Kagan KO, et al. - A prospective randomized trial is conducted to compare the performance of first trimester combined screening (FTCS) with an approach that uses the combination of a detailed ultrasound examination and cfDNA analysis. This study has demonstrated that first-trimester screening for trisomy 21 that includes a detailed ultrasound examination and also NT measurement and is followed by cfDNA testing is related to an important reduction in the false positive rate compared to FTCS. This approach obviates the requirement for maternal serum free beta hCG and PAPP-A in screening for fetal aneuploidy.