Volume measurement is a fundamental technique in ultrasound used to determine the three-dimensional size of organs, masses, cysts, fluid collections, and other structures. The most common method uses the prolate ellipsoid formula: length multiplied by width multiplied by height multiplied by a correction factor (typically 0.523). Sonographers obtain measurements in two orthogonal (perpendicular) planes to capture all three dimensions. Volume measurement is applied routinely to many structures including the thyroid gland, prostate, bladder (for post-void residual), ovaries, gestational sac, and various masses. Accurate volume measurement requires consistent measurement technique, proper caliper placement, and imaging in true orthogonal planes. Modern ultrasound machines may also offer automated or 3D-based volume calculation tools that can improve accuracy and reproducibility.
Sonography Term