Effects of Topical Anesthetics on catheter-related bladder Discomfort in patients undergoing ureteroscopic litholapaxy: A Single-Center Randomized Controlled Study

This single-center randomized controlled study demonstrates that applying topical anesthetics, such as Tetracaine Hydrochloride or Oxybuprocaine Gel, significantly reduces catheter-related bladder discomfort and urethral pain in patients undergoing ureteroscopic litholapaxy, with the analgesic benefit being particularly pronounced in male patients.

The Gist

Imagine your bladder is a very sensitive, delicate balloon inside your body. When doctors perform a procedure to break up kidney stones (called ureteroscopy), they have to thread a thin tube through your urethra (the "plumbing pipe") and leave a small tube inside your bladder afterward to help you heal.

For many patients, this leftover tube feels like a constant, annoying itch or a burning sensation, making them feel like they desperately need to pee even when their bladder is empty. Doctors call this Catheter-Related Bladder Discomfort (CRBD). It's like having a tiny, invisible pebble stuck in your shoe that you can't take out; it distracts you and makes every step painful.

The Problem

The researchers wanted to know: Can we numb the "shoe" so the "pebble" doesn't hurt as much?

They tested a simple idea: Instead of just sliding the tube in with regular slippery gel (like Vaseline), what if they used special numbing gels (anesthetics) to coat the inside of the pipe before inserting the tube?

The Experiment

The team gathered 330 patients who were having kidney stone surgery. They split them into two main groups:

1. The "Regular Lubricant" Group (Control): These patients got the standard, non-numbing gel.
2. The "Numbing Gel" Group (Experimental): These patients got a special gel containing either Tetracaine or Oxybuprocaine. Think of these gels as "sleeping spray" for the nerves in the urethra and bladder.

They then measured how much pain and discomfort the patients felt at different times after waking up from surgery.

The Results: What Happened?

The study found some very clear patterns, which can be explained with a few analogies:

• The "Magic Spray" Worked: Patients who got the numbing gel felt significantly less pain and bladder irritation than those who just got the regular gel. It was like putting a thick, soft cushion inside a shoe instead of a thin sock.
• The "Gender Gap": Here is the most interesting part. The numbing gel worked wonderfully for men, but it didn't seem to help women much.
  • The Analogy: Imagine the urethra (the tube) as a hallway. In men, this hallway is long and has a few narrow turns (like a winding, narrow corridor). In women, it is very short and wide (like a short, open foyer).
  • Because the men's hallway is longer and has more "nooks and crannies," the numbing gel had more surface area to work on and more nerves to calm down. In women, the tube is so short that the gel might not have stayed in place long enough or covered enough area to make a huge difference.
• The "Two Brands" Test: The researchers used two different types of numbing gels. They found that both brands worked equally well. It didn't matter which "brand of sleeping spray" they used; both put the nerves to sleep effectively.
• The "Surgery Type" Test: It didn't matter if the doctor used a rigid (straight) tool or a flexible (bendy) tool to break the stones. The numbing gel helped reduce pain in both scenarios.

The Bottom Line

This study suggests that if a man is having kidney stone surgery and needs a tube left in his bladder, using a numbing gel beforehand is a smart move. It acts like a protective shield, turning a painful, burning experience into a much more comfortable one.

For women, the study suggests that while the gel is safe, it might not be the "magic bullet" for pain relief in this specific situation, and doctors might need to look for other ways to help female patients.

In short: Numbing the "plumbing pipe" before inserting the tube is a great way to stop the "itchy pebble" sensation, especially for men. It's a simple, cheap trick that could make a big difference in how patients feel after surgery.

Technical Summary

Title

Effects of Topical Anesthetics on Catheter-Related Bladder Discomfort in Patients Undergoing Ureteroscopic Litholapaxy: A Single-Center Randomized Controlled Study

1. Problem Statement

• Clinical Issue: Catheter-related bladder discomfort (CRBD) and urethral pain are prevalent complications following urinary catheterization, particularly after ureteroscopy lithotripsy (URSL). Incidence rates range from 47% to 90%, with 27–55% of cases classified as moderate to severe.
• Symptoms: CRBD manifests as a burning sensation, urinary urgency, frequency, lower abdominal distension, and pain, often mimicking overactive bladder (OAB). It leads to behavioral distress (e.g., attempts to remove the catheter) and hinders postoperative recovery.
• Gap in Knowledge: While various pharmacological interventions (anticholinergics, sedatives) exist, there is a notable lack of research specifically evaluating the efficacy of topical anesthetics (specifically Tetracaine Hydrochloride Gel and Oxybuprocaine Gel) in mitigating CRBD and urethral pain immediately following URSL procedures.

