Non-invasive methods to objectively characterize overactive bladder (OAB) and other forms of voiding dysfunction using real-time ultrasound are currently under development but require accurate and precise serial measurements of bladder volumes during filling. This study’s objective was to determine the most accurate and precise ultrasound-based method of quantifying serial bladder volumes during urodynamics (UD).
Twelve female participants with OAB completed an extended UD procedure with the addition of serial bladder ultrasound images captured once per minute. Bladder volume was measured using three ultrasound methods: (1) V spheroid: two-dimensional (2D) method calculated assuming spheroid geometry; (2) V bih: 2D correction method obtained by multiplying V spheroid by a previously derived correction factor of 1.375; and (3) V 3D: three-dimensional (3D) method obtained by manually tracing the bladder outline in six planes automatically reconstructed into a solid rendered volume. These volumes were compared to a control (V control) obtained by adding UD infused volume and the volume of estimated urine production.
Based on linear regression analysis, both V bih and V 3D were fairly accurate estimators of V control, but V 3D was more precise. V spheroid significantly underestimated V control.
Although the V bih and V 3D methods were more accurate than the more-commonly used V spheroid method for measuring bladder volumes during UD, the V 3D method was the most precise and could best account for non-uniform bladder geometries. Therefore, the V 3D method may represent the best tool required for the continued development of non-invasive methods to diagnose OAB and other forms of voiding dysfunction.