Clinical Utility of Nuchal Translucency Measurement in First‐Trimester Ultrasound Screening in a Setting With First‐Tier NIPT for Aneuploidy Screening

Objective To investigate the additional clinical value of nuchal translucency (NT) measurement at the first‐trimester anomaly scan (FTAS) in a setting with first‐tier non‐invasive prenatal testing (NIPT). Method This nationwide prospective cohort study, part of the IMITAS study on FTAS implementation, included all pregnancies with increased NT (≥ 3.5 mm) at FTAS, subsequently referred for detailed diagnostic scans at eight Dutch tertiary centers (Nov 2021–Nov 2022). Women with abnormal dating scans, abnormal NIPT before FTAS, or high‐risk for fetal anomalies were not eligible for FTAS and received diagnostic ultrasound directly. The primary outcome was prenatal diagnosis of structural or genetic anomalies based on pre‐ and postnatal findings. Results FTAS was performed in 129,704 pregnancies, of which 230 (0.18%) had an increased NT. Anomalies were detected in 33.9% of these cases. Genetic anomalies included 76.8% aneuploidies, 14.3% SNVs, 8.9% CNVs; 39.3% beyond NIPT's detection scope. Trisomy 21/18 was diagnosed in 29.3% referred for increased NT without prior NIPT; 73.5% of these opted for termination. Anomaly prevalence increased with greater NT thickness. Conclusion NT measurement adds value in a national screening program including FTAS and NIPT. Prenatal counseling should address trisomies and other genetic abnormalities as a potential result of an abnormal FTAS, particularly when NIPT is declined.