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ABO Blood CompatibilityNCLEX cheat sheet

ABO and Rh typing determines which blood a patient can safely receive, since transfusing incompatible blood triggers a deadly hemolytic reaction.

21 key facts 5 practice questions Reviewed Oct 2026
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Donor

  • O- = universal donor
  • AB+ = universal recipient

Rules

  • A gets A or O
  • B gets B or O
  • Rh- gives to + or -

Do

  • TWO RN verify at bedside
  • Y-tubing w/ NS only
  • Stay first 15 min, slow rate

Reaction

  • STOP transfusion immediately
  • Fever, chills, flank pain, ↓BP
  • Keep IV open w/ NS
Red flag to remember

Fever, chills, flank or back pain, dark urine, or hypotension during transfusion signal a hemolytic reaction; stop it at once.

Before you read

Test yourself first: 5 questions

Question 1 of 5

A nurse is preparing to administer a unit of packed red blood cells. Which safety action is essential before starting the transfusion?

What is abo blood compatibility?

Type O negative is the universal red cell donor, and type AB positive is the universal recipient. Correct patient and blood verification is one of the highest-priority safety checks in nursing.

Key points to remember

  • Type O negative red cells are the universal donor and are used in emergencies before typing.
  • Type AB positive is the universal recipient because the plasma has no A or B antibodies.
  • Rh-negative patients should receive Rh-negative blood to prevent sensitization.
  • Mismatched ABO blood causes an acute hemolytic transfusion reaction that can be fatal.
  • Two qualified staff must verify the patient and blood product identity at the bedside.
  • Blood is administered through a filtered set and only with normal saline.

Nursing priorities

  1. Verify patient identity, blood type, and unit number with a second nurse before starting.
  2. Stay with the patient and monitor vital signs closely during the first 15 minutes.
  3. Start the transfusion slowly and watch for early signs of a reaction.
  4. Stop the transfusion immediately at the first sign of a reaction and keep the IV open with saline.
  5. Use only normal saline with blood and never mix medications into the line.

Labs & values

Type and crossmatch required before transfusion
ABO groups: A, B, AB, O
Rh factor: positive or negative
O negative = universal RBC donor
AB positive = universal recipient

Patient teaching

  • Report any chills, itching, back pain, shortness of breath, or feeling unwell during a transfusion right away.
  • Understand the reason for transfusion and that staff will check vital signs frequently for safety.

Red flags: report now

  • Fever, chills, flank or back pain, dark urine, or hypotension during transfusion signal a hemolytic reaction; stop it at once.
  • Never hang blood that does not exactly match the verified patient and order.
  • Never infuse blood with any solution other than normal saline.

References

Clinical references for this topic

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