Blood group immunology and pre-transfusion compatibility testing
Why ABO antibodies are IgM and dangerous while RhD, Kell and Kidd antibodies are IgG and acquired, what group and screen, DAT, IAT and the electronic crossmatch each detect, sample validity rules, RhD immunoglobulin dosing from a Kleihauer, and how daratumumab breaks the antibody screen.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Red cell antibodies come in two kinds. Naturally occurring IgM (anti-A, anti-B, and cold antibodies such as anti-M and anti-Lea) form without exposure. Immune IgG alloantibodies (anti-D, anti-K, anti-Jka, anti-Fya, anti-c, anti-E) form only after transfusion or pregnancy.
- IgM fixes complement well and causes intravascular haemolysis. Most IgG coats cells, which the spleen then removes: extravascular haemolysis.
- Pre-transfusion testing exists to find both: the ABO and RhD group (for the IgM) and the antibody screen (for the IgG).
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Sources
- Guidelines for transfusion and immunohaematology laboratory practice, 2nd edition (revised)AU/NZAustralian and New Zealand Society of Blood Transfusion, September 2026
- Guidelines for laboratory estimation of fetomaternal haemorrhage, 2nd editionAU/NZAustralian and New Zealand Society of Blood Transfusion, September 2021
- Guidance for RHD non-invasive prenatal testing for fetal RhD blood group prediction in pregnancy, 1st editionAU/NZAustralian and New Zealand Society of Blood Transfusion, November 2023
- Prophylactic use of Rh D immunoglobulin in pregnancy care: guideline summaryAU/NZNational Blood Authority and RANZCOG, 2021, summary updated 2024
- Haemolytic disease of the fetus and newborn (HDFN)AU/NZAustralian Red Cross Lifeblood, 2026
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy