Determination of fetal RHD type in plasma of RhD negative pregnant women

Abstract

Alloimmunization against the RhD antigen is the most common cause of hemolytic disease of the fetus and newborn. Antenatal anti-D prophylaxis in addition to postnatal anti-D prophylaxis reduces the number of RhD-immunizations compared to only postnatal administration. Cell-free fetal DNA released from the apoptotic trophoblastic placental cells into the maternal circulation can be used to determine the fetal RHD type in a blood sample from an RhD negative mother. Based on this typing, antenatal anti-D prophylaxis can be recommended only to RhD negative women carrying an RhD positive fetus, since only these women are at risk of developing anti-D. The objective was to establish and validate a method for non-invasive fetal RHD typing. The fetal RHD genotype was studied in 373 samples from RhD negative pregnant women (median gestational week 24). DNA extracted from plasma was analyzed for the presence/absence of RHD exon 7 and 10 in a real-time PCR. The RHD genotype of the fetus was compared with the serological RhD type of the newborn. In 234 samples, the fetal RHD test was positive and in 127 samples negative. There was one false positive and no false negative results. In 12 samples, the fetal RHD type could not be determined, in all of them due to a maternal RHD gene. This method gives a reliable detection of fetal RHD positivity in plasma from RhD negative pregnant women. Antenatal anti-D prophylaxis based on the predicted fetal RhD type will avoid unnecessary treatment of pregnant women carrying an RhD negative fetus.

Cell free fetal DNA to triage antenatal rhesus immune globulin: Is it really cost‐effective in the United States?

“…5 National programs have now been implemented in Norway and Finland. 6,7 Implementation is currently being evaluated in England after the National Institute for Health and Care Excellence studied the issue for the National Health Service. 8 A national policy is being considered in Canada.…”

“…The Netherlands soon followed 18 months later with their national policy . National programs have now been implemented in Norway and Finland . Implementation is currently being evaluated in England after the National Institute for Health and Care Excellence studied the issue for the National Health Service .…”

En ung kvinne med transfusjonsutløst svangerskapskomplikasjon

“…Antistoffer mot blodtypeantigener i Kell-systemet kan, selv ved lave titere, forårsake alvorlig hemolytisk sykdom hos foster og nyfødt og til og med fosterdød. Kell-antigener uttrykkes også på forstadiene til erytrocytter, slik at disse destrueres etter antistoffbinding, erytropoesen hemmes og anemien blir langvarig (10) (11). Fremdeles vil det likevel vaere risiko for immunisering ved føtomaternell blødning før svangerskapsuke 28 og hos kvinner som kommer fra land uten optimal prenatal og postpartum-profylakseoppfølging.…”

Red blood cell alloimmunization in pregnancy: A 10-year single-center study

“…In the case of immunization, child's biological father is also being tested (ABO blood group, Rh phenotype, the presence of the specific antigen). Defining the RHD fetal genotype from fetal cells and cell-free fetal DNA (cffDNA) in maternal plasma has opened up opportunities for improved noninvasive prenatal testing and allowed invasive procedures, such as amniocentesis and chorionic villus sampling, to be abandoned [9]. Cordocentesis also can be done after week 18 of pregnancy, in order to perform the basic immunohaematological analysis and to detect and treat fetal anaemia in the pregnancies at risk (when pregnant women have clinically significant antibodies in a concentration above the critical titer).…”