RESUMEN
As the classical first trimester Down syndrome screeningâ(FTS, combination test) has a false-negative rate of 20-25% and >â95% of the abnormal FTS results are false-positive, we evaluated the new Non-Invasive Prenatal Testâ(NIPT) in Belgium and the Netherlands. The study population consisted of 3000 consecutive pregnancies in Belgium and the Netherlands in which NIPT was performed using the Harmony test. In 57â(1.9%) of the 3000 pregnancies an abnormal NIPT result was found. This included 51 fetuses with trisomy 21, 4 fetuses with trisomy 18 and 2âfetuses with trisomy 13. In 47 of the 57 the NIPT result was confirmed by genetic testing of material obtained by amniocentesis or chorionic biopsy, and no false-positive results were recorded. The false-negative rate as determined on more than 2000 women that had delivered at the time of reporting was low, and so far only 2 false-negative results were reportedâ(one trisomy 18 and one trisomy 21). The failure rate where no NIPT result could be obtained after repeated sampling was 0.90%. In this large clinical series, NIPT using the Harmony test proves to be a very reliable prenatal test to detect fetal trisomies 21, 18 and 13 in maternal blood in Belgium and the Netherlands.