title: Association between first trimester absence of fetal nasal bone on ultrasound and Down syndrome.
abstract: OBJECTIVE
  To evaluate the association between absence of nasal bone on ultrasound and Down syndrome in fetuses at 11-14 weeks of pregnancy.
  
  
  METHODS
  One hundred and ninety-four consecutive fetuses from singleton pregnancies undergoing chorionic villi sampling (CVS) were evaluated by transabdominal ultrasound. A sagittal view of the fetal face was obtained and the absence or presence of nasal bone was recorded and correlated with the fetal karyotype.
  
  
  RESULTS
  A successful view of the fetal profile was possible in 183 of 194 (94%) fetuses. The nasal bone was absent in three of five fetuses with Down syndrome, and in one of 175 (0.6%) chromosomally normal fetuses.
  
  
  CONCLUSIONS
  Absence of nasal bone by first trimester ultrasound was significantly associated with Down syndrome. When a proper view of the fetal face was obtained, the nasal bone was visible in more than 99% of karyotypically normal fetuses.
authors.affiliation: Division of Obstetrics and Gynecology, Hospital Italiano de Buenos Aires, Argentine. lucas.otano@hosptialitaliano.org.ar
authors.forename: L
authors.initials: L
authors.lastname: Otaño
authors.forename: H
authors.initials: H
authors.lastname: Aiello
authors.forename: L
authors.initials: L
authors.lastname: Igarzábal
authors.forename: T
authors.initials: T
authors.lastname: Matayoshi
authors.forename: E C
authors.initials: EC
authors.lastname: Gadow
mesh_terms: D000328:Adult; D000782:Aneuploidy; D015415:Biomarkers; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007621:Karyotyping; D008423:Maternal Age; D009295:Nasal Bone / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000196:embryology*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D016216:Ultrasonography, Prenatal
chemical_list: D015415:Biomarkers