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Prenatal aneuploidy screening using cell free DNA

Cell free DNA (cfDNA) consists of small fragments of DNA that are present in the blood of pregnant women. Analysis of cfDNA can provide very accurate screening for trisomies 13, 18, and 21 and sex chromosomal abnormalities.The purpose of this document is to aid clinicians in counseling their patients regarding cell free DNA (cfDNA) screening, including the potential benefits and harms, a comparison to current screening tests, as well as the limitations and caveats.Cell free DNA for aneuploidy screening

Definition: Cell free DNA (cfDNA) consists of small fragments of DNA that are present in the blood of pregnant women. 

Clinical Use: Analysis of cfDNA can provide very accurate screening for trisomies 13, 18, and 21, and sex chromosomal abnormalities.

Summary

  • cfDNA has very high detection rates, and very low false positive rates, when used to test for Down syndrome and other common trisomies.
  • cfDNA does not detect all chromosomal abnormalities and women who desire comprehensive testing should be offered diagnostic testing.
  • cfDNA is a screening test and false positive results do occur. The chance that a positive result is a false positive is higher in low risk women. All positive results require counseling and the offer of confirmatory diagnostic testing before pregnancy termination is performed.
  • Failed cfDNA tests are associated with an increased risk of aneuploidy and diagnostic testing should be offered.


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