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Updated: Aug 9, 2026
FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Improved first-trimester Down syndrome screening performance by lowering the false-positive rate: a prospective study
K R Wøjdemann1, A C Shalmi, M Christiansen
1Copenhagen University Hospital, Department of Obstetrics and Gynaecology, Hvidovre Hospital, Copenhagen, Denmark. kwojde@dadlnet.dk
Objective:
To determine the performance of screening for Down syndrome (DS) and other major chromosomal abnormalities using nuchal translucency (NT), free beta-human chorionic gonadotropin (beta-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. beta-hCG and PAPP-A were analyzed in 6441 cases. Detection rates (DR) and false-positive rates (FPR) for the NT screening, the double test (beta-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 beta-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.
