Most studies of participants with stent-associated symptoms have either focused on stent factors, including differing stent materials, lengths, configurations, and drug-eluting stents, or investigated medications that target lower urinary tract symptoms. Despite these investigations, little progress has been made toward substantially mitigating stent-associated symptoms, or developing greater insights into mechanisms and/or predictive factors of more severe stent-associated symptoms. The Study to Enhance Understanding of Stent-associated Symptoms (STENTS) was a prospective observational cohort study of individuals undergoing clinically-indicated unilateral ureteroscopy with planned ureteral stent placement for treatment of a ureteral or renal stone. The observational cohort study also included a nested qualitative cohort. Participants completed a psychosocial profile and periodic symptom assessments, and urine specimens in addition to demographic, clinical, and operative characteristics. For adult participants, sensory testing and plasma specimens were also performed.

The primary objective of the study was to characterize associations between stent-associated symptoms (pain, urinary symptom, and interference domains) and participant demographic, psychosocial, clinical, and procedural factors based on cross sectional and longitudinal data.

The secondary objectives were to prospectively assess the association between central sensitization and stent-associated pain among adults using quantitative sensory testing (QST); to generate a preliminary multivariable prediction model for severe stent-associated pain and urinary symptoms; to compare assessment of stent-associated symptoms among different instruments, time frames, and key populations using existing measures of self-reported symptoms in the domains of pain, urinary symptoms, and interference; and to describe the participant-reported experiences of stent-associated symptoms in the short term (~7-10 days) following ureteroscopy for renal/ureteral stone, in the domains of pain, urinary symptoms, and interference.

Outcome measures included PROMIS Pain Intensity, PROMIS Pain Interference, BPI Pain Severity, BPI Pain Interference, USSQ-U, and LURN SI-10 scores, analyzed with mixed-effects linear models and various statistical tests to assess psychosocial factors, sex, age, urinary symptoms, ureteral instrumentation, and stone location. Multivariable linear models and Harrell’s C-statistic aimed at > 0.70 were used to model the outcome of severe stent-associated symptoms in pain, urinary symptoms, and interference domains. In addition, qualitative analyses using NVivo 12 software were conducted using systematic and verifiable methods of the nested qualitative cohort and exploratory questions.

Inclusion criteria:

• Informed consent/assent (parental consent for participants < 18 years of age)
• Age ≥ 12 years
• Clinical indication for retrograde unilateral ureteroscopy for renal and/or ureteral stone(s)

Exclusion criteria:

• Indwelling stent for any reason within 60 days before study enrollment (“pre-stenting” allowed if participant enrolled prior to stent placement with intent for later ureteroscopy)
• Bilateral ureteroscopy or bilateral stenting
• Concomitant percutaneous nephrolithotomy or shock wave lithotripsy
• Existing nephrostomy tube
• Pregnancy
• Spinal cord injury or neurologic disorder resulting in neuropathic bladder dysfunction (e.g., multiple sclerosis, spina bifida)
• Renal transplant recipient
• Bedridden patients (ECOG status 3 or 4)
• Unable to complete symptom assessment items due to language barrier, developmental delay, or cognitive impairment
• Anatomical urological abnormality including prior cystectomy, urinary diversion, horseshoe kidney, or congenital megaureter

The study found that older age, chronic pain conditions, prior severe stent pain, and depressive symptoms at baseline were linked to higher pain intensity after ureteroscopy with stent placement, while pain interference remained elevated over time. Preoperative hypersensitivity and central sensitization were associated with higher postoperative stent pain, suggesting a physiological basis for symptom variation. Predictive models identified factors such as female sex, younger age, higher BMI, baseline pain interference, chronic pain conditions, renal stone location, and anxiety as predictors of severe stent-associated symptoms. Participant experiences highlighted pain, discomfort, and psychological distress during and after stent removal, emphasizing the need for clear communication and patient-centered care. The impact of stent-associated symptoms on daily activities varied, with counseling recommended to help patients manage their symptom burden effectively.