Down's syndrome: First trimester approach

P. De Biasio, S. Ferrero, F. Prefumo, S. Canini, P. Marchini, I. Bruzzone, G. Ginocchio, P. L. Venturini

Research output: Contribution to journalArticlepeer-review


Objectives: The aim of our study was to evaluate the "combined test", a new first trimester screening test for Down's syndrome based on maternal age, ultrasound measurement of nuchal translucency thickness (NT), and maternal serum levels of pregnancy-associated plasma protein A (PAPP-A) and free β-hCG. Methods: The population attending our prenatal diagnosis unit was offered a first trimester scan. Nuchal translucency thickness measurements were performed by transabdominal ultrasound at 10-13 weeks of gestation. A blood sample was taken, and immunoradiometric assays for PAPP-A and free β-hCG performed. The risk of having an affected pregnancy was estimated from a multivariate Gaussian distribution, using a commercially available software. Results: A total of 1836 singleton pregnancies were enrolled. The gestational age, determined by ultrasound 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 16 cases of Down's syndrome pregnancies. With a risk cut-off of 1 in 350, 14 affected pregnancies were detected (detection rate 87%, 95% confidence interval: 62-98%) with a 3.3 percent false-positive rate. The odds of being affected given a positive result were 1 in 30. Conclusions: Our results confirmed the value of the combined test in first-trimester screening for Down's syndrome.

Original languageEnglish
Pages (from-to)22-26
Number of pages5
JournalItalian Journal of Gynaecology and Obstetrics
Issue number1
Publication statusPublished - 2001


  • Fetal nuchal translucency
  • Free β-hCG
  • Pregnancy-associated plasma protein A
  • Prenatal screening

ASJC Scopus subject areas

  • Obstetrics and Gynaecology


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