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Trisomy 21
Roya Sohaey, MD
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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
                • Absent nasal bone = 23x ↑ risk than a priori risk
              • Negative LR: ↓ risk of T21 compared with pretest risk secondary to absence of finding
                • Normal nasal bone = 50% less risk than a priori risk
            • 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

                                1. 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
                                2. 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
                                3. 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
                                4. Wiechec M et al: How Effective Is First-Trimester Screening for Trisomy 21 Based on Ultrasound Only? Fetal Diagn Ther. ePub, 2015
                                5. 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
                                6. 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
                                7. Agathokleous M et al: Meta-analysis of second-trimester markers for trisomy 21. Ultrasound Obstet Gynecol. 41(3):247-61, 2013
                                8. Aagaard-Tillery KM et al: Role of second-trimester genetic sonography after Down syndrome screening. Obstet Gynecol. 114(6):1189-96, 2009
                                9. Odibo AO et al: Comparison of the efficiency of second-trimester nasal bone hypoplasia and increased nuchal fold in Down syndrome screening. Am J Obstet Gynecol. 199(3):281, 2008
                                10. Vergani P et al: Risk assessment for Down syndrome with genetic sonogram in women at risk. Prenat Diagn. 28(12):1144-8, 2008
                                11. Smith-Bindman R et al: Second trimester prenatal ultrasound for the detection of pregnancies at increased risk of Down syndrome. Prenat Diagn. 27(6):535-44, 2007
                                12. Tran SH et al: Ethnic variation in the prevalence of echogenic intracardiac foci and the association with Down syndrome. Ultrasound Obstet Gynecol. 26(2):158-61, 2005
                                13. Nicolaides KH: Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities. Am J Obstet Gynecol. 191(1):45-67, 2004
                                14. Souter VL et al: Correlation of second-trimester sonographic and biochemical markers. J Ultrasound Med. 23(4):505-11, 2004
                                15. Bromley B et al: The Genetic Sonogram Scoring Index. Semin Perinatol. 27(2):124-9, 2003
                                16. Graupe MH et al: Trisomy 21. Second-trimester ultrasound. Clin Perinatol. 28(2):303-19, 2001
                                17. Smith-Bindman R et al: Second-trimester ultrasound to detect fetuses with Down syndrome: a meta-analysis. JAMA. 285(8):1044-55, 2001
                                18. Winter TC et al: The "genetic sonogram": comparison of the index scoring system with the age-adjusted US risk assessment. Radiology. 215(3):775-82, 2000
                                19. Benacerraf BR et al: Sonographic scoring index for prenatal detection of chromosomal abnormalities. J Ultrasound Med. 11(9):449-58, 1992
                                Related Anatomy
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                                Related Differential Diagnoses
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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
                                              • Absent nasal bone = 23x ↑ risk than a priori risk
                                            • Negative LR: ↓ risk of T21 compared with pretest risk secondary to absence of finding
                                              • Normal nasal bone = 50% less risk than a priori risk
                                          • 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

                                                              1. 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
                                                              2. 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
                                                              3. 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
                                                              4. Wiechec M et al: How Effective Is First-Trimester Screening for Trisomy 21 Based on Ultrasound Only? Fetal Diagn Ther. ePub, 2015
                                                              5. 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
                                                              6. 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
                                                              7. Agathokleous M et al: Meta-analysis of second-trimester markers for trisomy 21. Ultrasound Obstet Gynecol. 41(3):247-61, 2013
                                                              8. Aagaard-Tillery KM et al: Role of second-trimester genetic sonography after Down syndrome screening. Obstet Gynecol. 114(6):1189-96, 2009
                                                              9. Odibo AO et al: Comparison of the efficiency of second-trimester nasal bone hypoplasia and increased nuchal fold in Down syndrome screening. Am J Obstet Gynecol. 199(3):281, 2008
                                                              10. Vergani P et al: Risk assessment for Down syndrome with genetic sonogram in women at risk. Prenat Diagn. 28(12):1144-8, 2008
                                                              11. Smith-Bindman R et al: Second trimester prenatal ultrasound for the detection of pregnancies at increased risk of Down syndrome. Prenat Diagn. 27(6):535-44, 2007
                                                              12. Tran SH et al: Ethnic variation in the prevalence of echogenic intracardiac foci and the association with Down syndrome. Ultrasound Obstet Gynecol. 26(2):158-61, 2005
                                                              13. Nicolaides KH: Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities. Am J Obstet Gynecol. 191(1):45-67, 2004
                                                              14. Souter VL et al: Correlation of second-trimester sonographic and biochemical markers. J Ultrasound Med. 23(4):505-11, 2004
                                                              15. Bromley B et al: The Genetic Sonogram Scoring Index. Semin Perinatol. 27(2):124-9, 2003
                                                              16. Graupe MH et al: Trisomy 21. Second-trimester ultrasound. Clin Perinatol. 28(2):303-19, 2001
                                                              17. Smith-Bindman R et al: Second-trimester ultrasound to detect fetuses with Down syndrome: a meta-analysis. JAMA. 285(8):1044-55, 2001
                                                              18. Winter TC et al: The "genetic sonogram": comparison of the index scoring system with the age-adjusted US risk assessment. Radiology. 215(3):775-82, 2000
                                                              19. Benacerraf BR et al: Sonographic scoring index for prenatal detection of chromosomal abnormalities. J Ultrasound Med. 11(9):449-58, 1992