XPS, SEM and EDX analysis of conditioning film deposition onto ureteral stents

Ureteral stents are commonly used in urology to drain urine from the kidney. An important complication arises when bacteria or encrustations adhere to the surfaces, causing infection and/or blockage of urine flow. It was hypothesized that upon exposure to urine flow, host elements are deposited as a conditioning film onto the surface of the materials, changing their characteristics. This was studied by x‐ray photoelectron spectroscopy analysis of stents removed from stone‐forming patients and in a stent incubated in vitro with urine. In addition to nitrogen being adsorbed, there was evidence of additional carbon compounds bound to hydroxyl and carboxyl and on some stent surfaces calcium and phosphorus were detected. When a stent was incubated in vitro with urine, nitrogen adsorbed along with a new type of carbon compound bound to hydroxyl. Scanning electron microscopy showed the presence of extensive bacterial biofilms, even after antibiotic therapy, and the existence of tears, erosions or abrasions in the stent surfaces within 2 weeks of implantation. Energy‐dispersive x‐ray analysis confirmed the presence of calcium, magnesium phosphorus and carbonate apatite crystals. These findings have important clinical implications.