Fetal aneuploidy screening with cell-free DNA in late gestation

AbstractObjective: The aim of this study was to evaluate clinical use of NIPT at gestational ages of 23 weeks and above.Methods: A cohort of 5579 clinical patients with singleton gestations of 23 weeks or greater submitting a blood sample for NIPT in an 18-month period were selected for this study. Clinical outcomes were requested for samples with NIPT results indicating fetal aneuploidy and compared with NIPT findings to confirm concordance or discordance.Results: A review of clinical indications revealed that a significantly (p < 0.0001) larger proportion of late-gestation samples indicated abnormal ultrasound findings with or without other indications, 6.2% and 42.1%, compared with early-gestation samples, 1.8% and 6.0%, respectively. Of 5372 reported late-gestation samples, 151 (2.8%) were reported as aneuploidy detected or suspected. In late-gestation samples, the overall observed positive predictive value (PPV) for NIPT was 64.7%, with an observed PPV of 100% in the subset of cases with multiple cli...