A 3-day-old term neonate presents with jaundice. Total serum bilirubin is 18 mg/dL, direct bilirubin 0.3 mg/dL. The neonate's blood group is A positive and the mother's is O positive. DAT (Coombs) is weakly positive. The most specific test to confirm ABO hemolytic disease of the newborn in this setting is:
- A Peripheral smear for spherocytes
- B Elution test from baby's red cells ✓
- C Maternal indirect Coombs test
- D G6PD assay on neonate's blood
Correct answer: B. Elution test from baby's red cells
Explanation
The elution test demonstrates anti-A or anti-B antibodies that are bound to the neonate's red cells by eluting them and reacting the eluate against A or B red cells — this is the most specific confirmatory test for ABO HDN. A weakly positive DAT alone is insufficient because DAT can be weakly positive in normal neonates born to O-group mothers. Spherocytes on peripheral smear support hemolysis but are non-specific. Maternal indirect Coombs tests for free antibody in maternal serum. G6PD assay is relevant if enzyme-deficiency jaundice is suspected.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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