Comparison between cold knife and laser urethrotomy for urethral stricture: a systematic review and meta-analysis of comparative trials

Safety and efficacy of lasers compared to cold knife in direct visual internal urethrotomy: a systematic review and Meta-analysis

Cold knife urethrotome was introduced in 1971 and it had an 80% success rate. New advancements in this field have shed light on the use of various lasers such as carbon dioxide, Nd: YAG, KTP, Argon, Ho: YAG, and excimer lasers. It has been observed that cold knife urethrotomy has a higher recurrence rate than laser urethrotomy, but the superiority of either treatment modality has not been established yet. Data were thoroughly searched through PubMed, Scopus, and clinicaltrials.gov. We also used clinicaltrials.gov for ongoing and published research. The data was analyzed via R studio version 2023.12.1 (oceanstorm). For dichotomous variables, Odds Ratio (OR) were used to pool data and standardized mean difference was used for continuous variables with 95% confidence intervals (CIs). A total of 14 studies including 1114 participants were included in this meta-analysis. The results of the combined analysis revealed significant relation with a mean difference of 0.99 (95% CI: 0.37; 1.62), and favored laser group. The overall results have shown the laser to have a significant favorable profile demonstrating a recurrence, Odds Ratio of 0.42 (95% CI:0.27;0.65). Patients with laser therapy had a lower risk of complication rate (OR 0.49, 95% Cl: 0.35; 0.67). All the findings obtained by the analysis in this study favour lasers significantly over the cold knife technique especially when mean Qmax, with recurrence and complications taken into account.

Clinical questions in the Japanese Urological Association's 2024 clinical practice guidelines for urethral strictures

Transurethral procedures such as direct vision internal urethrotomy and urethral dilation have been the traditional treatments for urethral strictures. However, transurethral procedures are associated with high recurrence rates, resulting in many uncured cases and prompting major international urological societies to recommend urethroplasty as the standard treatment owing to its high success rate. In contrast, many Japanese general urologists have little doubts about treating urethral strictures with transurethral treatment. Therefore, urethral stricture treatments in Japan are not in line with those used in other countries. To address this, the Trauma, Emergency Medicine, and Reconstruction Subcommittee of the Japanese Urological Association has developed guidelines to offer standardized treatment protocols for urethral stricture, based on international evidence and tailored to Japan's medical landscape. These guidelines target patients with a clinically suspected urethral stricture and are intended for urologists and general practitioners involved in its diagnosis and treatment. Following the Minds Clinical Practice Guideline Development Manual 2020, the committee identified eight critical clinical issues and formulated eight clinical questions using the "patient, intervention, comparison, and outcome" format. A comprehensive literature search was conducted. For six clinical questions addressed by the existing guidelines or systematic reviews, the level of evidence was determined by qualitative systematic reviews. Quantitative systematic reviews and meta-analyses were performed for the two unique clinical questions. The recommendation grades were determined using the Delphi method and consensus by the committee. These guidelines will be useful to clinicians in daily practice, especially those involved in the care of urethral strictures.

Comparison of laser versus cold knife visual internal urethrotomy in the treatment of urethral stricture (stricture length <2 cm): A systematic review and meta-analysis

PURPOSE

There is still controversy regarding the safety and efficacy of cold knife visual internal urethrotomy and laser incisions for the treatment of urethral stricture. This study aims to compare the results of postoperative long-term and short-term maximum urinary flow rates (Qmax), surgical time, postoperative complications, and 1-year recurrence rates between the cold knife and laser surgery.

METHODS

We searched databases including Embase, PubMed, Cochrane, and Clinical Trials.gov to identify relevant literature published in English up to September 2023. We used Stata to compare various parameters. This study is registered in PROSPERO (CRD42023471634). Nine comparative experiments were conducted, involving a total of 659 participants.

RESULTS

The laser group showed significantly better results compared to the cold knife group in terms of postoperative 12-month maximum urinary flow rate (mean differences [MD] 2.131; 95% [1.015, 3.249], P < .0001), postoperative bleeding (RR 0.277, 95% [0.079, 0.977], P = .046), and 1-year recurrence rate (RR 0.667, 95% [0.456, 0.976], P = .037). However, there were no significant differences in postoperative 6-month and 3-month Qmax, surgical time, urethral leakage complications, overall complications, and Visual Analog Scale (VAS) scores.

CONCLUSION

The current study results suggest that laser urethral incision has greater advantages in the long-term (12 months), 1-year recurrence rate, and bleeding complications compared to cold knife urethral incision in the treatment of urethral stricture (<2 cm). Therefore, laser urethral incision may be a better choice for patients with urethral stricture.

The thermal effect of lasers in urology: a review article

Lasers as a technology have a leading role in the modern urological treatment armamentarium. In this article, the application of lasers in different areas of urology is described. The major uses are in urolithiasis, benign prostatic enlargement (BPE), and management of many urological malignancies and other benign pathologies. Lasers have become an established treatment modality in urolithiasis, an acceptable alternative with the least side effect profile in BPE patients, and a novel and promising therapy in many other fields of Urology.

Impact of residual air trap in balloon on laser treatment of tubular tissue

OBJECTIVES

Tubular tissue, such as the bile duct and esophagus, often suffers from stenosis due to chronic inflammation or excessive contraction of smooth muscle. Laser treatment using a balloon catheter has been used to treat tubular tissue stenosis by mechanically expanding the tissue and irradiating laser light circumferentially on the tissue lumen. As the balloon is inflated with saline, the residual air in a delivery channel is often accumulated in the inflated balloon. Thus, the air trap may cause physical discontinuities at air-saline interface, leading to unpredictable and nonuniform photothermal interactions. The aim of the current study was to evaluate the optical-thermal effects of the air trap in the balloon on laser treatment of the tubular tissue by means of numerical simulations and experimental validations.

MATERIALS AND METHODS

A balloon-assisted diffusing applicator (BDA) was developed to inflate a balloon and deliver uniform and circumferential laser light. Before the balloon inflation, various numbers of deflations (0, 1, 2, 3, and 4) were applied to estimate the average amount of the air removed from the balloon. Ex vivo experiments using porcine liver duct were conducted with two deflation conditions (D0: no deflation for air trap and D3: three deflations for no air trap). The balloon was horizontally situated during laser irradiation to maintain the air trap at the same position in the balloon by minimizing gravity effect. Upon balloon inflation, 532 nm laser light was delivered through the BDA to the tissue (irradiance = 4 W/cm² ) at 10 W for 45 seconds to assess the optical-thermal effects of the air trap on the ductal tissue.

RESULTS

The size of the air trap was noticeably reduced with the number of deflations. The air trap volume in the balloon decreased to 0.5% of the total balloon volume after D3. Ex vivo results demonstrated that thicker coagulative necrosis (CN) for D0 near the air trap region in the tissue than bottom region that contact with saline, representing an asymmetric profile of CN in the tissue. D0 generated 17% thicker and nonuniform CN (overall CN thickness = 1.4 ± 0.7 mm), compared with D3 with no air trap (overall CN thickness = 1.2 ± 0.2 mm; p < 0.05). A threefold larger eccentricity (E) was found in D0 (49 ± 31%) than D3 (15 ± 13%; p < 0.001).

CONCLUSION

Both numerical simulations and experiments validated the effect of the air trap in a balloon on the distribution of CN in a tubular tissue during BDA-assisted laser treatment. Further in vivo studies will assess the current findings on the air trap for clinical translations of BDA-assisted laser treatment of tubular tissue stenosis.