Estimation of Detection Rates of Aneuploidy in High-Risk Pregnancy Using an Approach Based on Nuchal Translucency and Non-Invasive Prenatal Testing: A Cohort Study.

OBJECTIVES The aim was to investigate aneuploidy detection using an approach based on nuchal translucency (NT) and non-invasive prenatal testing (NIPT). METHODS This was a cohort study including 5,306 high-risk pregnancies with NT measurements and chorionic villus samples (CVS) tested for full karyotype. RESULTS The fetal karyotype was normal in 4,172 (78.6%) cases and abnormal in 1,134 (21.4%), including 1,009 with a likely clinically significant adverse outcome. Universal CVS with full karyotyping would lead to the diagnosis of all clinically significant abnormalities. A policy of relying solely on NIPT would have led to the diagnosis of 88.9% of clinically significant abnormalities. A strategy whereby NIPT is the main method, with CVS reserved for cases with NT ≥3.0 mm, would require CVS in 21.7% of cases, identify 94.8% of significant abnormalities and avoid miscarriage in 41 pregnancies compared to CVS for all. CONCLUSIONS A policy of NIPT for increased-risk cases and CVS with full karyotype if the NT was ≥3.0 mm reduced the risk of miscarriage yet still identified 95% of clinically significant aneuploidy.