Abstract

RIVAS, Gabriela et al. Non-invasive fetal RHD genotyping in maternal plasma: Towards improved maternal and child care in Uruguay. Rev. Méd. Urug. [online]. 2026, vol.42, n.1, e207.  Epub Feb 12, 2026. ISSN 0303-3295.  https://doi.org/10.29193/rmu.42.1.13.

The Uruguayan regulation requires serological RhD determination for all maternal-neonatal dyads. Fetal RHD genotyping in maternal blood, performed with a nationally developed kit, allows for the identification of same-group maternal-fetal dyads, which could potentially prevent anti-D immunoglobulin prophylaxis.

This was a prospective, descriptive, single-cohort, multicenter study of 92 RhD-negative, non-alloimmunized pregnant women with a single-fetus pregnancy. A peripheral blood sample was collected between weeks 17 and 28 of gestation. An ATGen Laboratory kit was used via real-time multiplex PCR with TaqMan probes, allowing for simultaneous and differential amplification of three regions of the RHD gene (exons 5, 7 and 10). The results were compared with serological RhD determination in neonatal cord blood.

Out of 92 samples, 5 were discarded (2 from RhD-positive mothers and 3 with pre-analytical issues). Fifty-seven samples were positive for the three evaluated exons, with concordant Ct values and meeting the adequacy criteria defined in the insert (Cts≤37). For these 57 maternal samples, their neonate was positive via post-birth serological RhD antigen testing. The samples negative for the fetal RHD gene (n=30) were negative for the 3 exons of the kit, and it was confirmed that the RhD antigen in the cord blood was negative. The nationally produced molecular kit identified the three fetal exons in maternal plasma with 100% sensitivity and specificity, incorporating this new technology in Uruguay.

Keywords : Rhesus system (RHD); Anti-D immunoprophylaxis; Fetal genotype–maternal blood; RhD-negative pregnant women; Real-time PCR–RHD gene.

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