(763) Implementation of a new rolling circle replication assay for universal non-invasive prenatal screening

To evaluate the uptake and performance of non-invasive prenatal aneuploidy screening (NIPS) using a new rolling circle replication assay.

Study Design: We conducted a prospective observational study of patients receiving prenatal care at a large county hospital. Patients with singleton pregnancies ≥ 10 weeks gestation were offered NIPS for trisomy 13, 18, and 21 using a non-sequencing based rolling circle replication assay (Vanadis system, PerkinElmer, Waltham, MA, USA) with analysis performed on-site. Individuals with abnormal screening results were offered diagnostic testing. We recorded results of invasive diagnostic testing and postnatal genetic testing if performed. Samples with diagnostic confirmation available were used to calculate predictive values.

Results: Among 14,127 patients who received prenatal care at our institution between August 2023 to July 2024, 11,631 (82.3%) elected NIPS. The mean BMI in this population was 29.5 ± 6.6 kg/m². There were 106 (0.9%) positive screening results, of which 46 had increased risk for trisomy 21, 32 for trisomy 18, and 28 for trisomy 13. There were 18 no-call results, with a no-call rate of 0.15%.  Of patients with diagnostic results available, abnormal screening results were confirmed in 16/19 (84.2%) patients who screened positive for T21, in 11/15 (73.3%) patients who screened positive for T18, and in 2/8 (25.0%) patients screened positive for T13. There were no false negative screens identified for any of these three aneuploidies.

Conclusion: Non-invasive prenatal screening using a rolling circle replication assay offers high sensitivity and specificity for aneuploidy screening with a low rate of no-call results. Positive predictive values for trisomy 21 and trisomy 18 far exceeded that for trisomy 13 screening.