Bladder Volume Calculator (Ultrasound)

Sonographic bladder volume is a geometric estimate: the product of length, height, and width multiplied by a correction coefficient that depends on bladder shape. Bih and colleagues derived coefficients of 0.89 (cuboid), 0.81 (ellipsoid), and 0.66 (triangular prism), with 0.72 as the best global coefficient when shape is not characterized; a spherical contour is approximated with the standard 0.52 ellipsoid constant. Accounting for shape reduced the mean estimation error from about 16.9% to 12.7% in that study, which is used here to give an approximate uncertainty range. Results should be read together with the images, since caliper placement, trabeculation, compression, and filling state all affect accuracy - particularly relevant for post-void residual assessment and radiotherapy preparation.