Donor → Patient.Safe or Unsafe?
You get 30 seconds. Each card shows a donor's blood type and a patient's blood type. Tap Safe if the donor can give red cells to that patient. Tap Unsafe if they can't. Wrong taps cost points. Streaks pay bonus.
Learn ABO and Rh compatibility by playing
The Compatibility Challenge is a 30-second speed round: donor and patient pairs flash up and you decide whether the transfusion is safe or unsafe. It is built to drill the ABO and Rh compatibility grid into memory faster than reading a chart ever will.
Compatibility is not a trivia detail. Transfusing incompatible blood triggers a haemolytic reaction that can be fatal within minutes, which is why every hospital cross-matches before transfusion. Knowing the grid also makes you a better donor: O negative donors understand why they are called for trauma cases, and AB positive patients learn why they can receive from anyone.
The rules in short: type A carries A antigens, type B carries B, AB carries both, and O carries neither. Your plasma holds antibodies against the antigens you lack, so an A patient cannot receive B blood. Rhesus adds a second layer — Rh negative patients must not receive Rh positive blood, though Rh positive patients can take either.
Play a few rounds, then check your score against the leaderboard. When the pattern clicks, take the eligibility quiz and register as a donor.
Universal red cell donor
O negative red cells can go to any patient, which is why O negative supply is the first thing to run out in a mass-casualty event.
Universal recipient
AB positive patients can receive red cells from any group, but AB donors are the universal plasma donors.
Rhesus factor
Rh negative patients, especially women of childbearing age, must receive Rh negative blood to avoid sensitisation.
Why hospitals still cross-match
Beyond ABO and Rh there are minor antigen systems, so every unit is cross-matched against the patient before transfusion.
Frequently asked questions
- Is the game medically accurate?
- The pairs follow standard ABO and Rh red cell compatibility. It is an educational tool, not a clinical reference.
- Do I need an account to play?
- You can play immediately. An account lets your score appear on the leaderboard and keeps your streak.