title: Study on the applicability of frontomaxillary facial angle in the first-trimester trisomy 21 fetuses in Chinese population.
abstract: OBJECTIVE
  To evaluate the measurement of frontomaxillary facial (FMF) angle at 11 weeks to 13 weeks, 6 days in a Chinese population and its applicability in the screening for fetal trisomy 21.
  
  
  METHODS
  In a retrospective study, the stored images for the measurement of fetal nuchal translucency (NT) thickness in a Chinese population from August 2003 to March 2007 were reviewed for the comparison of the FMF angle between 22 trisomy 21 fetuses (study group) with 220 randomly selected normal fetuses with satisfactory images (control group).
  
  
  RESULTS
  No association between FMF angle and NT, nasal bone length, or fetal heart rate was shown (P > 0.05). But the FMF angle was significantly greater in the trisomy 21 fetuses (89.7 vs 82.8, P < 0.001). The intraobserver and interobserver agreement were assessed in 9.5% (n = 21) normal cases. Mean (SD) differences of two observers were -0.83 (2.69) degrees (P > 0.05). For each observer, mean (SD) differences between the two paired measurements were -0.98 (3.11) degrees and 0.93 (1.80) degrees , respectively (P > 0.05).
  
  
  CONCLUSIONS
  Our results indicated that measurement of the FMF angle in the first trimester can be incorporated into the screening of trisomy 21 in the Chinese population, and its application is not affected by intraobserver and interobserver variability.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China. chenm@cuhk.edu.hk
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Tak Yeung
authors.initials: TY
authors.lastname: Leung
authors.forename: Daljit Singh
authors.initials: DS
authors.lastname: Sahota
authors.forename: Tak Yuen
authors.initials: TY
authors.lastname: Fung
authors.forename: Lin Wai
authors.initials: LW
authors.lastname: Chan
authors.forename: Terence Tzu-Hsi
authors.initials: TT
authors.lastname: Lao
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
mesh_terms: D000328:Adult; D044466:Asian People; D016022:Case-Control Studies; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005145:Face / Q000000981:diagnostic imaging* / Q000196:embryology; D005146:Facial Asymmetry / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D005260:Female; D005333:Fetus / Q000002:abnormalities / Q000033:anatomy & histology; D006801:Humans; D008437:Maxilla / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000196:embryology; D009295:Nasal Bone / Q000000981:diagnostic imaging / Q000196:embryology; D011153:Population; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055815:Young Adult