https://www.karger.com/Services/SiteLicensesNicolaides, KyprosSyngelaki, ArgyroGil, MarPoon, LeonaWright, David2025-06-142025-06-142013-10-261015-38371421-996410.1159/00035606610.1097/01.ogx.0000455020.22084.3ehttps://ror.circle-u.eu/handle/123456789/404244<jats:p>&lt;b&gt;&lt;i&gt;Objective:&lt;/i&gt;&lt;/b&gt; To examine potential performance of screening for trisomies by cell-free (cf) DNA testing in maternal blood contingent on results of first-line testing by combinations of fetal translucency thickness (NT), fetal heart rate (FHR), ductus venosus pulsatility index (DV PIV), and serum-free β-human chorionic gonadotropin (β-hCG), pregnancy-associated plasma protein-A (PAPP-A), placental growth factor (PLGF) and α-fetoprotein (AFP). &lt;b&gt;&lt;i&gt;Methods:&lt;/i&gt;&lt;/b&gt; Performance was estimated for firstly, screening by cfDNA in all pregnancies and secondly, cfDNA testing contingent on results of first-line testing by combinations of ultrasound and biochemical markers. &lt;b&gt;&lt;i&gt;Results:&lt;/i&gt;&lt;/b&gt; In first-line screening by cfDNA testing, the detection rate for trisomy 21 and trisomies 18 or 13 would be 99 and 96%, respectively, after invasive testing in 1% of the population. In contingent screening, a detection rate of 98% for trisomy 21 and 96% for trisomy 18 or 13, at an invasive testing rate of 0.7%, can be achieved by carrying out cfDNA testing in about 35, 20 and 11% of cases identified by first-line screening with the combined test alone (age, NT, FHR, β-hCG, PAPP-A), the combined test plus PLGF and AFP and the combined test plus PLGF, AFP and DV PIV, respectively. &lt;b&gt;&lt;i&gt;Conclusions:&lt;/i&gt;&lt;/b&gt; Effective first-trimester screening for trisomies can be achieved by contingent screening incorporating biomarkers and cfDNA testing.</jats:p>CLOSEDCell-Free SystemChromosomes, Human, Pair 13Trisomy 13 Syndrome610Chromosome DisordersTrisomyDNAPregnancy Trimester, FirstPregnancy616HumansFemaleDown SyndromeChromosomes, Human, Pair 18BiomarkersMaternal Serum Screening TestsTrisomy 18 Syndromepublication03 medical and health sciences0302 clinical medicine3. Good healthdoi_dedup___24192489