• Andrew McLennan, Ricardo Palma-Dias, da Silva Costa Fabricio F University of Melbourne, Melbourne, Victoria, Australia. Monash Ultrasound for, Simon Meagher, Debbie L Nisbet, and Fergus Scott.
• Sydney Ultrasound for Women, Sydney, New South Wales, Australia.
• Aust N Z J Obstet Gynaecol. 2016 Feb 1; 56 (1): 22-8.

BackgroundThere are limited data regarding noninvasive prenatal testing (NIPT) in low-risk populations, and the ideal aneuploidy screening model for a pregnant population has yet to be established.AimsTo assess the implementation of NIPT into clinical practice utilising both first- and second-line screening models.Materials And MethodsThree private practices specialising in obstetric ultrasound and prenatal diagnosis in Australia offered NIPT as a first-line test, ideally followed by combined first-trimester screening (cFTS), or as a second-line test following cFTS, particularly in those with a calculated risk between 1:50 and 1:1000.ResultsNIPT screening was performed in 5267 women and as a first-line screening method in 3359 (63.8%). Trisomies 21 and 13 detection was 100% and 88% for trisomy 18. Of cases with known karyotypes, the positive predictive value (PPV) of the test was highest for trisomy 21 (97.7%) and lowest for monosomy X (25%). Ultrasound detection of fetal structural abnormality resulted in the detection of five additional chromosome abnormalities, two of which had high-risk cFTS results. For all chromosomal abnormalities, NIPT alone detected 93.4%, a contingent model detected 81.8% (P = 0.097), and cFTS alone detected 65.9% (P < 0.005).ConclusionsNIPT achieved 100% T21 detection and had a higher DR of all aneuploidy when used as a first-line test. Given the false-positive rate for all aneuploidies, NIPT is an advanced screening test, rather than a diagnostic test. The benefit of additional cFTS was the detection of fetal structural abnormalities and some unusual chromosomal abnormalities.© 2016 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

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