(Abstracted from Ultrasound Obstet Gynecol 2018;52:722–727)
Screening for chromosomal abnormalities based on cell-free fetal DNA (cfDNA) has been clinically available since 2011. While highly accurate for detection of trisomy 21, the accuracy of the test depends on the proportion of the total cfDNA that contains fetal genetic material (ie, the fetal fraction [FF]), with accuracy being higher when the FF is high and lower when the FF is low.
Perinatal Services, Monash Medical Centre (D.L.R.); Department of Obstetrics and Gynaecology, Monash University (D.L.R., F.D.S.C.); Monash Ultrasound for Women (F.D.S.C., T.J.L.), Clayton, Victoria, Australia; Roche Sequencing Solutions, San Jose, CA (M.S.); Discipline of Obstetrics, Gynaecology and Neonatology, University of Sydney (A.C.M.); and Sydney Ultrasound for Women (A.C.M.), Sydney, New South Wales, Australia