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Cell free fetal dna test

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"noninvasive prenatal testing"

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ACOG cell-free DNA prenatal screening test FAQ limitations diagnostic testing

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https://www.acog.org/womens-health/faqs/prenatal-genetic-scr…

Cell-free fetal DNA (cfDNA) test, also called NIPT/NIPS, is a prenatal screening blood test.
  • What it measures: Small DNA fragments released mainly from the placenta into the pregnant person's blood. It does not directly sample fetal cells.
  • When: Usually from 10 weeks of pregnancy onward.
  • What it screens for: Most commonly:
    • Down syndrome, trisomy 21
    • Trisomy 18 (Edwards syndrome)
    • Trisomy 13 (Patau syndrome)
    • Some sex-chromosome differences, depending on the panel
  • Accuracy: It is the most accurate screening test for trisomies 21, 18, and 13, but it is not diagnostic. False-positive, false-negative, and "no-result" outcomes can occur. Tietz Textbook of Laboratory Medicine, p. 2758.
  • Does not reliably assess: All genetic diseases, birth defects, or neural-tube defects such as spina bifida. Ultrasound and the usual second-trimester screening remain important.
  • If high-risk/positive: Genetic counseling, a detailed ultrasound, and confirmation with CVS or amniocentesis should be offered before making decisions. ACOG guidance
  • If low-risk/negative: It greatly lowers the chance of the screened chromosome conditions but cannot completely exclude them.
  • If no-call/nonreportable: This can occur when the fetal fraction is low or for technical/biological reasons. It warrants discussion with the obstetric clinician because nonreportable results are associated with a higher chance of aneuploidy. ACOG guidance
ACOG states that cfDNA can be performed starting at 10 weeks and that a positive result should be confirmed with CVS or amniocentesis. ACOG patient information
Do you mean you want help understanding a specific cfDNA report? If so, share the result wording, gestational age, and whether it says low risk, high risk, or no-call, with personal details removed.
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