2. Methodology

• Study Design: A single-center, randomized, double-blind (assessor-blinded), placebo-controlled, parallel-group trial.
• Setting & Timeline: Conducted at Guangxi International Zhuang Medicine Hospital between September 20, 2024, and July 18, 2025.
• Participants:
  • Total Enrolled: 403 patients; Final Analyzed: 330 patients (160 Control, 170 Experimental).
  • Inclusion Criteria: Adults (18–85 years), ASA physical status 1–2, confirmed upper urinary tract stones, undergoing rigid or flexible URSL.
  • Exclusion Criteria: ASA ≥3, OAB history, liver dysfunction, drug allergies, or alternative treatments (ESWL, PCNL).
• Intervention Groups:
  • Control Group (n=160): Received standard lubrication with paraffin oil prior to catheterization.
  • Experimental Group (n=170): Received topical anesthesia 2 minutes prior to catheterization. This group was further subdivided:
    • Tetracaine Hydrochloride Gel Subgroup (n=82): 3g gel.
    • Oxybuprocaine Gel Subgroup (n=88): 30mg gel.
  • Procedure: All patients received an F16 silicone Foley catheter and an F6 ureteral stent.
• Outcome Measures:
  • Primary: CRBD Score (0–3 scale: 0=None, 1=Slight, 2=Moderate, 3=Severe).
  • Secondary: Urethral Pain Numerical Rating Scale (NRS) (0–10 scale).
  • Time Points: Measurements taken at T0 (extubation) through T6 (5.5 hours post-awakening).
• Statistical Analysis: SPSS 26.0 and R 4.4.2 used. Normal data analyzed via Student's t-test; non-normal data via Mann-Whitney U test. Significance set at $P < 0.05$.

3. Key Contributions

• Novel Application: This is one of the first studies to specifically evaluate the efficacy of Tetracaine and Oxybuprocaine gels for CRBD prevention specifically in the context of URSL with stent/catheter placement.
• Comparative Analysis: Directly compares two different ester-type local anesthetics against a placebo (paraffin oil) to determine if one offers superior relief.
• Subgroup Stratification: Provides granular data on how these interventions affect different demographics (gender) and surgical approaches (rigid vs. flexible ureteroscopy).

4. Results

• Overall Efficacy: The experimental group showed a statistically significant reduction in both CRBD scores and urethral pain NRS scores compared to the control group across all time points (T0–T6) ($P < 0.01$). The most pronounced effect was observed between T2 and T5.
• Gender Differences:
  • Male Patients: Significant reduction in both CRBD and pain scores in the experimental group ($P < 0.001$).
  • Female Patients: No statistically significant difference was observed between the experimental and control groups for females.
• Surgical Approach: The efficacy of the anesthetics was consistent regardless of whether the procedure was Rigid (R-URSL) or Flexible (F-URSL). No significant difference in outcomes was found between the two surgical types.
• Drug Comparison: No statistically significant difference was found between the Tetracaine Hydrochloride Gel subgroup and the Oxybuprocaine Gel subgroup; both were equally effective.
• Safety: No significant differences were observed in vital signs (HR, RR, SBP, DBP, MAP, SpO2) between groups, indicating the topical anesthetics did not induce adverse cardiovascular or respiratory effects.

5. Significance and Conclusion

• Clinical Implication: Topical application of Tetracaine Hydrochloride Gel or Oxybuprocaine Gel prior to catheterization is an effective, safe, and non-invasive strategy to reduce postoperative CRBD and urethral pain in patients undergoing URSL.
• Target Population: The intervention is particularly beneficial for male patients, likely due to anatomical differences (longer urethra, anatomical narrowings) which may make them more susceptible to catheter-induced trauma and pain.
• Future Directions: The study highlights the need for multicenter trials with larger sample sizes to validate these findings, particularly to investigate the lack of efficacy in female patients and to explore the impact of comorbidities like diabetes.
• Limitations: Single-center design, potential surgeon variability, and a relatively small sample size for certain subgroups (e.g., females, diabetic patients).

Conclusion: The study concludes that topical anesthesia is a valuable clinical tool for improving postoperative comfort and satisfaction, specifically recommending its use for male patients undergoing ureteroscopic stone removal.