Improved prenatal aneuploidy screening using the novel advanced first-trimester screening algorithm: a multicenter study of 10,017 pregnancies.

PURPOSE: : It has been postulated that the maternal age component should be completely excluded from first-trimester screening (FTS) for fetal aneuploidies. In this study, we tested a new algorithm known as advanced first-trimester screening (AFS), which disregards maternal age. METHOD: : In a multicenter study, FTS findings were retrieved from 10,017 pregnancies. FTS risk assessment was performed using the Nicolaides method, and the AFS score was calculated. The results of both methods were compared. RESULTS: : Within this population, 81 fetuses had an abnormal karyotype. The sensitivity of the 2 algorithms was 86.4%. When the AFS method was used, the positive predictive value rose from 9.6% (FTS) to 12.4% (AFS). Using AFS, the test positive rate could be decreased by 161 cases (-22.2%) (p < 0.0001), due to a reduction of false positive cases. As a result, the false positive rate of AFS was 24.5% lower than that of FTS, while the same number of aneuploidies was detected. CONCLUSION: : AFS can markedly reduce the rate of false positive test results. If these results are confirmed by larger multicenter studies, the new AFS will represent a great improvement in fetal aneuploidy screening. (c) 2008 Wiley Periodicals, Inc. J Clin Ultrasound, 2008.

Are nuchal translucency, pregnancy associated plasma protein-A or free-beta-human chorionic gonadotropin depending on maternal age? A multicenter study of 8,116 pregnancies.

INTRODUCTION: First-trimester screening according to Nicolaides uses maternal age to obtain a common background risk for trisomy 21. The likelihood ratios by nuchal translucency, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A are not with respect to maternal age. It was the aim of this study to investigate if likelihood ratios should better take care of it. MATERIALS: Pearson's correlation and different models of regression analysis had been performed on the results of 8,116 first-trimester screenings. The total number of pregnancies was subdivided into three subgroups of healthy fetuses (n = 8,038); fetuses with Down's syndrome (n = 46) and fetuses with other genetic abnormalities (n = 32). Statistical testing was applied to each of the three groups. RESULTS: Strong independence from maternal age could be found for each of the first-trimester screening measurement parameter, as well for healthy and as for affected fetuses. Neither Pearson's test nor nonlinear regression models could detect a correlation. Accordingly significance of Pearson's test is not given. DISCUSSION: First-trimester screening would not be improved by considering the maternal age in the calculation of the likelihood ratios. Therefore the currently used algorithm is adequate. According, to the results, it seems to be proper as well to disregard the maternal age in newer test strategies advanced first-trimester screening (AFS) at all.