What it measures
The test finds your ABO blood group (A, B, AB or O) and whether your red cells carry the RhD antigen (RhD positive or RhD negative). It works by mixing red cells with antibodies and seeing which ones make them clump.
Why people test it
- Many people simply want to know their own blood group.
- Checked early in pregnancy, because RhD status affects antenatal care.
- Tested in hospital before surgery or a transfusion, alongside a screen for antibodies.
Typical range
There is no range and no normal or abnormal result. Labs report one of A, B, AB or O, followed by RhD positive or RhD negative.
Finger-prick or vein?
A finger-prick sample is usually enough. Home kits use a few drops of blood on a test card, and a vein sample is taken where the test is part of a wider panel.
Hospitals always test blood group themselves before a transfusion, so a home or private result is not used for that.