SMFM Guidance – The Role of Prenatal Ultrasound and NIPT 

SUMMARY:

SMFM has released, as part of their Consult Series, a document on the role of prenatal ultrasound in the context of cfDNA screening.  The summary recommendations are as follows:

  • Negative cfDNA at 11-14 weeks: (evidence level 1B)
    • First trimester ultrasound only for NT measurement not recommended
  • Negative cfDNA and isolated ‘soft marker’: (evidence level 2B)
    • Diagnostic testing is not recommended solely for this indication
    • Describe ‘soft marker’ finding as ‘not clinically significant’ or ‘normal variant’
  • Negative 1st or 2nd trimester screen and isolated ‘soft marker’: (evidence level 2B)
    • Describe ‘soft marker’ finding as ‘not clinically significant’ or ‘normal variant’
  • Structural abnormality on ultrasound (evidence level 1A)
    • Offer diagnostic testing using microarray
  • Do not offer routine screening for microdeletions using cfDNA (evidence level 1B)

Key Points:

  • Examples of  ‘soft marker’ include echogenic intracardiac focus or choroid plexus cysts
  • ‘Isolated’ implies a single finding and the absence of any other pathology
  • If multiple ‘soft markers’ are identified
    • Refer for genetic counseling, consideration of diagnostic testing
    • prenatal risk assessment should be limited to expert centers and individuals

Levels of Evidence:

  • 1A: Strong recommendation; high-quality evidence
  • 1B: Strong recommendation; moderate-quality evidence
  • 2B: Weak recommendation; moderate-quality evidence

Learn More – Primary Sources:

SMFM Consult Series #42: The role of ultrasound in women who undergo cell-free DNA screening

ACOG Committee Opinion 682: Microarrays and Next-Generation Sequencing Technology: The Use of Advanced Genetic Diagnostic Tools in Obstetrics and Gynecology

ACOG Practice Bulletin 226: Screening for Fetal Chromosomal Abnormalities

ACOG Practice Bulletin 162: Prenatal Diagnostic Testing for Genetic Disorders

ACOG Practice Bulletin 175: Ultrasound in Pregnancy

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