Risk Factors and Clinical Implications of Double-J Ureteral Stent Bacterial Colonization: A Prospective Cohort Study

Ureteral stents are indispensable in modern urology, but they are frequently complicated by bacterial colonization, biofilm formation, bacteriuria, and infectious morbidity.

Biofilm is clinically important because it promotes microbial persistence on the stent surface, reduces antimicrobial susceptibility, and may contribute to urinary tract infection (UTI) or even severe systemic infection in selected patients.

Prospective studies have shown that febrile ureteral stent-associated UTI occurs in a measurable proportion of patients and can progress to sepsis or septic shock in a subset.

More recent studies also confirm that colonization and resistance patterns vary by patient profile and stent dwell time.A major challenge in this field is that urine culture does not reliably exclude stent colonization.

Several studies have shown that a substantial proportion of patients with sterile urine still have colonized stents, meaning that urine testing alone may underestimate the burden of device-associated infection. In addition, the organisms recovered from stents are often more resistant than those isolated before stent insertion, which raises concern about delayed recognition and suboptimal empiric antibiotic choice in high-risk patients.

These findings support the need to study stent cultures and patient factors together rather than relying on urine culture alone.

The risk factors for bacterial colonization appear to be multifactorial, but the most consistently reported predictor is longer indwelling time. Other factors that have emerged across studies include diabetes mellitus, chronic kidney disease, pregnancy, prior urinary infection, prior catheterization, and albuminuria, although the strength of association is not uniform across all cohorts. Despite this, there is still limited prospective evidence integrating these predictors with clinical outcomes such as febrile UTI, symptom burden, and antimicrobial resistance.

Accordingly, we hypothesize that bacterial colonization of Double-J ureteral stents is associated with identifiable patient- and stent-related risk factors, especially prolonged indwelling time and metabolic or renal comorbidity, and that colonized stents are associated with clinically meaningful outcomes including bacteriuria, resistant organisms, and greater stent-related morbidity.

The significance of this study is that it may help refine patient counseling, improve timing of stent removal, and support targeted surveillance and antibiotic strategies in high-risk patients.

AIM OF THE STUDY To identify the risk factors associated with bacterial colonization of Double-J ureteral stents and to evaluate its clinical implications, including bacteriuria, UTI, antimicrobial resistance, and stent-related symptoms.

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.