Impact of Ultrasound Findings on the Positive Predictive Value of NIPT: A 24,263-Case Retrospective Study and a Stratified Prenatal Management Proposal
Year: 2026
Type: preprint
Study design: Observational Study
Abstract: Objective This study assessed how ultrasound findings affect NIPT positivity and PPV, aiming to optimize prenatal screening in pregnancies with ultrasound anomalies. Methods A retrospective study included 24,263 NIPT cases (3,258 abnormal, 21,005 normal ultrasound). Positivity rates, abnormal type distribution, and PPV were compared; all NIPT-positive cases had invasive confirmation. Subgroup analyses for isolated vs. multiple ultrasound anomalies were performed. Results NIPT positivity was significantly higher in the abnormal-ultrasound group (1.78% vs 1.16%, OR = 1.55, 95%CI 1.13–2.11, P = 0.006). Abnormal type distribution did not differ significantly (P = 0.058). PPV for Trisomy 21 (90.91% vs 87.88%, P = 1.000) and SCAs (41.67% vs 45.56%, P = 0.732) were similar. However, PPV for CNVs (microdeletions/microduplications) was markedly higher in the abnormal-ultrasound group (63.64% vs 8.70%, P < 0.001; absolute increase 54.94%). Subgroup: positivity was higher with multiple (1.32%) than isolated (0.73%) anomalies. CNVs predominated in isolated anomalies (60.0%), whereas Trisomy 21 predominated in multiple anomalies (71.4%). Conclusion Ultrasound anomalies increase NIPT positivity. CNVs dominate isolated anomalies; Trisomy 21 dominates multiple anomalies. An ultrasound-based stratified management is proposed: for multiple anomalies with positive NIPT, prioritize karyotyping; for isolated anomaly with positive NIPT, prioritize chromosomal microarray analysis; for normal ultrasound with positive NIPT, caution for false positives is warranted to guide counseling.
Source: Research Square
Institution: Jiangmen Central Hospital
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7161646948