Tests of haemolysis - direct antiglobulin test
What it detects
- *Detects IgG and/or complement (C3d) already bound in vivo to the patient's red cells*
- The test that separates immune from non-immune haemolysis - nothing else does
| Direct (DAT / direct Coombs) | Indirect (IAT) | |
|---|---|---|
| Sample | Patient's red CELLS | Patient's PLASMA |
| Detects | Antibody/complement already on the cells | Free antibody in the plasma |
| Uses | AIHA, HDFN, haemolytic transfusion reaction, drug-induced immune haemolysis | Antibody screen, crossmatch, antenatal screening |
- Method: wash the patient's red cells, add anti-human globulin (Coombs reagent) -> agglutination if antibody or complement is bound. Monospecific reagents (anti-IgG, anti-C3d) identify which
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