Can a Person's Blood Group Change Over Time?
No, a person's inherent ABO and Rh blood group does not change under normal circumstances, as these antigens are genetically determined and remain stable throughout life. 1 However, there are exceptional clinical situations where apparent blood group changes can occur temporarily.
Normal Blood Group Stability
- ABO and Rh antigens are genetically encoded and expressed consistently from birth through adulthood in healthy individuals. 1
- Blood group antigens are integral components of the red blood cell membrane and are determined by inherited genes (ABO, H, and Secretor genes for ABO system; Rh genes for Rh system). 1
- These antigens are expressed not only on red blood cells but also on platelets, gastrointestinal epithelium, salivary glands, and respiratory system cells, making them fundamentally stable characteristics. 2
Exceptional Circumstances Where Blood Group May Appear to Change
Hematopoietic Stem Cell Transplantation
The only clinically significant scenario where blood group genuinely changes is after successful allogeneic hematopoietic stem cell transplantation (HSCT). 3
- In major ABO-incompatible transplants, the recipient's RBC blood type converts to the donor's blood type over an average of 56.6 days post-engraftment. 3
- In minor ABO-incompatible transplants, conversion occurs more rapidly at approximately 25.9 days. 3
- In bidirectional ABO-incompatible transplants, the conversion takes longest at approximately 67 days. 3
- The RBC chimeric ratio gradually shifts from recipient to donor type (1:9 ratio), ultimately achieving complete conversion to donor blood group. 3
Important caveat: Even after successful HSCT, the recipient's blood group substance (soluble antigens in body fluids) may help the original ABO blood type substance remain detectable, creating discrepancies between serological testing and actual RBC phenotype. 3
Transient Serological Discrepancies
- During the transition period post-HSCT, there can be contradictions between cell typing and serum typing due to residual recipient antibodies and emerging donor RBC antigens. 3
- Recipient anti-A or anti-B antibodies may persist after conditioning regimens but eventually disappear after full transformation. 3
- Some recipients may develop atypical antibody patterns during conversion (e.g., A recipients receiving O donor cells may produce anti-B instead of anti-A). 3
Clinical Implications for Blood Transfusion
- Accurate blood group typing is critical before transfusion, and serological testing remains the gold standard based on hemagglutination reactions. 4
- In post-HSCT patients, blood group testing becomes complex and requires careful interpretation of both cell typing and antibody screening. 3
- DNA-based testing can be used as a supplemental approach when serological methods cannot definitively determine blood groups, particularly in cases with recent transfusions or transplantation. 4, 5
Common Pitfalls to Avoid
- Do not assume blood group has changed based on a single discrepant test result—technical errors, recent transfusions, or sample handling issues can cause false results. 4
- In HSCT recipients, pre-transfusion testing must account for the transitional period where mixed-field reactions may occur due to coexisting recipient and donor RBCs. 3
- Blood group substance testing may show persistence of original blood type even after complete RBC conversion, which should not be misinterpreted as incomplete engraftment. 3