Purpose: To access the yolk sac (YS) volume between 7 and 10 + 6 gestational weeks of pregnancy by threedimensional (3D) ultrasonography using extended imaging virtual organ computer-aided analysis (XI VOCAL) method. Methods: For this cross-sectional study, 64 pregnant patients between 7 and 10 + 6 gestational weeks were enrolled and normal pregnancies were included. The XI VOCAL 10 slices manual method was used for the YS volumetry by 3D ultrasonography. The statistical analysis first obtained the means, medians, standard deviation, and maximum and minimum volume values. The correlation of YS volume to the gestational age (GA) and the crown-rump length (CRL) was evaluated by models of polynomial regression, being adjusted by determination coefficient (R 2). Results: The mean YS estimated volume ranged from 0.06 ± 0.03 cm3 [0.02-0.11 cm3] to 0.16 ± 0.12 cm3 [0.01-0.38 cm3] and showed to be weakly correlated to the GA [YS volume = exp(0.261 x GA + 0.008); R2 = 0.14] and the CRL [YS volume = exp(0.033 x CRL + 0.035); R2 = 0.13]. Conclusions: The YS volume estimated by 3D ultrasonography using the method XI VOCAL correlated weakly with GA and CRL in normal singleton pregnancies between 7 and 10 + 6 gestational weeks.
- First trimester of pregnancy
- Three-dimensional ultrasonography
- Volume measurement
- Yolk sac