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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