Fetal genotyping with the use of cell-free DNA (cfDNA) technology can assist in screening for red blood cell (RBC) fetal antigens known to be associated with the development of hemolytic disease of the fetus and newborn (HDFN), including Rhesus D (RhD), according to a review published recently in the journal Current Opinion in Obstetrics and Gynecology.
The researchers evaluated the pathophysiology of HDFN, the mechanism via which the administration of RhD immune globulin (RhIg) prevents anti-RhD alloimmunization and the available information on the utilization of cfDNA screening to establish fetal RhD status.
Although RhIg is available for the preventive treatment of alloimmunization among RhD-negative women, anti-RhD alloimmunization continues to be a common cause of HDFN. Recently, shortages of RhIg supplies have resulted in the need for clinicians and professional societies to identify ways in which to guide the prioritization of RhIg administration.
Notably, new cfDNA tests that have the ability to predict fetal RBC antigen genotypes are being recommended as a potential option for triaging RhIg administration to RhD-negative pregnant women.
Read more about HDFN testing and diagnosis
Currently, a lack of guidance from US professional societies exists with respect to the routine utilization of cfDNA screening for fetal RhD status. This issue is exacerbated by the bundling of these tests with aneuploidy screening—in which fetal risk for chromosomal abnormalities is assessed—as well as inconsistent coverage by both the government and private insurers. All of these problems lead to widening the gap in health care disparities.
Results of a number of studies have shown that fetal RhD genotype tests have a high sensitivity and specificity for detecting fetal RhD status. Based on the currently reported shortage of RhIg, the American College of Obstetricians & Gynecologists (ACOG) suggests that the use of cfDNA tests for determining fetal RhD status is “a reasonable approach to prioritize RhIg administration when [the] supply is limited.”
It is quite likely that the usage of cfDNA screening for the status of fetal RhD and other RBC antigens will increase in routine clinical care.
The availability of real-world data to better comprehend the performance characteristics of cfDNA screening for fetal RhD status will help physicians manage RhD-negative patients in case there is a shortage of RhIg.
The authors concluded, “In anticipation of increased uptake of cfDNA screening for fetal [RhD] and other [RBC] antigen status, we recommend that laboratories decouple [RBC] antigen screening from aneuploidy screening and that government and commercial payers cover the costs of these tests, when indicated.”
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