Immunohematology and Blood Bank / Transfusion Medicine
Immunohematology and Blood Bank tests ABO/Rh typing, antibody detection, compatibility testing, component selection, and transfusion reaction investigation. Accuracy and clerical safety are central because errors can be fatal.
Core rules
- ABO forward grouping uses anti-A and anti-B reagents; reverse grouping uses A1 and B cells. Concordant results are required before reporting.
- RhD typing uses anti-D; weak D testing may be required by policy. Do not report RhD negative if weak D is unresolved.
- Antibody screen uses reagent red cells; positive screens require antibody identification and antigen-negative crossmatch selection.
- Immediate spin crossmatch detects ABO incompatibility; AHG crossmatch detects clinically significant IgG antibodies.
- DAT detects antibody or complement on patient red cells. A positive DAT after transfusion suggests immune hemolysis and requires investigation.
Worked example
Forward typing: anti-A 4+, anti-B 0, anti-D 4+. Reverse typing: A1 cells 0, B cells 4+. Interpretation: group A, RhD positive. Reasoning: forward detects A antigen; reverse detects anti-B in the patient’s serum. The results agree, so no discrepancy workup is needed. Crossmatch with A-positive or O-negative red cells according to policy.
Traps
Wrong blood in tube is a leading cause of ABO errors; recheck identity and repeat if discrepancy exists. Cold agglutinins and rouleaux can mimic reverse grouping problems. Underfilled EDTA tubes and hemolysis impair testing. In a transfusion reaction, stop the transfusion, check identity, and return the unit and tubing with samples per protocol.