An Rh-negative unsensitized multigravida at 32 weeks suffers an antepartum hemorrhage diagnosed clinically as abruptio placentae. Which investigation is used to quantify fetomaternal hemorrhage so that the appropriate dose of anti-D immunoglobulin can be calculated?

• A Indirect Coombs test on maternal serum
• B Direct Coombs test on cord blood
• C Liley curve analysis of amniotic fluid bilirubin
• D Kleihauer-Betke acid elution test on maternal blood ✓

Explanation

The Kleihauer-Betke test uses acid elution to identify fetal red cells containing hemoglobin F against adult cells in maternal blood, allowing estimation of the volume of fetomaternal bleed and calculation of extra anti-A beyond the standard prophylactic dose. Abruptio placentae is a recognized sensitizing event requiring assessment. The direct Coombs test confirms hemolysis in an already affected neonate, and the indirect Coombs screens for maternal antibodies rather than quantifying the bleed.

Reference: Williams Obstetrics, 25th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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