Andrew McLennan1,2, Ricardo Palma-Dias3,4, Fabricio da Silva Costa4,5, Simon Meagher5, Debbie L Nisbet3,6, Fergus Scott1,7. 1. Sydney Ultrasound for Women, Sydney, New South Wales, Australia. 2. Sydney University, Sydney, New South Wales, Australia. 3. Women's Ultrasound, Melbourne, Victoria, Australia. 4. University of Melbourne, Melbourne, Victoria, Australia. 5. Monash Ultrasound for Women, Melbourne, Victoria, Australia. 6. Royal Women's Hospital, Melbourne, Victoria, Australia. 7. University of New South Wales, Sydney, New South Wales, Australia.
Abstract
BACKGROUND: There 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. AIMS: To assess the implementation of NIPT into clinical practice utilising both first- and second-line screening models. MATERIALS AND METHODS: Three 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. RESULTS: NIPT 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). CONCLUSIONS: NIPT 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.
BACKGROUND: There 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. AIMS: To assess the implementation of NIPT into clinical practice utilising both first- and second-line screening models. MATERIALS AND METHODS: Three 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. RESULTS:NIPT 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). CONCLUSIONS:NIPT 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.
Authors: Dagmar Wertaschnigg; Maya Reddy; Ben W J Mol; Daniel L Rolnik; Fabricio da Silva Costa Journal: Aust N Z J Obstet Gynaecol Date: 2019-05-22 Impact factor: 2.100
Authors: Hilary Bowman-Smart; Julian Savulescu; Cara Mand; Christopher Gyngell; Mark D Pertile; Sharon Lewis; Martin B Delatycki Journal: Aust N Z J Obstet Gynaecol Date: 2019-02-06 Impact factor: 2.100