Inclusion Criteria:

• Patients undergoing temporary Double-J ureteral stent insertion.
• Stent inserted for a standard urological indication, including ureteric stone disease, ureteral obstruction, postoperative drainage, or ureteral injury repair.
• Planned stent removal during the study follow-up period.
• Availability for clinical follow-up and specimen collection at insertion and removal.
• Provision of written informed consent.

Exclusion Criteria:

• Active urosepsis at the time of stent insertion.
• Permanent or intended long-term stenting outside the study framework.
• Concomitant nephrostomy tube or urinary diversion that may confound microbiological results.
• Known severe immunosuppression or neutropenia if expected to substantially alter colonization risk.
• Patients with incomplete baseline clinical data.
• Patients lost to follow-up or whose stent could not be retrieved for microbiological analysis.
• Refusal to participate.