In a proof-of principle study using this approach we were able to demonstrate detection of 6/7 (86%) of aneuploid fetuses with 0/165 (0%) false-positive results. Recently, the analysis of fetal cells from peripheral maternal blood has also been shown to be effective in helping to identify fetal aneuploidy. Īpplication of cf-DNA testing offers the opportunity to radically change prenatal screening but the introduction into actual clinical practice is challenging because of cost, differences in the scope of abnormalities detectable, and integration into existing testing. Starting from 2012 the identification of high-risk pregnant women was based on the result of contingent screening. According to this act, IPD is offered to all pregnant women ≥ 35years, or with positive serologic test, irrespective of maternal age. The Abruzzo Region, in central Italy, has regulated prenatal screening and diagnosis since 2001 with a regional law. National policies differ considerably with respect to the strategies implemented to achieve high detection rates but also to reduce IPD utilization. These new approaches have allowed high detection rates and reduced invasive testing (chorionic villus sampling (CVS) and amniocentesis) and, as a consequence, reduce costs and fetal losses. The purpose is to better select those pregnant women who would most benefit from invasive prenatal diagnosis (IPD). In recent years, many non-invasive prenatal testing approaches have been developed including measurement of maternal serum analytes, evaluation of specific ultrasound markers, and cell-free DNA (cf-DNA) analysis. We conclude that contingent screening using conventional Combined and second trimester screening tests is effective but can potentially be considerably enhanced through the addition of fetal cell analysis. For a sub-set of cases with positive contingent test results, FISH analysis of circulating fetal cells in maternal circulation identified 7 abnormal and 39 as normal cases with 100% specificity and 100% sensitivity. Additional chromosome abnormalities were also identified resulting in an OAPR for any chromosome abnormality of 1:6.6 (PPV 11.9%). For fetal Down syndrome, the overall detection rate was 96.8% for a false-positive rate of 2.8% resulting in an odds of being affected given a positive result (OAPR) of 1:11, equivalent to a positive predictive value (PPV) of 8.1%. From January 2014, analysis of fetal cells from peripheral maternal blood was also offered to women with positive screening results. The screening was based on first trimester cut-offs of ≥1:30 (IPD indicated), 1:31 to 1:899 (second trimester screening indicated) and ≤1:900 (no further action), and a second trimester cut-off of ≥1:250. From January 1 st 2013 to August 31 st 2016, 24408 pregnant women received the first trimester Combined test and contingently offered second trimester maternal serum screening to identify those women who would most benefit from invasive prenatal diagnosis (IPD).
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