RESUMO
INTRODUCTION: Encrustation and biofilm formation is a clinical problem occurring with indwelling urinary drainage devices routinely used in urological practice. AIM: To investigate the impact of ureteral stent surface on encrustation and biofilm formation. MATERIALS AND METHODS: Polyurethane stents of two manufacturers were examined using the scanning electron microscopy and scanning probe microscopy before use and three weeks after their initial ureteral placement in patients with no evidence of a urinary tract infection and urolithiasis. RESULTS: In one case, there were irregularities in the form of pyramids with a height of 0.15+/-0.02 m with a tendency to occur at regular intervals, forming ordered rows, with a density of 2.67 per 10 m2. The cross-sectional area of the irregularities in the probe displacement direction was 1.015 m, after use - 1.271 m (25.2% increase). In another case, pyramids with a height of 0.39+/-0.03 m (p<0.0001) were detected without the pattern of repetition in the form of a network, the density was 3.31+/-10 m2. The cross-sectional area of the irregularities was 1.158 and 2.29 m2, respectively (an increase of 97.8%). In the first case, after three weeks of stent placement, the pyramids increased twofold, were amenable to counting, the biofilms had the appearance of scattered "loose" formations. In the second case, there were polygonal conglomerates of salts dozens of times larger than the primary elements; biofilms had the appearance of well-formed massive layers. CONCLUSION: The nature of the ureteral stent surface exerts a direct independent effect on the degree of encrustation and the formation of biofilms.