Component-specific reference
Select the component first. The same donor and recipient letters mean different things for red cells and plasma; platelets require a more nuanced laboratory decision.
Why the component matters
Red cells
Basic selection avoids donor red-cell A, B and RhD antigens that conflict with the recipient. The laboratory must type the blood, screen for clinically significant antibodies, confirm patient identity and crossmatch the actual unit.
Plasma
Plasma carries antibodies, so the basic ABO direction is different. This page does not treat the RhD sign as a simple plasma-selection rule.
Platelets
ABO-identical platelets are generally preferred, but antibodies, RhD, inventory and patient-specific requirements may alter selection. The laboratory decides.
Pregnancy RhD discussion reference
This view explains why a maternity team asks about RhD. It cannot determine the baby's blood group, antibody status, sensitisation or anti-D eligibility.
What actually determines care
- Antenatal ABO/RhD typing and antibody screening.
- Previous pregnancies, transfusions and known antibodies.
- Pregnancy events and tests assessed by the maternity team.
- Current local anti-D guidance, product availability and clinical eligibility.
Contact your maternity service promptly about bleeding, abdominal trauma or another concerning pregnancy event. This page cannot decide whether anti-D or another assessment is needed.
Basic red-cell donor reference
Recipient group is in the first column. These are ABO/RhD reference groups only, not permission to transfuse.
| Recipient | Basic red-cell donor groups listed |
|---|---|
| O− | O− |
| O+ | O−, O+ |
| A− | O−, A− |
| A+ | O−, O+, A−, A+ |
| B− | O−, B− |
| B+ | O−, O+, B−, B+ |
| AB− | O−, A−, B−, AB− |
| AB+ | O−, O+, A−, A+, B−, B+, AB−, AB+ |
Basic plasma donor reference
Plasma compatibility follows a different ABO direction because donor plasma may contain anti-A or anti-B. RhD is intentionally omitted from this simple table.
| Recipient ABO | Basic plasma donor ABO groups listed |
|---|---|
| O | O, A, B, AB |
| A | A, AB |
| B | B, AB |
| AB | AB |
Questions people ask
Does a green reference result mean transfusion is safe?
No. The result means only that the pairing appears in a basic ABO/RhD reference for the selected component. It does not evaluate the patient's identity, antibodies, history, the actual unit, or the clinical need for transfusion.
Why not call O-negative a universal donor?
O RhD-negative red cells are widely used when a patient's group is not yet known, but “universal donor” can hide component, antibody, stock and patient-specific constraints. Hospitals still follow emergency-release protocols and complete testing.
Can I use this page to find a donor?
No. Do not approach a person or request a particular unit based on this page. The treating hospital or licensed blood service manages donor collection, infectious-disease screening, component preparation and patient matching.
When should anti-D be given?
This page deliberately does not give a schedule. Eligibility and timing depend on tests, history, pregnancy events and current local guidance. Ask the maternity team responsible for the pregnancy.