Cell-Free DNA Screening for Trisomy 21 in Twin Pregnancy: A Large Multicenter Cohort Study

Cell-free DNA (cfDNA) screening is an effective way to identify trisomy 21 in singleton pregnancies and has been shown to have both a high detection rate and a low false-positive rate. For twin pregnancies, however, there are challenges relating to fetal fraction and the ability to obtain and distinguish fetal DNA.