Overview
Blood group discrepancies are forward and reverse ABO results (or related typing elements) that do not concord and therefore cannot support a released ABO interpretation until resolved or managed under written policy.
Classification
| Class | Serologic clue | Common associations |
|---|---|---|
| Missing reverse | Expected Ab weak/absent | Age, immune suppression, neonates |
| Extra reverse | Unexpected cell + | Anti-A1, cold Ab, rouleaux |
| Weak/missing forward | Expected Ag weak/absent | Subgroups, transfusion, suppression |
| Extra forward | Unexpected Ag reaction | Acquired B, technical/reagent issues |
Morphologic Features
Serologic pattern recognition, not cell morphology.
Laboratory Characteristics
- LIS discrepancy holds and analyzer flags
- Repeat/wash/incubate steps per SOP
- Possible A2 cells, O cells, or cold panel adjuncts
- Supervisory and medical-director escalation paths
Reference Intervals
No numeric cutoffs define discrepancy resolution universally. Enhancement times, accepted weak grades, and when to redraw are institutional, verify the current ABO discrepancy SOP.
Clinical and Laboratory Significance
Correct resolution prevents ABO-incompatible transfusion and clarifies whether emergency group O strategies are only interim measures.
Differential Considerations
Within each class, separate technical error, sample mix-up, subgroup/variant, cold antibody, disease-associated changes, and true alloanti-A1.
Comparison Tables
Resolution sequence (educational)
| Step | Purpose |
|---|---|
| Stop release | Prevent wrong ABO |
| Classify | Choose workup branch |
| Technical repeat | Catch method error |
| Category SOP tests | Resolve biologic cause |
| Document / escalate | Support care while pending |
Classification Frameworks
Not applicable.
Laboratory Notes
- Keep original and workup reactions on the record
- Historical type conflicts amplify urgency of identity checks
- Emergency RBCs do not close the discrepancy investigation
References
Authoritative textbooks, guidelines, and reviews supporting this reference entry. Verify reference intervals, critical limits, and reflex criteria against institutional protocols and current guideline editions.
Textbooks
- Cohn CS, Delaney M, Johnson ST, Katz LM, eds. Technical Manual. 21st ed. AABB; 2023.
- Harmening DM. Modern Blood Banking & Transfusion Practices. 7th ed. F.A. Davis; 2019.
- McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Elsevier; 2021.
CLSI and Professional Guidelines
- AABB. Standards for Blood Banks and Transfusion Services (verify current edition and institutional adoption).
- U.S. Food and Drug Administration. Code of Federal Regulations Title 21 . Blood and Blood Components (verify current institutional adoption).
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