OP09.27: Three‐dimensional measurement of gestational sac, and amniotic fluid volume in pregnancies affected by homozygous α‐thalassemia

Abstract

Objective: To evaluate the use of three-dimensional measurement of gestational sac and amniotic fluid volume in predicting homozygous α-thalassemia. We hypothesize that polyhydramnios, a sign of hydrops, is associated with affected pregnancies. Methods: Pregnancies at risk of homozygous α-thalassemia and normal controls were prospectively studied at 9–14 weeks of gestation using three-dimensional ultrasonography. Gestational sac and amniotic fluid volume were measured by multiplanar technique. Fetuses affected by homozygous α-thalassemia were predicted by two-dimensional ultrasonographic measurement of the fetal cardiothoracic ratio and placental thickness, and confirmed by an invasive test followed by DNA study. Results: From June 2002 to May 2004, 46 pregnancies at risk of homozygous α-thalassemia were prospectively studied. 11 of them were affected. The gestational sac volume and amniotic fluid volume increased with gestation and crown rump length. Mean (± SD) gestational sac volume /crown rump length quotient and mean (± SD) amniotic fluid volume /crown rump length quotient in affected pregnancies were larger than those in unaffected pregnancies (1.72 ± 0.55 vs 1.65 ± 0.49 and 1.55 ± 0.51 vs 1.40 ± 0.44, respectively). But the difference was not statistically significant (P > 0.05). Conclusions: It seems that three-dimensional gestational sac or amniotic fluid volumetry is not predictive of homozygous αthalassemia.