Placental volume measured by three-dimensional ultrasound in the prediction of fetal α 0-thalassemia: A preliminary report

Abstract

Objective: To evaluate the use of placental volume measured by three-dimensional (3D) ultrasound in predicting fetal homozygous α 0-thalassemia (Hb-Bart's disease). Methods: From June 2002 to May 2004 singleton pregnancies at risk of α 0-thalassemia and normal controls were studied prospectively at 9-12 weeks of gestation. Affected fetuses were suspected to have α 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 α 0-thalassemia and 62 were normal controls. Eleven (10.5%) fetuses were affected by α 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 α 0-thalassemia. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.