Objective: The aim of this study was to examine the effectiveness of a combination of parameters at first-trimester screening for fetal aneuploidies, including ultrasound assessment of the nasal bone (NB), blood flow in the ductus venosus (DV) and flow across the tricuspid valve.
Methods: Screening for aneuploidy was carried out in 4172 singleton pregnancies between January 2006 and December 2010. Diagnostic accuracy of combined screening [inclusive of maternal age, fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein A] and of secondary ultrasound markers [NB, tricuspid regurgitation (TR) and Doppler studies of the DV] obtained at the same visit was assessed using the receiver operating characteristic (ROC) curve analysis.
Results: The individual areas under the ROC curves of NT, NB, DV or TR ranged between 0.7 and 0.8, representing acceptable discrimination. The area under the ROC curve of combined first-trimester screening was 0.87, whereas the addition of secondary ultrasound markers increased the area under the curve to 0.92, which represents excellent discrimination. At a risk cutoff of 1 : 275, the detection rate for aneuploidy increased from 87% to 92% (z statistic = 1.78, P = 0.076), and the false positive rate decreased from 5.3% to 4.8%.
Conclusion: The addition of secondary ultrasound markers (NB, DV and TR) to combined first-trimester screening showed a tendency toward improved accuracy of the screening.
© 2012 John Wiley & Sons, Ltd.