title: Three-dimensional ultrasound for nuchal translucency thickness measurements: comparison of transabdominal and transvaginal ultrasound.
abstract: OBJECTIVE
  We compared nuchal translucency (NT) thickness measurements using two-dimensional (2D) transabdominal, three-dimensional (3D) transabdominal, and 3D transvaginal ultrasound to determine levels of agreement.
  
  
  METHODS
  One hundred one pregnant women with a median gestational age of 12.6 weeks (range 11-14 weeks) were included in this study. First-trimester NT thickness measurements with 2D transabdominal ultrasound were performed on all women and were used as the gold standard. They also underwent 3D transabdominal and 3D transvaginal NT examinations. Both methods were compared with 2D transabdominal ultrasound measurements with respect to fetal nuchal translucency thickness, and levels of agreement were calculated by correlation coefficient.
  
  
  RESULTS
  There were no significantly different results between 2D transabdominal and 3D ultrasound. Furthermore, 3D transabdominal and 3D transvaginal measurements did not differ significantly. When 3-mm NT thickness was used as a cut-off level, however, there was a statistically significant overestimation of NT measurements by 3D transabdominal and 3D transvaginal ultrasound (median 1.4 mm versus 1.6 mm and 1.6 mm; P =.016 and P =.015 respectively) in the patient group with 2D transabdominal NT thickness less than 3 mm. In the patient group with 2D transabdominal NT thickness of 3 mm or more, there was a statistically significant underestimation of NT measurements by 3D transabdominal ultrasound (median 5.0 mm versus 4.6 mm; P =.002).
  
  
  CONCLUSIONS
  Two-dimensional transabdominal and 3D transabdominal and 3D transvaginal NT measurements differed minimally but significantly when compared with each other.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics and Gynecology, Vienna University Hospital, Vienna, Austria.
authors.forename: Christof
authors.initials: C
authors.lastname: Worda
authors.forename: Gerald
authors.initials: G
authors.lastname: Radner
authors.forename: Andreas
authors.initials: A
authors.lastname: Lee
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eppel
mesh_terms: D000005:Abdomen; D000293:Adolescent; D000328:Adult; D002869:Chromosome Aberrations; D005260:Female; D005313:Fetal Death; D005865:Gestational Age; D006801:Humans; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging* / Q000196:embryology*; D015588:Observer Variation; D011247:Pregnancy; D011256:Pregnancy Outcome; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014621:Vagina