Preferred Specimen(s) 3 ml Whole blood
Transport Container
- EDTA (lavender top tube),
- Red top tube
Transport Temperature Refrigerated, Stable 48 hrs
Reject Criteria Received frozen
Methodology Agglutination Method
Clinical Significance The indirect Coombs test is used in prenatal testing of pregnant women, and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient’s serum. In this case, serum is extracted from the blood, and the serum is incubated with RBCs of known antigenicity. If agglutination occurs, the indirect Coombs test is positive. A negative test in a woman who is pregnant means that she has not developed detectable antibodies against the fetus; e.g., no Rh sensitization.