One‐surgeon basketing technique for stone extraction during flexible ureteroscopy for urolithiasis: A comparison between novice and expert surgeons

Factors affecting the intraoperative calculi excretion during flexible ureteroscopy lithotripsy: an in vitro analysis

OBJECTIVE

To explore the parameters influencing intraoperative calculi excretion (ICE) during flexible ureteroscopy lithotripsy (fURL) using in vitro simulation experiments.

METHODS

3D-printed human kidney models were used to simulate the elimination of gravel during fURL. The factors influencing the ICE during fURL were analyzed by comparing the effects of different degrees of hydronephrosis (mild, moderate, and severe), surgical positions (supine and lateral position), ratios of endoscope-sheath diameter (RESD) (0.625, 0.725, and 0.825), gravel sizes (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm), and ureteral access sheaths (UASs) (traditional UAS and negative-pressure UAS) on ICE.

RESULTS

The impacts of various UAS, RESD, degree of hydronephrosis, surgical positions, and gravel sizes on ICE were all significant (p < 0.05). We found no evidence of multicollinearity for all the independent variables, and the linear regression equation fitted as ICE ( g / min ) = 0.102 + 0.083 ∗ UAS grade - 0.050 ∗ RESD grade - 0.048 ∗ hydronephrosis grade + 0.065 ∗ position grade - 0.027 ∗ gravel size grade (R2 = 0.569).

CONCLUSION

Employing negative-pressure UAS, smaller RESD, milder hydronephrosis, lateral position, and smaller gravel size contribute to improved ICE during fURL. Among them, the adoption of negative-pressure UAS had the most substantial effects.

What is the appropriate gravel size during ureteroscopy lithotripsy? An in vitro evaluation

To propose the suitable diameter of calculus debris produced during flexible ureteroscopy lithotripsy (fURL). A glass tube was used to simulate the stone excretion process during Furl. Different stone diameters (0.50-1.00 mm, 0.25-0.50 mm, and 0.10-0.25 mm) with three sizes of flexible ureteroscopy (fURS) (7.5Fr, 8.7Fr, and 9.9Fr) and ureteral access sheath (UAS) (12/14Fr) with or without negative pressure suction were employed in the experiment. The intraoperative calculi excretion (ICE) was recorded according to the stones discharged from the gap between fURS and UAS. The ICE raised significantly in thinner fURS and UAS due to the smaller Ratio of Endoscope-Sheath Diameter (RESD). The gravel size ≤ 0.25 mm was conducive to drainage with traditional UAS, while using fURS with negative-pressure UAS could significantly improve ICE. The gravel size ≤ 0.5 mm was conducive to expulsion. We clarify that ICE during ureteroscopy relates to RESD and negative pressure suction. The proper size of the stone fragment is critical in ensuring the expulsion during fURL, ≤ 0.25 mm in traditional UAS and ≤ 0.50 mm in negative-pressure UAS, respectively.

Innovations in Kidney Stone Removal

Urolithiasis is a common clinical condition, and surgical treatment is performed with different minimally invasive procedures, such as ureteroscopy, shockwave lithotripsy and percutaneous nephrolithotomy. Although the transition from open surgery to endourological procedures to treat this condition has been a paradigm shift, ongoing technological advancements have permitted further improvement of clinical outcomes with the development of modern equipment. Such innovations in kidney stone removal are new lasers, modern ureteroscopes, development of applications and training systems utilizing three-dimensional models, artificial intelligence and virtual reality, implementation of robotic systems, sheaths connected to vacuum devices and new types of lithotripters. Innovations in kidney stone removal have led to an exciting new era of endourological options for patients and clinicians alike.

Inhibition of sodium-glucose cotransporter 2 suppresses renal stone formation

BACKGROUND AND AIMS

Nephrolithiasis is a common renal disease with no effective medication. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, an anti-diabetic agent, have diuretic and anti-inflammatory properties and could prevent nephrolithiasis. Here, we investigated the potential of SGLT2 inhibition against nephrolithiasis using large-scale epidemiological data, animal models, and cell culture experiments.

METHODS

This study included the data of diabetic patients (n = 1,538,198) available in the Japanese administrative database and divided them according to SGLT2 inhibitor prescription status. For animal experiments, renal calcium oxalate stones were induced by ethylene glycol in Sprague-Dawley rats, and phlorizin, an SGLT1/2 inhibitor, was used for the treatment. The effects of SGLT2-specific inhibition for renal stone formation were assessed in SGLT2-deficient mice and a human proximal tubular cell line, HK-2.

RESULTS

Nephrolithiasis prevalence in diabetic men was significantly lower in the SGLT2 inhibitor prescription group than in the non-SGLT2 inhibitor prescription group. Phlorizin attenuated renal stone formation and downregulated the kidney injury molecule 1 (Kim1) and osteopontin (Opn) expression in rats, with unchanged water intake and urine volume. It suppressed inflammation and macrophage marker expression, suggesting the role of the SGLT2 inhibitor in reducing inflammation. SGLT2-deficient mice were resistant to glyoxylic acid-induced calcium oxalate stone formation with reduced Opn expression and renal damages. High glucose-induced upregulation of OPN and CD44 and cell surface adhesion of calcium oxalate reduced upon SGLT2-silencing in HK-2 cells.

CONCLUSION

Overall, our findings identified that SGLT2 inhibition prevents renal stone formation and may be a promising therapeutic approach against nephrolithiasis.

