Modifying Risk of Aneuploidy with a Positive Cell-Free Fetal DNA Result

Clinical results after the implementation of cell‐free fetal DNA detection in maternal plasma

“…discovered the presence of cell‐free fetal DNA cell‐free fetal DNA (cffDNA) in maternal plasma in 1997, several methods have been developed to quantify and analyze it in order to use it as a noninvasive prenatal diagnosis test (NIPT). cffDNA originates in apoptotic trophoblastic cells being detectable since day 18 of gestational age (yet not enough to be analyzed until week 7–10) and disappears at the second day of post‐partum. The whole genome is represented in it in constant proportions.…”

“…The first one called shotgun MPS identifies sequences and maps informative sequences of every chromosome, therefore obtaining the relative quantity of each one. If a relative excess or deficit of any chromosome is found, it implies aneuploidy …”

“…These are amniocentesis (gold standard) and chorionic villus sampling (CVS). Even if these are relatively safe tests, there is a slight risk (0.22% in CVS and 0.13% in amniocentesis) of rupture of membranes, early delivery, chorioamnionitis, fetal loss and so on . As combined screening has a 5% false‐positive rate, it would be in these cases where replacing an IP for a noninvasive one in a contingent way could be appropriate.…”

“…However, these excellent results do not mean that it can be considered as a diagnostic test, due to the low prevalence of chromosomal disorders, predictive values are not as good, ranging from 37% to 98%. Therefore, it should be considered as a great screening strategy for high‐risk patients, in which aneuploidy prevalence is higher, and so would be predictive values . Any positive cffDNA result should be confirmed by IP …”

“…Therefore, it should be considered as a great screening strategy for high‐risk patients, in which aneuploidy prevalence is higher, and so would be predictive values . Any positive cffDNA result should be confirmed by IP …”