External quality assessment of noninvasive fetal RHD genotyping

Frederik Banch Clausen, Åsa Hellberg

4 Citations (Scopus)


BACKGROUND AND OBJECTIVES: Fetal RHD genotyping of cell-free maternal plasma DNA from RhD negative pregnant women can be used to guide targeted antenatal and postnatal anti-D prophylaxis for the prevention of RhD immunization. To assure the quality of clinical testing, we conducted an external quality assessment workshop with the participation of 31 laboratories.

MATERIALS AND METHODS: Aliquots of pooled maternal plasma from gestational week 25 were sent to each laboratory. One sample was fetal RHD positive, and a second sample was fetal RHD negative. A reporting scheme was supplied for data collection, including questions regarding the methodological setup, results and clinical recommendations. The samples were tested blindly.

RESULTS: Different methodological approaches were used; 29 laboratories used qPCR and two laboratories used ddPCR, employing a total of eight different combinations of RHD exon targets. Fetal RHD genotyping was performed with no false-negative and no false-positive results. One inconclusive result was reported for the RHD positive sample. All clinical conclusions were satisfactory.

CONCLUSION: This external quality assessment workshop demonstrates that despite the different approaches taken to perform the clinical assays, fetal RHD genotyping is a reliable laboratory assay to guide targeted use of Rh prophylaxis in a clinical setting.

Original languageEnglish
JournalVox Sanguinis
Issue number5
Pages (from-to)466-471
Number of pages6
Publication statusPublished - Jul 2020


  • Exons
  • Female
  • Fetus/metabolism
  • Genotyping Techniques/standards
  • Humans
  • Plasma/chemistry
  • Pregnancy
  • Prenatal Diagnosis/standards
  • Real-Time Polymerase Chain Reaction
  • Rh-Hr Blood-Group System/blood
  • Rho(D) Immune Globulin
  • Rh prophylaxis
  • cell-free fetal DNA
  • fetal RHD genotyping
  • external quality assessment


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