Blood Group Test
A blood test that finds your blood group (A, B, AB or O) and Rh type (positive or negative).
Quick Summary
Needed before blood transfusions, surgery and in pregnancy.
ABO group and Rh (D) type, and sometimes antibodies.
No preparation needed.
Overview
Blood groups must match for transfusions.
In pregnancy, an Rh-negative mother may need an injection (anti-D) to protect future babies.
What It Measures
ABO group
A, B, AB or O.
Rh type
Positive or negative.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Red Blood Cell Antibody Screen(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Blood groups(opens in a new tab) · NHS