Prospective, Randomized Trial Comparing Soft and Firm Ureteral Stents

Soft Vs. Firm Ureteral Stents: Symptoms Improvement Without Affecting Outcomes- a Prospective, Randomized Trial

The goal of this clinical trial is to evaluate whether ureteral stent type impacts stent-related symptoms and quality of life in patients undergoing ureteroscopy (URS) and stone lithotripsy for ureteral stones. The main questions it aims to answer are:

• Does a soft polymer stent reduce stent-related symptoms compared to a firm polymer stent?
• Does stent type affect intra- and postoperative complications? Researchers will compare patients receiving a soft polymer stent (Universa®, Cook Medical) to those receiving a firm polymer stent (Percuflex®, Boston Scientific) to determine if soft stents improve patient comfort and quality of life while maintaining a similar safety profile.

Participants will:

• Undergo URS and stone lithotripsy for ureteral stones.
• Be randomly assigned to receive either a soft or firm ureteral stent.
• Complete the Ureteral Stent Symptoms Questionnaire (USSQ) upon stent removal, 14 days after URS.

Study Design and Patient Selection

1. Study Period and Ethical Approval:

   • Conducted between July 2023 and July 2024 following institutional review board approval (SMC 0119-23).
   • Informed consent obtained from all participants.
   • Adhered to the Declaration of Helsinki.

2. Stent Types and Randomization:

   • Soft stent: Universa® (Cook Medical).
   • Firm stent: Percuflex™ Plus (Boston Scientific).
   • Randomization in a 1:1 ratio using asymptomatic maximal randomization.

Surgical Technique and Intervention Operative Team included three fellowship-trained endourologists.

Procedure Details:

• Ureteroscopy performed using standard 6.5/8.5Fr semi-rigid ureteroscope.
• Lithotripsy performed using a 120W Holmium:YAG laser (0.3 Joule, 40 Hertz, dusting technique).

Stent Placement was performed using a 0.038 Inch glide wire. 6Fr stents used, either soft or firm polymer material, according to randomization.

Proximal stent curls positioned in the upper calyx/renal pelvis; distal curls in the bladder.

Postoperative Care Stent removal was scheduled 2 weeks post-procedure, ans performed using a flexible cystoscope in the outpatient clinic.

Symptoms assesed using the Ureteral Stent Symptoms Questionnaire (USSQ) that was completed at the stent removal visit.

Statistical Analysis

1. Sample Size Calculation:

   • Based on a 3-point difference in USSQ index score between groups.
   • Assumed 5% type I error and 80% power.
   • Adjusted for a 10% dropout rate; target sample size: 140 patients.

2. Data Blinding:

   • Patients, data collectors, and analysts blinded to allocation.
   • Since blinding the surgeons to stent type was impossible, surgeons were not involved in data collection or analysis.

3. Analysis Methods:

   • Continuous variables: Mann-Whitney U test; median and IQR.
   • Categorical variables: Pearson's chi-square or Fisher's exact test; frequencies and proportions.
   • Multivariate linear regression for USSQ index and urinary domain scores.
   • Statistical significance set at p<0.05.
   • Analyses conducted using IBM SPSS v26.

This protocol ensures a rigorous and reproducible methodology for evaluating the impact of stent type on patient-reported outcomes following ureteroscopy and lithotripsy.

Inclusion Criteria:

• patients aged over 18 years
• ureteral stones measuring up to 2cm requiring URS and laser lithotripsy

Exclusion Criteria:

• pediatric patients
• bilateral stones requiring bilateral URS and laser lithotripsy,
• stone located in the renal pelvis or calyces,
• intra-operative complications of any kind,
• any residual stones during the procedure,
• ureteroscopies in which no stones were treated ("white ureteroscopy").