title: Placental volume measured by three-dimensional ultrasound in the prediction of fetal alpha(0)-thalassemia: a preliminary report.
abstract: OBJECTIVE
  To evaluate the use of placental volume measured by three-dimensional (3D) ultrasound in predicting fetal homozygous alpha(0)-thalassemia (Hb-Bart's disease).
  
  
  METHODS
  From June 2002 to May 2004 singleton pregnancies at risk of alpha(0)-thalassemia and normal controls were studied prospectively at 9-12 weeks of gestation. Affected fetuses were suspected to have alpha(0)-thalassemia by two-dimensional (2D) ultrasound and confirmed by DNA analysis. Placental volume was measured on 3D ultrasound by a multiplanar technique. Intra- and interobserver agreement of measurements was assessed. The placental volume/crown-rump length quotient of the affected fetuses was compared with that of normal fetuses.
  
  
  RESULTS
  The final study group comprised 105 pregnancies; 43 were at risk of alpha(0)-thalassemia and 62 were normal controls. Eleven (10.5%) fetuses were affected by alpha(0)-thalassemia, all from the at-risk group, and the others were normal. Intra- and interobserver agreement of volume measurement by 3D ultrasound was relatively poor; this was reflected in the wide limits of agreement, which ranged from -10.82 to 40.86 mL. The mean +/- SD placental volume/crown-rump length quotient in affected pregnancies was larger than that in unaffected pregnancies (1.37 +/- 0.65 vs. 1.13 +/- 0.39), but this difference was not significant (P > 0.05).
  
  
  CONCLUSIONS
  Assessment of placental volume by 3D ultrasound does not seem to be superior to 2D ultrasound in the first-trimester prediction of alpha(0)-thalassemia.
authors.affiliation: Department of Obstetrics and Gynaecology, The University of Hong Kong, Queen Mary Hospital, Hong Kong.
authors.forename: M
authors.initials: M
authors.lastname: Chen
authors.forename: K Y
authors.initials: KY
authors.lastname: Leung
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: M H Y
authors.initials: MH
authors.lastname: Tang
authors.forename: P C
authors.initials: PC
authors.lastname: Ho
mesh_terms: D000328:Adult; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D005865:Gestational Age; D006720:Homozygote; D006801:Humans; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D009929:Organ Size; D010920:Placenta / Q000000981:diagnostic imaging* / Q000473:pathology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000592:standards; D017085:alpha-Thalassemia / Q000000981:diagnostic imaging* / Q000473:pathology