There is wide variability in laboratory practices among institutions in the United States for monitoring the potential risk for hemolytic disease of the fetus and newborn (HDFN), according to findings from a survey recently published in the journal Transfusion.
HDFN is known to be triggered by maternal alloantibody-mediated destruction of fetal and neonatal red blood cells (RBCs). Although the pathophysiology of the disorder has been well described, the laboratory and clinical practices involved remain inconsistent throughout institutions in the U.S.
In the current analysis, the researchers surveyed a total of 103 U.S. institutions to assess laboratory testing and monitoring practices used for alloimmunized pregnant people with fetuses/newborns at risk of HDFN. They used Research Electronic Data Capture, which was hosted at Vanderbilt University Medical Center in Nashville, TN, to create the survey and manage the data.
The survey comprised questions regarding the following:
- Antibody testing methods in use
- Titration methodologies
- Utilization of critical titers
- Paternal and cell-free fetal DNA testing
- Reporting and documentation of fetal antigen results
The response rate to the survey was 44%, with 45 of the 103 institutions returning the survey. Overall, 64% of survey responses were from large hospitals that carried out more than 2000 deliveries yearly.
Read more about the testing and diagnosis of HDFN
Results of the study showed that maternal antibody titers were performed onsite at 93% of the institutions, as a send-out test at 2% of the centers, and are not carried out at all at 4% of the places surveyed. In all, 79% of the institutions that perform maternal antibody titers used conventional tube-based techniques only.
Additionally, 51% of the respondents rescreen all patients for antibodies in the third trimester. Overall, 60% of responding institutions reported that they conduct paternal RBC antigen testing.
Cell-free fetal DNA (cffDNA) testing for the prediction of fetal antigen status is used at 27% of the institutions surveyed. Of note, maternal antibody titers are performed even when the fetus is considered not to be at risk for HDFN, according to results of cffDNA or paternal antigen testing, at 23% (10 of 43) of the sites that evaluate titers.
This survey revealed that considerable differences exists among U.S. institutions with respect to testing, reporting, and monitoring practices among pregnant patients carrying fetuses at risk for HDFN. Lack of consistency of practice is further amplified by other factors in the U.S., the authors added, including a fragmented health care system in which patients’ blood bank/transfusion medicine (BBTM) records frequently are not shared among hospitals. Moreover, variability in BBTM testing methodologies across institutions exists as well.
“Standardization of laboratory testing protocols[,] and closer collaboration between the blood bank and transfusion medicine service and the obstetric/maternal-fetal medicine service[,] are needed,” the authors stated.
