Read Blood Compatibility and Rh Protection
Compatibility depends on red-cell antigens meeting antibodies in the recipient’s plasma.
Blood Groups and Rh Prevention is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Predict ABO incompatibility
Group-A red cells carry A antigen. A group-B recipient has anti-A antibodies, so transfusion can cause agglutination.
Prevent Rh sensitisation
After an Rh-negative mother delivers an Rh-positive baby, anti-D immunoglobulin clears foetal red cells before the mother mounts a lasting immune response. This lowers risk in later Rh-positive pregnancies.
ABO and Rh incompatibility
Maternal anti-A or anti-B antibodies can clear fetal red cells carrying the corresponding ABO antigen before a strong anti-Rh response develops. Check the mother's antibodies against the baby's A/B antigens, separately from Rh status.
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- ✓Group B plasma contains anti-A.
- ✓Rh-negative mother + Rh-positive foetus → anti-D after delivery.
- ✓Prophylaxis protects future pregnancies.
Anti-D prophylaxis is given after exposure, not at conception.
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