LAUSR

Objectives: In most countries, non-invasive prenatal testing (NIPT) has been introduced commercially without any governmental guidance. In the Netherlands, prenatal screening for fetal anomaly is subject to a governmental license. NIPT has been implemented as part of the TRIDENT studies (Trial by Dutch laboratories for Evaluation of NIPT). TRIDENT-2 aims at offering NIPT to all pregnant women (∼174,000 women/year) within the national prenatal screening program. Since April 2017, women can choose NIPT as a contingent test after first-trimester combined testing (FCT), but may also choose NIPT as first-tier screening test. TheTRIDENT studies evaluate implementation and women's perspectives. Methods: All pregnant women in the Netherlands are offered prenatal screening and are counselled by certified counselors, generally midwives. A first-tier NIPT costs women € 175, comparable to the costs of FCT (∼€ 168). NIPT is performed by three Dutch university clinical genetic laboratories using an in-house validated test. Women can choose to have analysis of chromosomes 21, 18, and 13 without or with a report of incidental findings (findings other than trisomy 21, 13, 18) on the remaining autosomes, respectively, using the 'targeted' or 'whole genome' WISECONDOR pipeline. Sex chromosomes are not analyzed. Results: After 8 months of study, 48,234 tests have been performed (nationwide uptake of prenatal screening by NIPT as first-tier test was 40%), and 98.3% reports successfully issued. Failure rate was less than 2%. Mean turnaround time was 7 working days. 80% of women chose to have all autosomes analyzed. A total of 152 cases of T21 (0.3%), 32 cases of T18 (0.1%), 41 cases of T13 (0.1%), and 158 (0.3%) other chromosomal aberrations were found. First year results (and available follow-up) will be presented at the meeting. Conclusions: The Netherlands are the first country where NIPT is incorporated as a first-line test into a governmentally supported and health care funded prenatal aneuploidy screening program. The incorporation of the test in a university hospital laboratory and clinical service guarantees appropriate counselling and allows for proper follow-up. This 3-year study aims to provide all necessary information for a successful introduction of NIPT within the Dutch National prenatal screening program.