What are the different blood types and their compatibility for transfusions?

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Blood Types and Transfusion Compatibility

The ABO blood group system consists of four main blood types (A, B, AB, and O) with type O being the universal donor that can be safely given to any recipient, while type AB is the universal recipient that can receive blood from any donor. 1

ABO Blood Group System

The ABO blood group system is one of the most important considerations in transfusion medicine and consists of:

  • Type A: Has A antigens on red blood cells and anti-B antibodies in plasma 1
  • Type B: Has B antigens on red blood cells and anti-A antibodies in plasma 1
  • Type AB: Has both A and B antigens on red blood cells but no anti-A or anti-B antibodies in plasma (universal recipient) 1
  • Type O: Has neither A nor B antigens on red blood cells but has both anti-A and anti-B antibodies in plasma (universal donor) 1

Rhesus (Rh) Blood Group System

In addition to the ABO system, the Rhesus (Rh) factor is another critical component:

  • Rh positive (Rh+): Has the Rh D antigen on red blood cells 2
  • Rh negative (Rh-): Lacks the Rh D antigen on red blood cells 2

Transfusion Compatibility Rules

ABO Compatibility

  • Type O can donate to all blood types (universal donor) 3
  • Type A can donate to types A and AB 1
  • Type B can donate to types B and AB 1
  • Type AB can only donate to type AB but can receive from all types (universal recipient) 1

Rh Compatibility

  • Rh+ can receive from both Rh+ and Rh- donors 2
  • Rh- should only receive Rh- blood to prevent sensitization 3
  • Rh- women of childbearing age who receive Rh+ blood or platelets can develop immune anti-D, which could affect future pregnancies 3

Emergency Transfusions

In emergency situations where time for blood typing is limited:

  • Group O Rh-negative is the blood group of choice for immediate transfusion 3
  • For male patients, O Rh-positive blood may be acceptable to conserve O Rh-negative supplies 3
  • Hospitals should try to obtain blood samples for grouping as soon as possible to allow transition to group-specific blood 3

Clinical Considerations

Massive Hemorrhage

In cases of massive hemorrhage requiring multiple units:

  • Type O RhD negative red cells should be used initially if the patient's blood group is unknown 3
  • Once the patient's blood group is determined, group-specific blood should be used 3
  • In emergency situations, blood can be issued following identification of blood group without waiting for antibody screen results 3

Platelet Transfusions

For platelet transfusions:

  • ABO-compatible products should be provided whenever possible 3
  • Incompatible plasma (e.g., O donor to A or B recipient) can put patients, particularly children, at risk of hemolysis 3
  • Plasma can be partially replaced with crystalloid platelet additive solution to reduce the amount of incompatible plasma 3

Special Situations

  • Alloimmunized patients with refractory thrombocytopenia may require HLA-matched platelets 3
  • For organ transplantation, donors and recipients should be matched as closely as possible for HLA-A, -B, and -DR antigens 3
  • Recent research has explored enzymatic conversion of A and B blood types to O to increase universal donor blood availability 4

Common Pitfalls and Caveats

  • Failure to properly identify the patient can lead to ABO-incompatible transfusions with potentially fatal consequences 3
  • Patients should have two identification bands in situ, and healthcare professionals must perform final administrative checks for every component given 3
  • Women who are RhD negative and of childbearing age who receive RhD positive blood require follow-up to prevent complications in future pregnancies 3
  • Overdependence on group O RhD negative red cells can adversely impact blood stock management 3
  • Transfusion-associated bacteremia should be suspected if patients experience severe febrile reactions during or shortly after platelet transfusions 3

By understanding blood type compatibility and following proper transfusion protocols, healthcare providers can ensure safe and effective blood component administration while minimizing the risk of adverse transfusion reactions.

References

1
Research

Biological and clinical aspects of ABO blood group system.

The journal of medical investigation : JMI, 2008

3
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Research

Toward universal donor blood: Enzymatic conversion of A and B to O type.

The Journal of biological chemistry, 2020

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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