Screening of RHD fetal genotype in RhD negative women

In the Czech Republic in all women within a first trimester screening a laboratory testing for RhD blood group from the peripheral blood should be performed. The aim of the screening is to diagnose RhD negative pregnant women, who may be at risk of developing RhD alloimmunization if the fetus is RhD positive. Currently, the prevention of RhD alloimmunization is carried out regardless of the knowledge of RHD fetal status. Already at the beginning of pregnancy it is possible to determine the RHD genotype of the fetus non-invasively due to cell free fetal DNA circulating in maternal peripheral blood detection. The issue of screening examination of fetal RHD genotype is solved worldwide. In some European countries, the examination is routinely established and thus contributes to the optimization of prenatal care for RhD negative pregnant women, immunoglobulin administration is targeted only in pregnancies with RhD positive fetus. The aim of our study is to evaluate clinical and laboratory effectiveness of fetal RHD genotype screening in RhD negative women by TaqMan Real-time PCR method. Designe: Prospective cohort study.

Obstetrics and Gynecology Clinic of the Faculty of Medicine University Palacky and the University Hospital Olomouc; Institute of Medical Genetics of the Faculty of Medicine UP and the University Hospital Olomouc; Transfusion Department of the University Hospital Olomouc; Institute of Biophysics of the Faculty of Medicine UP Olomouc.

In 2011-2015 at the University Hospital Olomouc 337 examinations of RHD fetal genotype were performed in pregnant women in first and second trimester and evaluated by TaqMan Real-time PCR, followed by verification of the newborn RHD genotype.

Methodology of fetal RHD genotype examination is accurate, reliable and useful in clinical practice. The sensitivity was 97.8%. The specificity was 98.7%. When assessing the effectiveness of the introduction of non- -invasive fetal RHD genotype screening in RhD negative women, it is necessary to assess the medical, organizational and economic aspects. More consistent prevention of RhD alloimmunization in the cases actually indicated may reduce the incidence of RhD alloimmunization.

From the medical point of view the RHD genotype determination in all RhD negative women at the beginning of pregnancy seems effective. It allows to diagnose about 40% of pregnancies with RhD negative fetuses that do not require administration of IgG anti-D. IgG anti-D should be administered only in indicated cases. Determination of fetal RHD genotype by using TaqMan Real-time PCR is useful in clinical practice.