Poster, Podium & Video Sessions
Presentation Authors: Anna Nagle*, Rachel Bernardo, Jary Varghese, Adam Klausner, John Speich, Richmond, VA
Introduction: Various methods are currently available to non-invasively quantify bladder volume. The goal of this project was to determine the most accurate method of quantifying bladder volume using 2D and 3D ultrasound techniques during urodynamics.
Methods: Nine female participants with OAB underwent an extended urodynamics procedure (Laborie Aquarius XT) while ultrasound images of the bladder were obtained using a 3D 6MHz transabdominal probe (GE Voluson E8). The bladder was filled with saline at a rate of 10% bladder capacity (based on an initial clinical fill) per minute while ultrasound images were captured once per minute. Bladder volume was estimated from 2D cross-sectional images in the sagittal and transverse planes assuming an ellipsoid geometry (Eqn 1, Vspheroid), assuming a shape in between an ellipsoid and a cube (Eqn 2, VBih by Bih et. al. 1998), and from the 3D ultrasound data obtained by tracing the bladder outline in six planes with GE's 4D View software (V3D, Fig. 1 panel A).
VSpheroid= π/6 (W*H*D) Eqn. 1
VBih=0.72*W*H*D=1.375*VSpheroid Eqn. 2
In Equations 1 and 2, W is the width (horizontal diameter) and H is the height (vertical diameter) in the sagittal direction and D is the depth in the transverse direction (horizontal diameter).
Results: VSpheroid was significantly lower than infused volume (VH2O) when compared by a paired t-test. VBih and V3D tended to be slightly, but not statistically, larger than VH2O (Fig. 1, Fig. 1 panel B).
Conclusions: The bladder shape cannot be assumed to be an ellipsoid in patients with OAB. Tracing the perimeter in several 3D imaging planes better accounts for the non-uniform geometry, providing a more accurate volume measurement. Volumes estimated by VBih or by tracing the bladder in 3D were not significantly different from VH2O, demonstrating that these are the most accurate methods of non-invasive assessment of bladder volume.
Source Of Funding: Support provided by NIH R01DK101719, VCU Presidential Research Quest Fund, and VCU Dean's Undergraduate Research Initiative.
Virginia Commonwealth University