Noninvasive Antenatal Diagnosis of Fetal RhD Status | Chapter 11 | Current Trends in Medicine and Medical Research Vol. 4
Introduction:
Fetal cell-free nucleic acids within the blood stream of a pregnant woman come
from fetal genetic material
which can be
acquired by simple
venipuncture that reduces
any risk to a
minimum. Fetal cell-free DNA can be detected in the mother's blood stream in the
5th gestation week at the earliest. That enables fetal genotyping at
the earliest possible stage of pregnancy which is best done in the 12th
gestation week.
Aim:
To determine fetal
RhD status at
RhD negative pregnant
women where the father is a
heterozygote, Dd.
Materials
and Methods: The research includes 1540 RhD
negative pregnant women, out of which at 30 of them the RhD fetal status had
been detected by a PCR technique from the mother’s plasma. The RhD fetal status
was confirmed after delivery by serologic analysis at 27 newborn babies. All
research patients were submitted to serologic immunohematology testing: blood
group typing of red blood cell
antigens, screening of
irregular anti-red blood
cell antibodies. Fetal RhD status
was determined by the plasma of RhD negative pregnant women using the real-time
PCR technology in the period from the 12th gestation week until the
31 gestation week. The biological fathers of all 30 fetuses were phenotyped as
heterozygote to the RhD antigen. The results showed that 30% of the fetuses are
RhD negative, and 70% are RhD positive.
Conclusion:
The noninvasive fetal RhD genotyping is not only one precious tool in the
management of RhD alloimmunised pregnancies,
but it also
allows antenatal anti-D
immunoglobulin prophylaxis exclusiveness
for only non-immunized RhD pregnant women carrying RhD positive fetus. Taking
into consideration that 30% of the RhD negative pregnant women that carry a RhD
negative fetus receive antenatal RhIG prophylaxis with no absolute need forit.
At RhD alloimmunised pregnant women the noninvasive genotyping of the fetal
blood group enables an easy and safe method in determination of a fetal risk
from a hemolytic disease, and at the same time evading a vast laboratory and
clinical monitoring of RhD antigen-negative fetal cases.
Author(s) Details
Dr. Emilija Velkova
Institute for Transfusion
Medicine of the Republic of Macedonia, Republic of Macedonia.
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