Donation basics
Blood Group Compatibility Explained
Who can give to whom, and why it matters in emergencies.
The ABO and Rh rules
O− red cells can go to anyone (universal donor); AB+ patients can receive from anyone (universal recipient). Otherwise: a patient can receive from their own group, from O of compatible Rh, and A/B feed into AB.
The full donor table
A+ ← A+,A−,O+,O−; A− ← A−,O−; B+ ← B+,B−,O+,O−; B− ← B−,O−; AB+ ← all; AB− ← A−,B−,AB−,O−; O+ ← O+,O−; O− ← O− only.
Why platforms alert beyond the exact group
When HelpALife alerts donors for an A+ patient, O+ and O− donors are included — that's compatibility working for the patient, and it's why every group matters.
Frequently asked questions
Does plasma follow the same rules?
No — plasma compatibility is roughly reversed (AB is the universal plasma donor); hospitals handle this distinction.
Is Rh-negative rare in India?
Yes — only about 5% of Indians are Rh-negative, which is why O− and AB− donors are so valuable.