Unusual Rhesus Antibodies as a Cause for Fetal Isoimmunisation

Abstract

Hemolytic disease of the newborn due to Rh isoimmunisation in a Rhesus D (Rh-D) negative mother with an Rh-D positive fetus is a well recognised entity. Although antibody to Rh-D antigen (anti-D antibody) was once the major cause of hemolytic disease of the fetus and newborn (HDFN), widespread adoption of antenatal and postnatal prophylactic anti-D immunoglobulin administration has resulted in a marked decrease in the prevalence of allo-immunisation due to the Rh-D antigen during pregnancy. However, at the same time, the maternal allo-immunisation to other red cell Rhesus antigens became more evident as a cause for HDFN, since no prophylactic immunoglobulins are available to prevent the formation of these antibodies. The authors report a case of a pregnant woman with AB negative blood group and positive indirect Coombs test (ICT) with rising middle cerebral artery peak systolic velocity (MCA-PSV) on follow up visits. Fetus required intrauterine transfusion. Fetal cord blood sampling revealed the fetus to be B negative and the direct Coombs test (DCT) was positive. On further testing, maternal serum was found to be positive for anti-D, anti-C and anti-G antibodies. Postnatally, the baby required double volume exchange transfusion. The authors highlight the importance of irregular antibody screening for women with obstetric history suggestive of HDNF. This could help in diagnosis and successful treatment of the affected fetus.