GP18\u2005Neonates born to rhesus positive women with perinatally-detected red cell antibodies: a case series

Abstract

Background Haemolytic Disease of the Fetus & Newborn (HDFN) results from maternal IgG red cell allo-antibodies crossing the placenta & binding to their corresponding antigen on red cells in the fetal circulation. Immune haemolysis can cause varying degrees of anaemia & unconjugated hyperbilirubinaemia in the fetus & neonate. At present, all women have bloods drawn for group & antibody screen at booking. For expectant mother who test RhD positive, repeat antibody screening is not carried out in the absence of antibodies at booking. We sought to determine if our unit was failing to identify neonates at risk of HDFN who were born to RhD positive mothers with negative antibody screening at booking who developed antibodies later during their pregnancy. Methods We carried out a retrospective chart review of babies born to women who booked with a negative antibody screen who subsequently produced a clinically significant antibody in that pregnancy, from 2011 to 2017 inclusive. The development of antibodies was detected incidentally via repeat maternal sampling or via repeat maternal testing following a positive Direct Coomb’s test on their baby. Results We identified 18 babies born to Rhesus D positive women who produced at least 1 of 8 clinically significant antibodies after their booking bloods were taken. 2 women tested positive for 2 antibodies. Any pregnancy where an immune Anti-D was produced was excluded. 2/3rd of the at-risk infant population were male and 1/3rd female. All tested DCT positive 14% of at-risk babies in the study group were diagnosed with jaundice; 2 due to Anti-E antibodies, 2 due to Anti-c antibodies & 1 each due to Anti-Jka, - Jka & -Jk3, Anti-Wra and Anti-Cw antibodies. 3 jaundiced neonates had no treatment. 4 needed phototherapy, of whom 2 also needed top-up red cell transfusion. 1 of these infants was later identified later as having Hereditary Spherocytosis accounting for his marked haemolysis and transfusion requirement. Discussion Based on the retrospective review of this small cohort of neonates in a single centre, a lack of routine repeat screening for their RhD positive mothers did not increase the risk of HDFN-associated morbidity nor mortality. We do not recommend routine repeat screening of Rhesus positive mothers for clinically-significant red cell allo-antibodies at 28–32 weeks in the absence of concern regarding haemolytic anaemia or jaundice in their babies. This would also confer a further 9,000 samples per year in our unit at a significant financial & workload cost with no evident gain for our neonatal population.