7. First- and Second-Trimester Screening for Fetal Aneuploidy and Neural Tube Defects

  1. John T. Queenan MD2,
  2. Catherine Y. Spong MD3 and
  3. Charles J. Lockwood MD4
  1. Julia Unterscheider MD and
  2. Fergal D. Malone MD

Published Online: 4 JAN 2012

DOI: 10.1002/9781119963783.ch7

Queenan's Management of High-Risk Pregnancy: An Evidence-Based Approach, Sixth Edition

Queenan's Management of High-Risk Pregnancy: An Evidence-Based Approach, Sixth Edition

How to Cite

Unterscheider, J. and Malone, F. D. (2012) First- and Second-Trimester Screening for Fetal Aneuploidy and Neural Tube Defects, in Queenan's Management of High-Risk Pregnancy: An Evidence-Based Approach, Sixth Edition (eds J. T. Queenan, C. Y. Spong and C. J. Lockwood), Wiley-Blackwell, Oxford, UK. doi: 10.1002/9781119963783.ch7

Editor Information

  1. 2

    Department of Obstetrics and Gynecology, Georgetown University School of Medicine, Washington, DC, USA

  2. 3

    Bethesda, MD, USA

  3. 4

    Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, New Haven, CT, USA

Author Information

  1. Department of Obstetrics and Gynaecology, Royal College of Surgeons in Ireland, Dublin, Ireland

Publication History

  1. Published Online: 4 JAN 2012
  2. Published Print: 24 FEB 2012

ISBN Information

Print ISBN: 9780470655764

Online ISBN: 9781119963783

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Keywords:

  • fetal aneuploidy, neural tube defects, first- and second-trimester;
  • prenatal screening for Down syndrome;
  • euploid fetuses, first-trimester sonographic;
  • ductus venosus examination, fetal blood vessel;
  • first-trimester serum and sonographic screening;
  • first-trimester cystic hygroma;
  • fetal anatomy, second-trimester sonographic;
  • stepwise sequential, and multiple different Down syndrome test;
  • screening in multiple gestations;
  • neural tube defect screening

Summary

Prenatal screening for Down syndrome and other aneuploidies, such as trisomies 13 and 18, has advanced significantly since its advent in the 1980s. Historically, women 35 years or older were offered prenatal genetic counseling and the option of a diagnostic test such as chorionic villus sampling or amniocentesis. With this screening approach, only 20% of the fetal Down syndrome population are detected antenatally. Sonographic and biochemical markers are now employed to screen for aneuploidies and neural tube defects in the first and second trimester. Maternal serum screening for Down syndrome in the second trimester started in the mid-1980s, with low levels of the analyte α-fetoprotein associated with an increased risk of fetal Down syndrome. Today, an increased nuchal translucency in the first trimester and/or a thickened nuchal fold in the second trimester are highly specific sonographic markers in trisomy 21 fetuses. Prenatal diagnosis should be made available, if requested, after appropriate counseling, including risks and benefits, to all pregnant women, regardless of maternal age.