Reference ranges of fetal adrenal gland and fetal zone volumes between 24 and 37 + 6 weeks of gestation by three-dimensional ultrasound

Abstract

Objective: To establish reference ranges of the fetal adrenal gland (AG) and fetal zone (FZ) volumes using three-dimensional ultrasound (3DUS).

Methods: We performed a prospective cross-sectional study with 204 normal singleton pregnancies between 24 and 37 + 6 weeks of gestation. The fetal AG and FZ volumes were obtained using the virtual organ computer-aided analysis method with a 30° rotation. To establish reference ranges as the function of gestational age (GA), quantile regression was performed with the adjusted coefficient of determination (R²). Intra- and inter-observer repeatability was performed using the intraclass correlation coefficient (ICC).

Results: The mean results of fetal AG and FZ values were 0.42 cm³ (0.04–1.22) and 0.10 cm³ (0.02–0.47), respectively. The best-fit quantile regression models for fetal AG and FZ volumes as the function of GA were in first-degree models: AG = −0.937 + 0.041 × GA (R²=0.124) and FZ = −0.201 + 0.009 × GA (R²=0.127), respectively. We observed good intra-observer repeatability of fetal AG and FZ volumes, with an ICC of 0.996 and 0.989, respectively. We also observed good inter-observer repeatability, with an ICC of 0.972 and 0.966 for AG and FZ, respectively.

Conclusion: The reference ranges of AG and FZ volumes using 3DUS between 24 and 37 + 6 weeks of gestation were established and exhibited good repeatability.

Keywords:

• Fetal adrenal gland
• organ volume
• three-dimensional ultrasound

Declaration of interest

The authors declare no conflict of interest.