Blocked D in RhD hemolytic disease of fetus and newborn

Abstract

A 3-day-old term neonate was admitted to our hospital for the evaluation of neonatal jaundice. The neonate was born to an RhD-negative multiparous mother who had never received anti-D prophylaxis. The neonate's direct antiglobulin test was 4+. Blood group was B, and Rh D typing was negative using tube technique and positive (2+) using gel card. The mother had anti-D, and anti-D titers were 1:1024. After heat elution, RhD typing of the neonate was positive using tube (2+) and gel technique (4+). The eluate was shown to have anti-D. As the red cells of the neonate were saturated with maternal anti-D, commercial monoclonal anti-D could not bind to D antigen which resulted in false-negative D typing in the neonate. Such blocking phenomenon is rare. The discrepancy was identified while using two different techniques (tube and gel) which aided in early diagnosis and tailored an appropriate treatment. The neonate improved after the initiation of a combination of intravenous immunoglobulin and phototherapy.