Effectiveness of placental volume measured by virtual organ computer-aided analysis in prediction of fetal hemoglobin Bart's disease in late first trimester

Abstract

Objective: To evaluate the effectiveness of placental volume measured by virtual organ computer-aided analysis (VOCAL) at 12 to 14 weeks of gestation in predicting fetal hemoglobin (Hb) Bart's disease among pregnancies at risk.

Methods: This study involves 3-dimensional ultrasound (3D-US) volume datasets derived from pregnancies at risk of fetal Hb Bart's disease at 12 to 14 weeks of pregnancy. VOCAL technique was used to measure and calculate placental volume by the authors, who did not know the fetal diagnosis. Placental thickness was also measured. The diagnostic values of placental volume and placental thickness in prediction of fetal Hb Bart's disease were calculated.

Results: Sixty-five volume datasets, including 22 datasets of the affected fetuses and 43 unaffected fetuses, were included. The mean placental volume (±SD) of the affected cases was significantly higher than that of the unaffected ones, 85.35 ± 20.84 cm³ vs 52.24 ± 19.01 cm³ (Student's t test, P < .001). In predicting Hb Bart's disease, placental volume and placental thickness had sensitivities of 77.3% and 72.7% respectively as well as specificities of 88.37% and 76.7% respectively.

Conclusion: Of fetuses at risk of Hb Bart's disease, 3D-US VOCAL placental volume may be useful in early detection of affected fetuses. Its effectiveness is superior to that of conventional placental thickness measurement.

Keywords: hemoglobin Bart's disease; homozygous alpha-thalassemia-1 disease; placental thickness; placental volume; virtual organ computer-aided analysis (VOCAL).