Gestational sac volume: comparison between SonoAVC and VOCAL measurements at 11 + 0 to 13 + 6 weeks of gestation.

Objectives: To assess the novel three-dimensional (3D) tool, Sonography-based Automated Volume Count (SonoAVC) in the calculation of gestational sac volume at 11 + 0 to 13 + 6 weeks of gestation, to correlate the measurements with those obtained using Virtual Organ Computed-aided AnaLysis (VOCAL) and to study the reproducibility of SonoAVC volume calculation of this irregularly shaped structure.

Methods: We acquired 3D volumes of the uterus in 65 pregnancies at 11 + 0 to 13 + 6 weeks of gestation. We performed volume calculation of the gestational sac, excluding the fetus and the placenta, using VOCAL with 15 degrees 12-step rotation. We then repeated the calculation with three different SonoAVC settings and compared both techniques. In 30 cases we assessed the reproducibility of the SonoAVC volume calculations.

Results: In 95% of cases it was possible to calculate the gestational sac volume with SonoAVC. This volume increased with advancing gestation and the volumes were expressed as delta values to compare the measurements made with VOCAL and the three different SonoAVC settings. There was no difference between delta values of gestational sac volume calculated using VOCAL and SonoAVC with high and medium growth settings. Reproducibility analysis showed good results.

Conclusion: Gestational sac volume calculation is feasible with SonoAVC in most cases and does not differ from that performed using VOCAL. High and medium growth SonoAVC settings seem to be more accurate for gestational sac volume calculation, although larger studies are required for standardization of the technique. The reproducibility analysis showed similar results to those previously published.