Holmium:YAG laser treatment of ureteral calculi: a 5-year experience

Super pulsed thulium fiber laser outcomes in retrograde intrarenal surgery for ureteral and renal stones: a systematic review and meta-analysis

BACKGROUND

Laser lithotripsy using a thulium fiber laser (TFL) has become an effective treatment option for small renal stones with low complication rates. TFL has a higher absorption coefficient, smaller fibers, and better pulse rate capability.

METHODS

We conducted a systematic review and meta-analysis to evaluate the published evidence regarding TFL's lithotripsy performance in retrograde intrarenal surgery (RIRS), for which we primarily assessed the outcomes of stone-free rate, operation time, and complications. We searched different databases from inception to April 2023. We assessed the methodological quality and risk of bias using the Cochrane Risk of Bias tool for randomized trials and the ROBINS-I tool for non-randomized studies. We used a random-effects model for meta-analysis and assessed heterogeneity using the I2 statistic.

RESULTS

Twelve published studies evaluated the efficacy of RIRS using a TFL for treating renal and ureteral stones. The meta-analysis revealed a predicted stone-free rate of 89.37% (95% CI: 83.93% to 93.12%), indicating that, on average, approximately 89.37% of patients achieved a stone-free state after treatment. The substantial heterogeneity among the studies was evident, as shown by a Q-value of 33.1174 and a p-value of 0.0003. The I2 value of 69.80% (95% CI: 25.91% to 92.02%) highlighted the proportion of variability attributed to genuine heterogeneity across the studies. Moreover, the H2 value 3.31 (95% CI: 1.35 to 12.53) indicated significant heterogeneity beyond random chance. The estimated overall effect size (logit-transformed) of 2.1289 was highly statistically significant (z = 8.7648, p < 0.0001) with a confidence interval of 1.6528 to 2.6049. The reported complications varied across studies, encompassing Clavien grade I-II complications in most cases, with a subset experiencing more severe Clavien grade III-V complications. Additionally, other studies noted a range of complications, such as haematuria, fever, transient creatinine elevation, and postoperative issues like bleeding, pain, and sepsis.

CONCLUSION

This meta-analysis suggests that RIRS using TFL is an effective and safe treatment option for renal and ureteral stones, with high stone-free and low complication rates. The included studies exhibited a low risk of bias and were of high quality. However, more extensive randomized controlled trials with extended follow-up periods are needed to investigate this technique's efficacy and safety.

Resistance of different guidewires to laser injury: an in-vitro experiment

BACKGROUND

In urology, lasers are used in a variety of endoscopic procedures such as ureteroscopy and retrograde renal surgery for stone fragmentation of urinary calculi and ablation of urothelial tumors. To perform these procedures, guidewires are used as a preliminary safe-mainstay for referencing the urinary tract. This study aims to determine the effect of two different lasers: holmium:YAG (Ho:YAG) and thulium:YAG (Tm:YAG) lasers on metal guidewires with PTFE coating (PTFE), nitinol guidewires with hydrophilic coating (Hydrophilic) and nitinol guidewires with hydrophilic listed coating (Zebra).

METHODS

Different combinations of frequency (5, 10 and 12 Hz) and energy per pulse (0.5, 1.5, and 2.6 J) of Ho:YAG laser were applied on the three kinds of guidewires in two experiments (50 J vs. 100 J of total energy). For the Tm:YAG laser three power levels (5, 35, and 70 W) with a total energy of 100 J were applied to the guidewires. The degree of damage (0 to 5) of the guidewire was assessed after each laser application.

RESULTS

A higher degree of injury of guidewires was related to higher values of total energy used for the Ho:YAG laser (P=0.036), and to higher values of power applied with the Tm:YAG (P=0.051). The most resistant guidewire to Ho:YAG laser energy was Zebra, followed by PTFE and Hydrophilic (P<0.001). With the Tm:YAG laser, PTFE guidewire appears to be the most resistant and the Hydrophilic the most fragile, although without reaching the statistical significance (P=0.223).

CONCLUSIONS

Both lasers revealed a harmful effect on the three tested guidewires. There was an association between the degree of injury and the amount of Ho:YAG laser energy and Tm:YAG laser power. The guidewire Zebra proved to be the safest when using Ho:YAG laser and the PTFE guidewire the most resistant to laser Tm:YAG. Further studies are necessary to confirm these results.

Impact of obesity on ureteroscopic laser lithotripsy of urinary tract calculi

PURPOSE

The treatment of urinary tract stones in obese patients may differ from the treatment of non-obese patients and their success rate varies. Our objective was to compare ureteroscopic treatment outcomes of ureteral and renal stones, stratified for stone size and location, between overweight, obese and non-obese patients.

MATERIALS AND METHODS

Charts were reviewed for 500 consecutive patients presenting at our institution for renal and ureteral stones. A total of 107 patients underwent flexible or semi-rigid ureteroscopy with Ho:YAG laser lithotripsy and met criteria for review and analysis.

RESULTS

Overall, initial stone-free rates were 91%, 97%, and 94% in normal, overweight and obese individuals respectively. When compared to non-obese patients, there were no significant differences (p value = 0.26; 0.50). For renal and proximal ureteral stones, the stone-free rate in overweight and obese individuals was 94% in both groups; and a stone-free rate of 100% was found for distal stones, also in both groups.

CONCLUSIONS

Ureteroscopic treatment of stones in obese and overweight patients is an acceptable treatment modality, with success rates similar to non-obese patients.

Ureteric guidewire damage by Holmium:YAG laser: preliminary results

Typically, guidewires are regularly used to provide access or act as a guide during laser lithotripsy. This may result in the tip of the fibre being in close proximity to the guidewire during the firing period and consequently, this could result in accidental damage to the guidewires during the procedure. To replicate this scenario, an experimental model was designed enabling accurate and reproducible positioning of the laser fibre relative to the guidewire. The guidewire was exposed to the laser energy for a range of typical settings used in the clinic. The results demonstrate that the guidewire is susceptible to laser energy damage, especially in close proximity to the fibre.

[Ostiolitholapaxy]

The authors developed a new, minimally invasive technique for the removal of impacted iuxtavesical ureteral stones, using nephroscope and a grasping forceps. They named this technique ostiolitholapaxy. The authors present their detailed technique and results. Between 1. 1. 1995 and 31. 12. 2006 48 operations were performed. In 41 cases the stones were removed successfully. In seven unsuccessful cases the stones were extracted by ureteroscopy. The authors worked up 41 successful cases presenting the steps and technical details of the procedure. Average stone size was 5,2 (3-12) mm. Male and female ratio was 23/18. In 19 patients local and in 22 patients spinal anaesthesia was performed. Among the patients who underwent local anaesthesia there were 13 (68,4%) female and 6 (31,6%) male patients. Average operating time was 8,5 (3,5-35) minutes. Mean follow-up time was 95,3 (2-143) months. The success rate of the procedure was 85,41%. There were no intraoperative complications. In the mentioned period no ureteral stricture and/or reflux-uropathy has developed. Due to the simplicity, efficacy of this technique and the fact that it can be performed even in local anaesthesia, this procedure can be useful in case of small symptomatic iuxtavesical stones as a quick and safe stone removal intervention.