Foley catheters used for indwelling catheterisation are associated with several complications. There is need to objectively quantify performance of catheters to better understand limitations and improve designs. This study reports new approaches for quantifiable evaluation of urinary catheter performance.

A bladder model was created and geometrical analysis, computational fluid dynamical (CFD) and finite element analysis (FEA) were conducted on a typical Foley catheter.
A female lower urinary tract (LUT) model was created using standardised dimensions: 6 mm urethral diameter, 30 mm length, 26.1° bladder neck angle (1). The bladder was simplified to a cylindrical body with a conical bladder neck (Figure 1A). Catheter geometry (Teleflex Inc., USA) was created using computer-aided design software (SolidWorks 2022, Dassault Systèmes) and placed within the LUT model. Three key geometric parameters were analysed (Figure 1A): catheter height, residual volume, and immersed surface area. 
Flow rate and wall shear stress along the inner surface of the catheter were analysed using CFD. The flow area through the catheter in the LUT was imported into Ansys (Academic Student version, 2024 R1, Ansys Inc, USA). Boundary conditions (Figure 1B) include a pressure inlet (20 cmH2O) and outlet (0 cmH2O) and remaining surfaces were modelled as stationary walls.
The pushing of the bladder wall on the catheter during bladder emptying was simulated using FEA (Figure 1C). The Foley catheter model was imported into Ansys, and a 20×20×1.5 mm bladder strip was positioned above the catheter tip. A pressure force was applied gradually overtime, and von Mises stress was measured.

The geometric model resulted in a residual volume, catheter height and indwelling surface area of 196.2 ml, 52.9 mm and 340.7 mm2 respectively. Figure 2 shows the CFD and FEA simulations. The CFD model (Figure 2A) resulted in overall flow rate of 8 ml/s and minimum shear stress of 1.7 mPa located at the surface just above the catheter side hole. The FEA model (Figure 2B) produced a maximum von Mises stress of 28 kPa, located at the contact point of the catheter tip and bladder surface.

Computational modelling was able to quantify performance of the Foley catheter in several key metrics, identifying a large residual volume and low fluid outlet velocity and wall shear stresses above the side holes - these increase risk of biofilm and crystal growth (2). Lastly, catheter height and the pointed tip increase contact chance and von Mises stress, which risk bladder trauma (3).  Our results demonstrate a solid framework to evaluate catheter performance linked to important patient concerns.

We describe a computational framework for catheter performance evaluation, identifying areas for potential design improvement.

640-slice DVCT multi-dimensionally and dynamically presents changes in bladder volume and urine flow rate. Su Y, Fang K, Mao C, Xiang S, Wang J. Li Y. s.l. : Experimental and Therapeutic Medicine, 2018, Vol. 15.
The interplay between bacterial biofilms, encrustation, and wall shear stress in ureteral stents: a review across scales. Amado Pedro, Zheng Shaokai , Lange Dirk , Carugo Dario , Sarah L. Waters , Obrist Dominik , Burkhard Fiona , Clavica Francesco. s.l. : Frontiers in Urology, 2024, Frontiers in Urology, Vol. 3.
Damage Models for Soft Tissues: A Survey. Li, Wenguang. s.l. : Journal of Medical and Biological Engineering, 2016, Journal of Medical and Biological Engineering, Vol. 36.