Positive predictive value estimates for noninvasive prenatal testing from data of a prenatal diagnosis laboratory and literature review

Objective: Since 2011, noninvasive prenatal testing (NIPT) has undergone rapid expansion with both utilization and coverage. However, conclusive data regarding the clinical validity and utility of this testing tool, have lagged behind. Thus, there is a continued need to educate clinicians and patients about the current benefits and limitations to inform pre- and posttest counseling, pre/perinatal decision making, and medical risk assessment/management. Methods: : A retrospective study among women referred for invasive prenatal diagnosis to confirm positive NIPT results between January 2017 and December 2020. Prenatal diagnosis testing were taken including karyotype, chromosomal microarray analysis (CMA) or CNV-seq. Positive predictive values (PPV) were calculated. Results: : A total of 468 women were recruited. The PPVs for trisomy 21, 18, 13 were 86.1%, 57.8%, 25.0%, respectively. The PPV for RCAs and CNVs were 17.0%, 40.4% respectively. Detection of SCAs had PPV of 20% for monosomy X, 23.5% for 47,XXX, 68.8% for 47,XXY and 62.5% for 47,XYY. High-risk groups had a significant increase in the number of true positive cases compared to the low and moderate risk groups. Conclusion: T13, Monosomy X, RCA are associated with lower PPVs. Improvement of the cell-free fetal DNA screening technology and continued monitoring of its performance is important.