in a matter of minutes. Once you know your blood type, you can donate blood and
receive transfusions from donors in the compatible blood groups.