Clinically significant hemolytic disease of the newborn secondary to passive transfer of anti-D from maternal RhIG.

BACKGROUND

RhIG is used worldwide to reduce the incidence of alloimmunization to D during pregnancy. We report a case of clinically significant neonatal hemolysis mediated by maternally administered RhIG.

CASE REPORT

A 25-year-old, O-, primigravid mother with a negative antenatal antibody screen delivered a 6-lb 4-oz, blood group A, D+ baby girl at 36.5 weeks' gestation. Prenatal care included a dose of intramuscular RhIG at 28 weeks' gestation. At delivery, the newborn was markedly jaundiced with a total bilirubin of 6.3 mg/dL, which reached more than 20 mg/dL after 6 days. The newborn's lactate dehydrogenase (LDH) was 485 U/L (normal, <226 U/L) and further laboratory studies revealed reticulocytosis (17.2%; normal range, 0.36%-1.9%) and a hemoglobin (Hb) of 14.3 g/dL (normal for age range, 13.4-19.8 g/dL) that decreased to 11.5 g/dL (normal for age range, 13.5-22.6 g/dL) by Day-of-life 7. Although the maternal antibody screen was negative, the newborn's direct antiglobulin test (DAT) was positive for immunoglobulin (Ig)G, with an anti-D identified by elution studies. The possibility of hemolytic disease of the newborn (HDN) due to anti-A was considered, but ultimately ruled out by the absence of anti-A1 in the eluate. The newborn's hyperbilirubinemia was adequately managed with phototherapy. Analysis of the mother's plasma 10 days postpartum revealed an anti-D titer of 8. Two months after birth, the child's laboratory studies, DAT, antibody screen, and peripheral smear were unremarkable.

CONCLUSION

In the context of neonatal anemia, elevated LDH, and reticulocytosis, a positive IgG DAT with anti-D identified in the eluate suggests RhIG-mediated HDN. This appears to be a rarely reported event.