18, 91.0% (95% CI, for trisomy 13, 90.3% (95% CI, for monosomy X and 93.0% (95% CI, for sex chromosome aneuploidies other than monosomy X. For twin pregnancies, the DR for trisomy 21 was 93.7% (95% CI,

Objective: To review clinical validation or implementation studies of maternal blood cell-free (cf) DNA analysis in screening for aneuploidies and to explore the potential use of this method in clinical practice. Methods: Searches of PubMed and MEDLINE were performed to identify all peer-reviewed articles on cfDNA testing in screening for aneuploidies between 2011, when the first such study was published, and 20 December 2013. Results: Weighted pooled detection rates (DR) and false-positive rates (FPR) in singleton pregnancies were 99.0% (95% CI 98.2-99.6) and 0.08% (95% CI 0.03-0.14), respectively, for trisomy 21; 96.8% (95% CI 94.5-98.4) and 0.15% (95% CI 0.08-0.25) for trisomy 18; 92.1% (95% CI 85.9-96.7) and 0.20% (95% CI 0.04-0.46) for trisomy 13; 88.6% (95% CI 83.0-93.1) and 0.12% (95% CI 0.05-0.24) for monosomy X, and 93.8% (95% CI 85.9-98.7) and 0.12% (95% CI 0.02-0.28) for sex chromosome aneuploidies other than monosomy X. For twin pregnancies, the DR was 94.4% (95% 74.2-99.0) and the FPR was 0% (95% CI 0.00-1.84) for trisomy 21. Conclusion: An analysis of cfDNA in maternal blood provides effective screening for trisomies.

Objective To examine in a general population the performance of cell-free DNA (cfDNA) testing for trisomies 21, 18 and 13 at 10-11 weeks' gestation and compare