Forty percent of intermittent catheter (IC) users report pain during insertion and withdrawal [1] and 28% experience bleeding [2], both of which are likely consequences of IC-related microtrauma to the urethra. Increasing IC lubricity can reduce these issues. Traditionally, ICs with a hydrophilic polyvinylpyrrolidone (PVP) coating have been employed to help improve IC lubricity, however, coating dry-out is a common issue [3] that consequently requires increased withdrawal force that can lead to further complications. A novel approach to increasing IC lubricity is the use of integrated amphiphilic surfactant (IAS) technology, in which the hydrophilic head group of the surfactant migrates to catheter surface upon wetting to provide lubricity. The aim of the study was to compare urethral microtrauma caused by a PVP-coated IC and an IAS IC using an ex vivo porcine model.

It was hypothesized that the PVP-coated IC will cause more damage to the urethral surface than the IAS IC.

To investigate urethral microtrauma, a Zwick Universal Testing Machine was used to emulate patient IC use by subjecting the porcine urethra to 2 minutes of catheter contact with 3N of force.  Both catheters were prepared according to manufacture instructions.   

For direct fluorescence, the porcine urethra was stained with wheat germ agglutin (WGA) and Draq5. Tissue fluorescence was confirmed on a Keyence BZ-100 Microscope prior to IC contact. The ICs and tissues were cross-sectioned on a cryostat and imaged with Keyence BZ-100 fluorescence microscope. Intact catheter samples post-tissue contact were imaged using a Leica SP8 confocal microscope. 

For biochemical quantifications, the ICs post-tissue contact were placed in protease K for 2 hours at 50°C. For quantification of DNA, aliquots of the digest were placed on a NanoQuant plate and read on a Tecan Spark. To quantify sulfated glycosaminoglycan (sGAG) content, a Chondrex dimethyl methylene blue kit was used according to manufacturer instructions. Statistical analysis was performed where appropriate using GraphPad Prism 10. Significance indicates a p-value less than 0.05.

Direct fluorescence images of urethral tissue (n=6) and ICs (n=6) after IC-tissue contact showed greater disruption of the urethral surface in urethra that had contact with the PVP-coated IC compared to the IAS IC (Figure 1). More DNA and glycoproteins were observed on both intact and cross-sections of the PVP-coated IC compared to the IAS IC (Figure 1). Upon quantification, significantly more DNA and sulfated glycosaminoglycans were found on the PVP-coated IC than the IAS IC after contact with the urethral tissue.

Following 2 minutes of contact with urethral tissue (a typical time to self-catheterize), the PVP-coated IC removed more biological content from the urethra causing greater disruption of the uroendothelium than the IAS IC.  As the PVP-coated IC dry during use, the potentially adhesive surface may become sticky enough to dislodge portions of the mucosal layer and cells in the urethral lining from the tissue. Findings from this ex vivo model indicate that the IAS IC cause minimal alterations in the urethral lining compared to the PVP-coated IC.

In a controlled test examining urethral tissue and IC interaction, a PVP-coated IC led to more microtrauma in urethral tissue than an IAS IC. Use of new technologies, like an IAS, could improve IC user experience by reducing microtrauma and improving urethral health.

British Journal of Urology, 65(1), 1990, 20-23.
Neurourol. Urodyn., 40(8), 2021, 2008-2019.
Biotribology, 32, 2022, 100223.

Continence 12S (2024) 101593
DOI: 10.1016/j.cont.2024.101593