Fetal antigen testing appears to be the most effective way of assessing the risk of developing hemolytic disease in the fetus and newborn (HDFN), according to a recently published study in Transfusion Medicine Reviews.
These findings contradict the decade-long practice relying on paternal red blood cell (RBC) antigen testing.
HDFN is caused by alloimmunization, in which an immune response is directed towards a molecule (antigen) of another human. In HDFN, the response occurs against the Rh antigen present in the membrane of red blood cells in cases where the mother does not have an Rh antigen (Rh-negative) and the fetus does (Rh-positive).
For decades, testing for alloimmunization has consisted of testing the mother and father for Rh antigens; pregnancies in which the father is Rh-positive and the mother is Rh-negative are considered to be at risk for HDFN and require close monitoring.
Learn more about HDFN testing and diagnosis
However, paternal antigen testing has several limitations, such as misattributed paternity, the presence of genetic variants that can lead to false positive or false negative results, paternal unavailability and challenges in electronic medical records documentation.
“This lack of change in the obstetrical practice for predicting fetal RBC antigen status via paternal serologic testing likely stems from the historical inability to easily assess fetal RBC antigen status and an absence of other cost-effective testing methodologies,” the authors wrote.
The authors suggest that assessing the fetal RBC antigen status via direct analysis of fetal DNA could be a better alternative than paternal antigen testing, as it bypasses all of these risks.
Non-invasive fetal RBC antigen status techniques have been available for over two decades and are currently the standard of care in Europe.
“Ultimately, these less invasive tests can ensure accurate diagnosis without additional interventions requiring fetal monitoring, and perhaps more importantly, prevent misdiagnosis,” the authors said.
