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Prenatal screening for chromosomal abnormalities

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The following summarized guidelines for the evaluation and management of prenatal screening for chromosomal abnormalities are prepared by our editorial team based on guidelines from the American College of Medical Genetics (ACMG 2022), the American College of Obstetricians and Gynecologists (ACOG/SMFM 2020), the Society of Obstetricians and Gynaecologists of Canada (SOGC 2020; 2017), and the National Society of Genetic Counselors (NSGC 2013).


1.Screening and diagnosis

Indications for screening, general principles, SMFM/ACOG: discuss and offer prenatal genetic screening (serum screening with or without nuchal translucency ultrasound or cell-free DNA screening) and diagnostic testing (chorionic villus sampling or amniocentesis) in all pregnant individuals regardless of maternal age or risk of chromosomal abnormality. Allow patients to pursue or decline prenatal genetic screening and diagnostic testing after review and discussion.
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  • Indications for screening (trisomies)

  • Indications for screening (deletions)

  • Indications for screening (sex chromosome aneuploidies)

  • Choice of screening test (general principles)

  • Choice of screening test (ultrasound)

  • Choice of screening test (maternal serum screening)

  • Choice of screening test (cell-free DNA)

  • Choice of screening test (amniocentesis, general population)

  • Choice of screening test (amniocentesis, at-risk population)

2.Diagnostic investigations

Further evaluation: provide genetic counseling and obtain a comprehensive ultrasound evaluation with an opportunity for diagnostic testing to confirm results in patients with a positive screening test result for fetal aneuploidy.
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3.Specific circumstances

Patients undergoing assisted reproductive technologies: as per ACOG 2020 guidelines, offer prenatal screening and prenatal diagnosis in all patients undergoing ART regardless of previous preimplantation genetic testing because preimplantation genetic testing is not uniformly accurate.

More topics in this section

  • Patients with twin pregnancies

  • Patients with multifetal gestation