[Introduction of noninvasive prenatal testing for fetal trisomies: preliminary results and consequences on invasive...

Noninvasive prenatal testing (NIPT) has marked a revolution in aneuploidy screening because it allows a simple maternal blood test to detect trisomy 21, 18 and 13 in a foetus with a very high level of accuracy. After one year of NIPT utilisation with 683 samples, we analyzed retrospectively the performance of the test for 2014 : 3 positive samples (2 trisomies 21 and 1 trisomy 18) were correctly detected (100% sensitivity) and no foetal aneuploidy was missed for the pregnancies having already resulted in delivery by decembre 2014 (280 true negatif, 100% specificity). However, the additionnally available analysis of the sex chromosomes resulted in 2 erronous results: 1 uncorrect sex determination (1 male resulting in a female phenotype at birth) and 1 result suggesting a Turner syndrome was not confirmed by amniocentesis. The failure rate leading to a resampling was at 1.46% (10/683). The test used was the NIFTY of the BGI laboratory in Hong-Kong. By comparison to the year 2013, the utilisation of NIPT lead to a significant diminution of invasive samples performed by amniocentesis or choriocentesis 144 vs. 239 (- 63%). We confirmed that NIPT is a high-performance tool for the screening of the main foetal aneuploidies and report that during its first year of utilisation, 63% of invasive samples collected could be avoided. The test is expensive, not reimboursed by Luxembourg social security and therefore prohibitive for a number of women and their families.