Primary impact of simultaneous use of double devices through one-working channel when performing flexible ureteroscope with ureteral access sheath for single ureteral stone: In bench and retrospective clinical study

OBJECTIVES

This study aimed to compare the simultaneous use of two devices versus a single device through a single working channel in flexible ureteroscopy using a ureteral access sheath for single ureteral stones.

METHODS

In a bench study, the time to (i) set laser fiber, (ii) exchange laser fiber and nitinol basket through working channel, and (iii) pull out the device from working channel were measured 10 times in each step. In a clinical study, 156 patients who underwent flexible ureteroscopy with a ureteral access sheath for a ureteral stone in middle and upper ureter between April 2019 and November 2021 were assessed. One device was used at a time for 79 patients (S-Group) and two were simultaneously used for 77 (D-Group). Surgical outcomes and complications were compared.

RESULTS

In the bench study, the mean time to change from laser fiber to basket and from basket to laser fiber through the working channel were 26.1 ± 3.7 s and 23.6 ± 2.0 s (p = 0.084), respectively, which were significantly longer than the laser setup time (p < 0.001). In the clinical study, although the stone-free rate was not significantly different between the groups (S-Group 89.8%, D-Group 93.5%; p = 0.412), the median operation time was significantly shorter (p < 0.001) and the rate of postoperative stenting was significantly lower (p = 0.002) in the D-Group. There were no significant between-group differences in intra- and post-operative complications.

CONCLUSION

The simultaneous use of two devices through a single working channel is safe and could help save the time needed to exchange the laser fiber and nitinol basket.

Efficacy of one-surgeon basketing technique for stone extraction during flexible ureteroscopy for urolithiasis

Objective: To evaluate the safety and efficacy of using one-surgeon basketing technique by a solo surgeon for stone extraction during flexible ureteroscopy (f-URS) for urolithiasis.

Patients and methods: This retrospective study enrolled patients with urinary calculus who underwent f-URS at two institutions in Japan between September 2014 and March 2020. A total of 100 patients were operated by one experienced surgeon using the one-surgeon basketing technique. With this approach, the f-URS apparatus was manipulated with the non-dominant hand and the basket catheter was manipulated with the dominant hand. We retrospectively examined the perioperative results, complications, and stone-free rate [with ‘stone free’ defined as ≤2 mm with kidney–ureter–bladder (KUB) at 1 month after f-URS] to estimate the safety and efficacy for comparison with the results of conventional retrieval basketing technique.

Results: Among our study population, the median stone size was 14 mm and median operative time was 74 min. A stone-free status was achieved in 91 patients (91%). The median stone fragmentation time was 15 min and stone retrieval time was 30 min. All included patients were treated using the one-surgeon basketing technique. Complications related to stone retrieval were identified in two patients (2%); the degree of ureteral injury was classified as Clavien–Dindo Grade IIIa.

Conclusion: The one-surgeon basketing technique is safe and effective for the extraction of stone fragments during f-URS for urolithiasis. This technique does not require assistance for basketing; therefore, f-URS with active retrieval basketing can be completed by a solo surgeon.

Abbreviations: BMI: body mass index; KUB: kidney–ureter–bladder; SFR: stone-free rate; UAS: ureteral access sheath; f-URS: flexible ureteroscopy

The impact of preoperative percutaneous nephrostomy as a treatment strategy before flexible ureteroscopy for impacted upper ureteral stones with hydronephrosis

Background

The treatment of impacted upper ureteral stones with hydronephrosis remains a challenge for urologists. The current study aimed to evaluate the impact of preoperative percutaneous nephrostomy (PNS) as a treatment strategy before flexible ureteroscopy (f-URS) of asymptomatic impacted upper ureteral stones with hydronephrosis.

Methods

This multicenter retrospective study included patients who underwent PNS (group A, n=61) and those who did not (group B, n=75) before f-URS for asymptomatic impacted upper ureteral stones with hydronephrosis. Impacted ureteral stones are defined as those that remain in one position for >2 months. Operative outcomes, including stone-free rate, operation time, postoperative hospital days, and complication rate, were evaluated.

Results

There were no significant differences in age, sex, and stone size between the two groups except in the grade of hydronephrosis, with group A having more cases of advanced hydronephrosis than group B. The stone-free rate was significantly higher in group A than in group B [95% vs. 77% (P=0.004)]. However, there were no significant differences between the groups in operation time [55 vs. 55 min (P=0.84)], postoperative fever [5% vs. 5% (P=1.00)], and postoperative hospital days [2 vs. 2 days (P=0.44)]. In group A, preoperative PNS placement was performed 4 days before f-URS, and the PNS was removed postoperatively on the same day of the f-URS. Additionally, subgroup analysis was performed in cases of grade 2 and 3 hydronephrosis. A total of 110 patients, 60 who underwent f-URS with PNS and 50 who underwent f-URS without PNS, were included. The stone-free rate was significantly higher in f-URS with PNS than in f-URS without PNS [95% vs. 76% (P=0.005)]. However, no significant differences were found between the groups in operation time, ureteral injury, postoperative fever, and postoperative hospital days.

Conclusions

At grade 2 or 3 hydronephrosis, preoperative PNS as a treatment strategy for a few days prior to f-URS for impacted upper ureteral stones improved the stone-free rate without increasing the operation time and postoperative length of hospital stay.