Positive LR: ↑ risk of T21 compared with pretest risk due to presence of finding
Example: Absent nasal bone (NB) = 23x ↑ risk than a priori risk
Negative LR: ↓ risk of T21 compared with pretest risk secondary to absence of finding
Example: Normal NB = 50% less risk than a priori risk
Sonographic markers for aneuploidy are not anomalies
Most occur in normal fetuses
IMAGING
General Features
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Hu T et al: Prenatal chromosomal microarray analysis in 2466 fetuses with ultrasonographic soft markers: a prospective cohort study. Am J Obstet Gynecol. S0002-9378(20)31269-2, 2020
Wan JH et al: Use of noninvasive prenatal screening with cell-free DNA in late pregnancy with sonographic soft markers. Eur J Obstet Gynecol Reprod Biol. 252:431-3, 2020
Winter TC et al: How to integrate cell-free DNA screening with sonographic markers for aneuploidy: an update. AJR Am J Roentgenol. 210(4):906-12, 2018
Gil MM et al: Analysis of cell-free DNA in maternal blood in screening for aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 50(3):302-14, 2017
Wiechec M et al: How effective is first-trimester screening for trisomy 21 based on ultrasound only? Fetal Diagn Ther. 39(2):105-12, 2016
Abele H et al: First trimester ultrasound screening for Down syndrome based on maternal age, fetal nuchal translucency and different combinations of the additional markers nasal bone, tricuspid and ductus venosus flow. Prenat Diagn. 35(12):1182-6, 2015
Gil MM et al: Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 45(3):249-66, 2015
Vos FI et al: Nasal bone length, prenasal thickness, prenasal thickness-to-nasal bone length ratio and prefrontal space ratio in second- and third-trimester fetuses with Down syndrome. Ultrasound Obstet Gynecol. 45(2):211-6, 2015
Reddy UM et al: Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med. 33(5):745-57, 2014
Moreno-Cid M et al: Systematic review of the clinical prediction rules for the calculation of the risk of Down syndrome based on ultrasound findings in the second trimester of pregnancy. Prenat Diagn. 34(3):265-72, 2014
Agathokleous M et al: Meta-analysis of second-trimester markers for trisomy 21. Ultrasound Obstet Gynecol. 41(3):247-61, 2013
Related Anatomy
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References
Tables
Tables
KEY FACTS
Imaging
Top Differential Diagnoses
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Abbreviations
Trisomy 21 (T21)
Synonyms
Down syndrome
Definitions
Likelihood ratios (LR)
Positive LR: ↑ risk of T21 compared with pretest risk due to presence of finding
Example: Absent nasal bone (NB) = 23x ↑ risk than a priori risk
Negative LR: ↓ risk of T21 compared with pretest risk secondary to absence of finding
Example: Normal NB = 50% less risk than a priori risk
Sonographic markers for aneuploidy are not anomalies
Most occur in normal fetuses
IMAGING
General Features
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
Hu T et al: Prenatal chromosomal microarray analysis in 2466 fetuses with ultrasonographic soft markers: a prospective cohort study. Am J Obstet Gynecol. S0002-9378(20)31269-2, 2020
Wan JH et al: Use of noninvasive prenatal screening with cell-free DNA in late pregnancy with sonographic soft markers. Eur J Obstet Gynecol Reprod Biol. 252:431-3, 2020
Winter TC et al: How to integrate cell-free DNA screening with sonographic markers for aneuploidy: an update. AJR Am J Roentgenol. 210(4):906-12, 2018
Gil MM et al: Analysis of cell-free DNA in maternal blood in screening for aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 50(3):302-14, 2017
Wiechec M et al: How effective is first-trimester screening for trisomy 21 based on ultrasound only? Fetal Diagn Ther. 39(2):105-12, 2016
Abele H et al: First trimester ultrasound screening for Down syndrome based on maternal age, fetal nuchal translucency and different combinations of the additional markers nasal bone, tricuspid and ductus venosus flow. Prenat Diagn. 35(12):1182-6, 2015
Gil MM et al: Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis. Ultrasound Obstet Gynecol. 45(3):249-66, 2015
Vos FI et al: Nasal bone length, prenasal thickness, prenasal thickness-to-nasal bone length ratio and prefrontal space ratio in second- and third-trimester fetuses with Down syndrome. Ultrasound Obstet Gynecol. 45(2):211-6, 2015
Reddy UM et al: Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med. 33(5):745-57, 2014
Moreno-Cid M et al: Systematic review of the clinical prediction rules for the calculation of the risk of Down syndrome based on ultrasound findings in the second trimester of pregnancy. Prenat Diagn. 34(3):265-72, 2014
Agathokleous M et al: Meta-analysis of second-trimester markers for trisomy 21. Ultrasound Obstet Gynecol. 41(3):247-61, 2013
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