In a prospective, multicenter blinded study at 35 international centers, the Noninvasive Examination of Trisomy (NEXT) study evaluated the performance of cell-free DNA screening for fetal trisomy compared to standard first trimester screening with nuchal translucency and serum analytes in a routine prenatal population. Among the 15,841 women who had standard screening and cell-free DNA analysis with neonatal outcome data, there were 68 chromosomal abnormalities (1 in 236). Of these, 38 were Trisomy 21 (1 in 417). Cell-free DNA analysis had a higher area under the curve (AUC) for trisomy 21, compared to standard screening (0.999 vs. 0.958, p = 0.001). Cell-free DNA analysis also had greater sensitivity, specificity, and positive predictive value compared to standard screening for trisomy 21, 18, and 13. While cell-free DNA analysis cannot detect all chromosome abnormalities, it performed better than standard screening for detection of trisomies 21, 18, and 13 in a routine population including low- and high-risk women.
The importance of ultrasound preceding cell‐free
DNA
screening for fetal chromosomal abnormalities