A blood test known as a monocyte monolayer assay (MMA) appears to accurately predict the severity of hemolytic disease of the fetus and newborn (HDFN) and should be implemented in routine clinical practice, according to the authors of a recently published study in SSRN.
HDFN is caused by maternal antibodies transmitted to the fetus through the placenta. These antibodies bind to proteins such as the Rh antigen in the membrane of fetal blood cells, serving as markers that indicate to immune cells called monocytes that the red blood cell in question must be ingested and destroyed.
Currently, prenatal HDFN screening mostly consists of the detection of these antibodies in blood samples. However, recent studies suggest that antibody detection alone can not accurately predict whether HDFN will occur or how severe it will be.
Read more about HDFN testing and diagnosis
MMA is a blood test based not on detecting disease-causing antibodies but on quantifying how monocytes respond to these antibodies. An MMA assesses whether the presence of maternal antibodies will lead to HDFN and how severe it will be.
The authors aimed to evaluate the efficacy and accuracy of MMA for predicting HDFN occurrence and its severity with a study that included 15 pregnant women with positive Rh antibodies who were tested with both an antibody detection test and an MMA.
Results showed that the MMA predicted the HDFN occurrence accurately in 13 of the 15 cases. MMA also correctly predicted the severity of the disease in 80% of the cases, showing a superior performance compared to the antibody detection test.
The authors recommend MMA to be performed in the third trimester of pregnancy, as samples taken during the first and second trimesters could provide false negative results.
“Although the MMA test is time-consuming, it is convenient for laboratory operation and can efficiently predict the severity of neonatal hemolytic disease. Therefore, we recommend that this test is routinely used in clinical practice.” the authors wrote.
