Cell-free DNA screening
for trisomy 13, 18 and 21

Healthcare Professional Space

Information for Healthcare Professionals

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A test on fetal DNA circulating in the maternal blood

Testing of the fetal DNA circulating in the maternal blood is used since many years in the follow-up of pregnancies, especially for fetal sex determination in the context of genetic diseases linked to chromosome X and for fetal Rhesus D determination in case of feto-maternal incompatibilities.

A prenatal test

The cell‐free DNA screening for trisomy 13,18 and 21 is a prenatal test performed on a simple blood sampling from the mother.

It enables, as early as the 10th week of gestation in pregnant women, to determine if the fetus carries a trisomy 21 or another aneuploidy of type 13 or 18.
Its sensitivity and specificity are greater than 99% for trisomies 13, 18 and 21.
When applied to the management of patients with increased risk of trisomy 21 without signs at ultrasound scan, it dramatically reduces (around 95%) the number of invasive procedures (amniocentesis or biopsy of chorionic villi) resulting into iatrogenic miscarriages in around 1% of cases.
In case of positive result of the Cell‐free DNA screening for trisomy 13,18 and 21, a fetal karyotype for confirmation will be performed.

Strategy for diagnosis of Down Syndrome

 Strategy diagnosis down syndrome EN

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