First-trimester screening for Down syndrome using nuchal translucency measurement with free β-hCG and PAPP-A between 10 and 13 weeks of pregnancy—the combined test

✍ Scribed by P. De Biasio; M. Siccardi; G. Volpe; L. Famularo; F. Santi; S. Canini

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 153 KB
• Volume: 19
• Category: Article
• ISSN: 0197-3851
• DOI: 10.1002/(sici)1097-0223(199904)19:4<360::aid-pd556>3.0.co;2-u

✦ Synopsis

In a population of 1467 women attending the 'G. Gaslini' Institute for antenatal care, we evaluated first-trimester risk screening for Down syndrome using the 'combined test' based on ultrasound measurement of nuchal translucency (NT), maternal serum pregnancy-associated plasma protein A (PAPP-A) and free -hCG, and maternal age. No clinical action was taken on these results.

The gestational age, determined by scan measurement of crown-rump length, ranged from 10 weeks to 13 weeks 6 days. The median maternal age was 31 years 8 months. There were 13 Down syndrome pregnancies. The risk of having an affected pregnancy was estimated from a multivariate Gaussian distribution, using commercially available software.

With a risk cut-off of 1 in 350, 11 affected pregnancies were detected (detection rate 85 per cent, 95 per cent confidence interval: 56-100 per cent) with a 3.3 per cent false-positive rate. The odds of being affected given a positive result were 1 in 30. Further data are needed to determine, with greater statistical reliability, the relative performance of the combined test with current second-trimester screening.