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Prenatal aneuploidy screening

Part 1. Genetics

1.6. Genetic Medicine and Clinical Genetics

Basic Techniques and Approaches

  1. Katharine D. Wenstrom

Published Online: 15 APR 2005

DOI: 10.1002/047001153X.g106422

Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics

Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics

How to Cite

Wenstrom, K. D. 2005. Prenatal aneuploidy screening. Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics. 1:1.6:84.

Author Information

  1. University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA

Publication History

  1. Published Online: 15 APR 2005


Prenatal screening for birth defects gives the pregnant woman autonomy by providing her with information that she can use to decide either to continue the pregnancy or to terminate it. The most widely used prenatal screening tests are designed to detect fetal Down syndrome and trisomy 18. The basis of most of these screening protocols is the woman's age-related risk, which is modified by the results of a blood test and/or an ultrasound exam. Ultrasound can also be used to screen for major malformations and minor dysmorphisms that independently indicate increased aneuploidy risk. The woman is then counseled regarding the composite estimated risk of fetal aneuploidy determined by her screening tests, and offered a definitive diagnostic test. Currently, diagnostic testing can only be performed on fetal cells obtained by an invasive procedure such as amniocentesis or chorionic villous sampling, which each entail a finite risk of post-procedure pregnancy loss. Ultimately, the decision to undergo prenatal serum or ultrasound screening and then to undergo invasive testing must be made by the woman, on the basis of information provided during counseling and her own beliefs and values.


  • Down syndrome screening;
  • trisomy 18;
  • choroid plexus cysts