Can AB Positive Patients Receive O Group Packed Red Blood Cells?
Yes, AB positive patients can safely receive O group packed red blood cells (PRBCs) as O is the universal donor for red blood cells, compatible with all ABO blood types including AB positive recipients.
ABO Compatibility for Red Blood Cell Transfusion
O group red blood cells are universally compatible because they lack both A and B antigens on the red cell surface, making them safe for transfusion to patients of any ABO blood type (A, B, AB, or O) 1.
AB positive patients are considered universal recipients for red blood cells in terms of ABO compatibility, meaning they can receive O, A, B, or AB red cells without risk of ABO-mediated hemolytic reactions 2.
The critical principle is that red blood cell compatibility depends on the antigens present on the donor red cells, not the antibodies in donor plasma (which are minimal in packed red cells) 3.
Emergency and Routine Transfusion Practice
O group PRBCs are routinely used for emergency transfusion in patients with unknown blood type, demonstrating the safety and universal compatibility of O red cells 4, 1.
A prospective study of 437 emergency patients receiving O RhD+ red blood cells showed this practice is safe, with the primary concern being Rh immunization in RhD-negative recipients (not relevant for AB positive patients), not ABO incompatibility 4.
Type O uncrossmatched blood has been used safely in trauma resuscitation for decades, with studies showing no transfusion reactions or blood incompatibility issues when transfusing O red cells to patients of other blood types 1.
Important Distinction: Red Cells vs. Plasma
This compatibility applies specifically to packed RED BLOOD CELLS, not plasma products 3.
For plasma transfusion, the compatibility rules are reversed: AB plasma is the universal donor (contains no anti-A or anti-B antibodies), while O plasma contains both anti-A and anti-B antibodies and should NOT be given to AB patients 3.
Fresh frozen plasma (FFP) should be the same group as the patient, and if blood group is unknown, group AB FFP is preferred 3.
Clinical Considerations
Crossmatching is still recommended when time permits to confirm compatibility and detect any irregular antibodies, even though ABO compatibility is assured 5.
One unit of PRBCs typically increases hemoglobin by approximately 1 g/dL in an average-sized adult who is not actively bleeding 5.
The decision to transfuse should be based on hemoglobin thresholds (typically 7-8 g/dL for stable patients) and clinical symptoms, not blood type compatibility concerns when using O red cells 3, 6, 5.
Common Pitfalls to Avoid
Do not confuse red cell compatibility with plasma compatibility—the rules are opposite for these two blood products 3, 2.
Do not withhold O red cells from AB patients based on misunderstanding of compatibility; this is a safe and appropriate transfusion 4, 1.
Do not assume that because AB patients are "universal recipients" they must receive AB blood—they can safely receive any ABO type of red cells, including O 2.