Presentation Authors: Andrew J Cohen*, San Francisco , CA, Nima Baradaran, Columbus, OH, Jorge Mena, San Francisco , CA, Daniel Krsmanovich, San Francisco, CA, Benjamin N Breyer, San Francisco , CA
Introduction: Computational fluid dynamics (CFD) has paradigm shifting potential to understand the physiological flow of fluids within the human body. This translational branch of engineering has already made important clinical impacts in the study of cardiovascular disease. We evaluated the feasibility and applicability of CFD for modeling the flow of urine in a urethral stricture model.
Methods: A CFD model was prepared using an idealized male genitourinary system. We created 16 hypothetical urethral stricture scenarios as a testbed. Standard parameters of urine such as pressure, temperature, and viscosity were applied as well as typical assumptions germane to fluid dynamic modelling. ABAQUS/CAE 6.14 with a direct unsymmetrical solver with standard (FC3D8) 3D brick 8Node elements was used for model generation.
Results: The average flow rate for urethral stricture disease, including 5, 10, and 15 French(Fr) strictures of varied length and location was 5.97 (IQR: 2.2-10.9 mL/s). The model predicted a flow rate of 2.88 mL/sec for a single 5 Fr stricture in the mid bulbar urethra when assuming all other variables constant. The model demonstrated increasing stricture diameter and the bladder pressure strongly impacted urine flow while the stricture location, length and sequence of multiple strictures had a weaker impact. Figure 1 summarizes velocity changes of flow with 15 Fr stricture. The length of the stricture had a moderate effect on the urine flow as the urine flow decreased to 2.25 mL/s, 1.23 mL/s, and 0.85 mL/s for a 1cm, 2cm and 4cm 5 Fr long stricture, respectively. In the case of multiple strictures, urine flow changed only 0.21mL/s when the sequence of stricture was changed from 5 Fr proximal to 10 Fr vs. 10 Fr proximal to 5 Fr.
Conclusions: We successfully created a CFD for an idealized male urethra with varied types of urethral strictures. Resultant flow rates are consistent with the literature. The accuracy of modelling increasing bladder pressures should be improved with future iterations. This technology has vast research and clinical potential in urology.
Source of Funding: Institutional Funds