title: First-trimester screening for Down syndrome; the role of nasal bone assessment in the Korean population.
abstract: OBJECTIVE
  The aim of this study was to evaluate the role of nasal bone assessment in first-trimester screening for Down syndrome (DS) in the Korean population.
  
  
  METHODS
  From July 2004 to March 2006, we prospectively evaluated the fetal nasal bones at 11-14 weeks' gestation in the Korean population.
  
  
  RESULTS
  A successful evaluation was possible in 6490 of 6787 fetuses (95.6%). Absent, hypoechoic, and short nasal bones were seen in 4 (26.7%), 4 (26.7%), and 1 (6.7%) of 15 fetuses with DS, respectively, whereas in 5 (0.1%), 11 (0.2%), and 246 (3.8%) of 6456 normal fetuses. The incidence of absent and hypoechoic nasal bone showed significant differences between normal fetuses and fetuses with DS (P < 0.0005, both). Screening for DS using an absent or hypoechoic nasal bone resulted in a sensitivity of 53.3%, a specificity of 99.8%, a positive likelihood ratio of 215.2, and a negative likelihood ratio of 0.5.
  
  
  CONCLUSIONS
  Our study showed that nasal bone abnormality at 11-14 weeks of gestation had a high association with DS in the Korean population. This suggests that nasal bone assessment can be used to supplement the current first-trimester screening for DS in the Korean population.
authors.affiliation: Department of Radiology, Cheil General Hospital & Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea. moon@radiol.snu.ac.kr
authors.forename: Min Hoan
authors.initials: MH
authors.lastname: Moon
authors.forename: Jeong Yeon
authors.initials: JY
authors.lastname: Cho
authors.forename: Yu Mi
authors.initials: YM
authors.lastname: Lee
authors.forename: Sung Il
authors.initials: SI
authors.lastname: Jung
authors.forename: Jae Hyug
authors.initials: JH
authors.lastname: Yang
authors.forename: Moon Young
authors.initials: MY
authors.lastname: Kim
authors.forename: Hyun-Mee
authors.initials: HM
authors.lastname: Ryu
authors.forename: Jin Hoon
authors.initials: JH
authors.lastname: Chung
authors.forename: Seong Ho
authors.initials: SH
authors.lastname: Park
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007723:Korea; D009295:Nasal Bone / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal