Placental volume measured by three‐dimensional ultrasound in the prediction of fetal α0‐thalassemia: a preliminary report

Abstract

To evaluate the use of placental volume measured by three‐dimensional (3D) ultrasound in predicting fetal homozygous α⁰‐thalassemia (Hb‐Bart's disease). From June 2002 to May 2004 singleton pregnancies at risk of α⁰‐thalassemia and normal controls were studied prospectively at 9–12 weeks of gestation. Affected fetuses were suspected to have α⁰‐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. The final study group comprised 105 pregnancies; 43 were at risk of α⁰‐thalassemia and 62 were normal controls. Eleven (10.5%) fetuses were affected by α⁰‐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). Assessment of placental volume by 3D ultrasound does not seem to be superior to 2D ultrasound in the first‐trimester prediction of α⁰‐thalassemia. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.