Improved first‐trimester Down syndrome screening performance by lowering the false‐positive rate: a prospective study of 9941 low‐risk women

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Abstract
Objective: To determine the performance of screening for Down syndrome (DS) and other major chromosomal abnormalities using nuchal translucency (NT), free β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) in a prospective study of a non‐selected population.Methods: Of 9941 women with an early ultrasound examination, NT was measured in 8622 singleton pregnancies with a gestational age between 10 + 3 and 13 + 6 weeks. β‐hCG and PAPP‐A were analyzed in 6441 cases. Detection rates (DR) and false‐positive rates (FPR) for the NT screening, the double test (β‐hCG and PAPP‐A) and the combined test (NT and the double test) were calculated using a 1 : 250 cut‐off.Results: NT could be measured in 97.5% of cases. The DR for DS with NT screening alone was 75% with a FPR of only 1.8%. The double test detected 73% and the combined test 91%, for FPRs of 8.8% and 2.1%, respectively. We detected 80% of fetuses with other major chromosomal abnormalities with a combination of NT screening and other ultrasound findings. Low β‐hCG and PAPP‐A values (below 0.4 MoM) were observed in 0.5% of the women including all cases of triploidy and trisomy 18 and 13.Conclusions: The performance of a screening strategy for DS using a combination of NT and the double test was superior to that using either NT or the double test alone due to a very low FPR and a higher DR. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Funding Information
  • The Danish Medical Research Council
  • Copenhagen University
  • The John and Birthe Meyer Foundation
  • The Ivan Nielsen Foundation
  • The Hede Nielsen Foundation
  • The Else and Mogens Wedell-Wedellsborg Foundation
  • The Dagmar Marshall Foundation
  • The Egmont foundation
  • The Fetal Medicine Foundation
  • The Augustinus Foundation
  • The Gangsted Foundation
  • The A. P. Møller Foundation
  • The Mads Clausens Foundation
  • Copenhagen Hospital Corporation

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