Blood Group & Rh Typing Lab Test

Cross matching, ABO blood typing
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What is blood typing?

This is a test that is done to figure out the type of blood type in a person or which blood group they belong in. Not all people have the same blood group as there are many different types, of which some are more commonly found than others.

If your blood group matches another person's, then you are said to be "compatible" and could receive or give each other blood when required.

Why is blood typing done?

This procedure is usually done to know the type of blood group a person belongs to. Certain situations arise, such as:

  • When a person needs an organ transplant or blood transfusion, it is necessary that they know the blood group is compatible or not
  • When women are pregnant, it is important to know if the mother's blood and the child's are compatible
  • If you're donating blood, you need to know your type so doctors can give it safely

Newborn babies are also tested for certain diseases by having a blood typing test done on them.

Blood classification:

Blood is classified into different blood groups depending on the presence of certain substances. These can include antibodies which are a type of protein and antigens which are types of proteins and sugars and are found in plasma, which is the blood's liquid component.

Different cells have combinations of antigens on their surface and the immune system is aware of distinguishing these cells from foreign bodies such as toxins and bacteria.

The most common systems to classify blood are the ABO blood group in addition to the Rhesus (Rh) type.

The ABO group:

Two of the different antigens on the red blood cells' surface is known as antigen A and B. The ABO system is based on which type of antigen is present on the RBC.

The different types include:

• Blood Type A - The RBCs have only antigen A

• Blood Type B - The RBCs have only antigen B

• Blood type AB - The cells have both A and B antigens in them

• Blood Type O - Neither A or B antigen are present

In the plasma, there are antibodies against the antigens that aren't present in the RBCs.

• If one is in the A blood group, you'll have antibodies to the antigen B

• If one is in the B blood group, you'll have antibodies to the antigen a

• If one is in the AB blood group, you'll not have antibodies to the antigen B or A

• If one is in the O blood group, you'll have antibodies to the antigen B and A

The Rhesus system:

The other blood type is known as the Rhesus or the Rh system as it is named after the Rhesus monkey in which it was discovered for the first time. If the RhD antigen is on the surface of the red blood cells, then a person is said to be Rh+ and if it isn't, the person is Rh-

How is blood typing done?

The test to work out which part of the ABO blood group a person is in is known as the ABO blood typing which involves two steps such as:

1. Forward typing:

A blood sample is tested against 2 solutions in a laboratory - one with antibodies against the A antigen (Anti-A) and one that has an antibody against the B antigen (Anti-B)

The way blood reacts to antibodies is an indicator of which type of antigens are present in the blood. If you have the A antigen (you have the blood group A) when the anti-A antibodies are added, the blood cells will clump together in a process called agglutinating.

If it doesn't react for both, it must be the O-type.

Step 2 (Reverse typing)

In this step, the plasma (the fluidic part of the blood after the WBC and RBCs have been removed) and this is mixed with the type A blood first and then separately with type B to check the reaction.

Whether the agglutination takes place or not should be an indicator to confirm the forward typing results. Both types must agree on the same blood type.

Rhesus typing:

This is another type of test which can help determine the type of Rhesus blood type. In this test, a small sample of the RBC is mixed with a lab solution containing the antibodies to the RhD. If the blood reacts to the Rh test with agglutinating, it is called Rh positive and if it doesn't, it is Rh Negative.

Both the ABO and the RhD blood typing process are done all the blood collected from donors and for blood used for the transfusions in major hospitals. On occasion, testing is needed for the other red cell antigens, mostly in people who have rare disorders.

How can we help?

We will ensure that all the tests are done in a controlled environment with the best technicians. You will be able to find the results for the blood group ABO Rh test within a few days of undertaking the test.

Understanding results of Blood Group & Rh Typing

Reference RangeInterpretation
AA+/A-

‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

References

  1. https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=Rh_typing
  2. https://wa.kaiserpermanente.org/kbase/topic.jhtml?docId=hw3681
  3. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4732084/
  4. https://medlineplus.gov/ency/article/003345.htm
  5. http://www.mayoclinic.org/tests-procedures/rh-factor/about/pac-20394960
  6. https://labtestsonline.org.au/learning/test-index/blood-group
  7. https://labtestsonline.org/tests/blood-typing