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The following is a summary of “Diagnostic Accuracy of Cell-Free DNA for the Determination of Fetal Red Blood Cell Antigen Genotype: A Systematic Review and Meta-Analysis,” published in the May 2025 issue of American Journal of Obstetrics & Gynecology by Mustafa et al. 

Researchers conducted a retrospective hematology study to specify the diagnostic accuracy of cfDNA in identifying fetal RBC antigen genotypes. 

They searched across 3 databases from 2000 to 2024. Cohort studies using cfDNA to detect fetal RBC antigens in pregnancies at risk of or with red cell alloimmunization were included, 2 reviewers independently screened studies and resolved disagreements through discussion. Reporting followed the Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and 2 authors independently extracted data and evaluated the risk of bias using the quality assessment of diagnostic accuracy studies (QUADAS-2) tool. Pooled sensitivity and specificity were estimated using a hierarchical summary receiver operating characteristic (HSROC) approach. Analyses were conducted overall and by laboratory methods, including polymerase chain reaction (PCR), next-generation sequencing (NGS), and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF). Subgroup analyses were conducted by antigen type: RhD, RhC, Rhc, RhE, Kell, and Duffy (Fy^a).  

The results showed that 84 studies with 77,187 antigen samples and neonatal genotype concordance were included. The PCR was used in 76 studies (75,692 samples), NGS in 5 (328 samples), and MALDI-TOF in 3 (1,167 samples). Across all techniques, cfDNA showed 99% sensitivity and specificity (95% CI 99-100) for fetal RBC antigen detection. Using PCR, pooled sensitivity and specificity were: RhD (74,786 samples) – 99% (95% CI 99-100) and 99% (95% CI 99-100); RhC (189) – 100% (95% CI 98-100) and 100% (95% CI 98-100); Rhc (232) – 99% (95% CI 96-100) and 100% (95% CI 94-100); RhE (276) – 100% (95% CI 97-100) and 100% (95% CI 99-100); Kell (209) – 99% (95% CI 96-100) and 100% (95% CI 98-100). With NGS, sensitivity and specificity were 100% across antigens: RhD (68) – (95% CI 96-100) and (95% CI 91-100); RhC (42) – (95% CI 92-100) and (95% CI 93-100); Rhc (52) – (95% CI 95-100) and (895% CI 83-100); RhE (88) – (95% CI 95-100) and (95% CI 97-100); Kell (108) – (95% CI 90-100) and (95% CI 98-100). The MALDI-TOF assessed RhD (1,167 samples) with 99% sensitivity and 98% specificity. Duffy (Fy^a) antigen was only assessed by NGS (19 samples) with 100% sensitivity and specificity.  

Investigators concluded that cfDNA accurately identified 6 fetal blood group antigens linked to red cell alloimmunization and offered earlier, less invasive detection than amniocentesis, supporting its integration into clinical practice to optimize care and reduce unnecessary interventions. 

Source: ajog.org/article/S0002-9378(25)00308-4/abstract