SMFM Guidance: Soft Markers on Ultrasound

SUMMARY:

Soft markers are ultrasound findings that do not represent a structural anomaly, may be a normal variant, but have been associated with increased risk for fetal aneuploidy. The soft markers are typically obtained at the time of the second trimester anatomy scan. SMFM has addressed the topic, with a focus on how to integrate these findings within current screening programs (NIPS and serum marker screening)

No Previous Aneuploidy Screening with Isolated Finding

  • Echogenic intracardiac focus | Echogenic bowel | Urinary tract dilation | Shortened humerus, femur (or both)
    • Screening option: NIPS or quad screening if NIPS not available or too expensive
  • Thickened nuchal fold | Absent or hypoplastic nasal bone
    • Counseling regarding risk for trisomy 21
    • Screening option: NIPS or quad screening if NIPS not available or too expensive or
    • Diagnostic option: Amniocentesis
  • Choroid Plexus Cysts
    • Counseling regarding risk for trisomy 18
    • Screening option: NIPS or quad screening if NIPS not available or too expensive

Negative Aneuploidy Screening Result with Isolated Finding

  • Echogenic intracardiac focus | Echogenic bowel | Urinary tract dilation | Shortened humerus, femur (or both)
    • No further aneuploidy evaluation
  • Thickened nuchal fold | Absent or hypoplastic nasal bone
    • No further aneuploidy evaluation
  • Choroid Plexus Cysts
    • No further aneuploidy evaluation
    • Counsel that the finding is a normal variant and not clinically relevant

KEY POINTS:

  • All pregnant women should be offered the option of diagnostic testing regardless of aneuploidy risk, consistent with their personal preferences
  • Diagnostic testing should not be offered based on isolated soft markers alone if there is a negative aneuploidy screening result (i.e., NIPS or serum marker screening)
  • Isolated single umbilical artery
    • No additional evaluation for aneuploidy (regardless if aneuploidy screening result is low risk or declined)
    • Recommended: Ultrasound in third trimester for growth
    • Consider: Weekly antenatal fetal surveillance beginning at 36w0d
  • Isolated urinary tract dilation
    • Recommended: Ultrasound ≥32 weeks to determine whether pediatric urology or nephrology follow-up is required
  • Isolated shortened humerus, femur, or both
    • Recommended: Ultrasound in the third trimester for growth
  • Isolated echogenic bowel
    • Recommended: Ultrasound in the third trimester for growth
    • Evaluate for cystic fibrosis and fetal cytomegalovirus infection

Learn More – Primary Sources:

Society for Maternal-Fetal Medicine Consult Series #57: Evaluation and management of isolated soft ultrasound markers for aneuploidy in the second trimester