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Prenat Diagn. 2017 Dec;37(12):1238-1244. doi: 10.1002/pd.5174. Epub 2017 Nov 21.

Comparison of first-tier cell-free DNA screening for common aneuploidies with conventional publically funded screening.

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Dept. of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.
Dept. of Obstetrics & Gynecology, University of Calgary, Calgary, Alberta, Canada.
Dept. of Obstetrics and Gynecology, Université de Montréal, Montreal, Quebec, Canada.
Dept. of Medical Genetics and Pediatrics, Faculty of Medicine, Laval University, Québec City, Quebec, Canada.
Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec City, Quebec, Canada.
Human and Molecular Genetics Research Unit, Research Center, CHU de Québec, Quebec City, Quebec, Canada.
School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa, Ottawa, Ontario, Canada.



This study evaluates the impact of offering cell-free DNA (cfDNA) screening as a first-tier test for trisomies 21 and 18.


This is a prospective study of pregnant women undergoing conventional prenatal screening who were offered cfDNA screening in the first trimester with clinical outcomes obtained on all pregnancies.


A total of 1198 pregnant women were recruited. The detection rate of trisomy 21 with standard screening was 83% with a false positive rate (FPR) of 5.5% compared with 100% detection and 0% FPR for cfDNA screening. The FPR of cfDNA screening for trisomies 18 and 13 was 0.09% for each. Two percent of women underwent an invasive diagnostic procedure based on screening or ultrasound findings; without the cfDNA screening, it could have been as high as 6.8%. Amongst the 640 women with negative cfDNA results and a nuchal translucency (NT) ultrasound, only 3 had an NT greater or equal to 3.5 mm: one had a normal outcome and two lost their pregnancy before 20 weeks.


cfDNA screening has the potential to be a highly effective first-tier screening approach leading to a significant reduction of invasive diagnostic procedures. For women with a negative cfDNA screening result, NT measurement has limited clinical utility.

[Indexed for MEDLINE]

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