Comparison of suctioning and traditional ureteral access sheath during flexible ureteroscopy in the treatment of renal stones

Clinical efficacy analysis of tip‑flexible suctioning ureteral access sheath combined with disposable flexible ureteroscope to treat 2-4 cm renal stones

PURPOSE

This study aims to evaluate the clinical efficacy of using a tip‑flexible suctioning ureteral access sheath (TFS-UAS) in combination with a traditional ureteral access sheath (T-UAS) and a disposable flexible ureteroscope (DFU) for treating large renal stones (2-4 cm in diameter).

METHODS

We retrospectively collected clinical data from 238 patients who underwent retrograde intrarenal surgery (RIRS) at Ganzhou People's Hospital between January 2019 and October 2023. The study included 238 patients who met the inclusion criteria, with 125 in the observation group using TFS-UAS and 113 in the control group using T-UAS. We compared differences in the stone-free rate (SFR), complication rates, surgery duration, and average hospital stay between the two groups.

RESULTS

All 238 surgeries were successfully completed. The stone-free rates for the observation group at the first and thirtieth day post-surgery were 87.20% and 95.20%, respectively, whereas for the control group, the rates were 73.45% and 85.84%, showing statistically significant differences (P < 0.05). The overall complication rates were 1.6% for the observation group and 14.16% for the control group, also statistically significant (P < 0.001). The surgical times for stone removal were (101.17 ± 25.64) minutes for the observation group and (86.23 ± 20.35) minutes for the control group, with significant differences (P < 0.05).

CONCLUSION

Compared to T-UAS, combining TFS-UAS with DFU for treating renal stones of 2-4 cm diameter, although more time-consuming, resulted in higher SFRs and improved safety.

Application of 11/13Fr suctioning ureteral access sheath and 8.55Fr single-use digital flexible ureteroscope in one-stage flexible ureteroscopic lithotripsy: an initial experience of 900 cases

OBJECTIVES

To report our initial experience of one-stage flexible ureteroscopic lithotripsy(FURL) with 11/13Fr suctioning ureteral access sheath(UAS) and 8.55Fr single-use digital flexible ureteroscope(SDFU) in upper ureteral or renal calculi.

MATERIALS AND METHODS

We retrospectively collected the clinical data of 900 adult patients with upper ureteral or renal calculi treated by FURL with 11/13Fr suctioning UAS and 8.55Fr SDFU from January 2022 to April 2024. Demographics, peri- and postoperative outcomes were assessed.

RESULTS

In all, 40 of 940 cases(4.26%) failed to introduce UAS and required second-stage FURL because of ureterostenosis and were excluded. Mean stones size of the remaining 900 eligible cases was 1.68 ± 0.58 cm in greatest diameter. There were 228 cases of upper ureteral stone, 456 cases of renal stone and 216 cases of concomitant ureteral and renal calculi. The mean operation time was 52.20 ± 20.21 min and the postoperative hospital stay was 2.87 ± 1.37 days. The stone-free rate of 1 month postoperatively was 89.56% and only 2.44% of patients with residue underwent additional reoperation. The rate of postoperative fever, postoperative pain needing analgesic and slight ureteral mucosal injury were 5.11%, 8.22% and 7.78%, respectively. None of patient suffered from severe complications, such as sepsis or ureteral perforation.

CONCLUSION

It's practical and suitable for the vast majority of adult patients to undergo FURL in single session with 11/13Fr suctioning UAS without preoperative stenting. FURL with 11/13Fr suctioning UAS and 8.55Fr SDFU is feasible, reliable, safe, and efficient in the management of renal stone and upper ureteral stone.

Tip bendable suction ureteral access sheath versus traditional sheath in retrograde intrarenal stone surgery: an international multicentre, randomized, parallel group, superiority study

Background

Retrograde intrarenal surgery (RIRS) is the main treatments for upper urinary tract stones. The Ureteral Access Sheath (UAS) serves as a supplementary tool, facilitating direct kidney access during RIRS. High quality of evidence comparing tip bendable suction ureteral access sheath (S-UAS) with traditional UAS in RIRS for the treatment of renal and ureteral stones is lacking. The purpose of the study is to compare the efficacy and safety of S-UAS with traditional UAS in RIRS for the treatment of renal or ureteral stones ≤30 mm.

Methods

An international, multicenter, and superiority randomized controlled trial included 320 intention-to-treat patients across 8 medical centers in China, the Philippines, Malaysia and Turkey from August 2023 to February 2024. The inclusion criteria were patients ≥18 years old with renal or ureteral stones ≤30 mm. RIRS was performed using either S-UAS or traditional UAS. The primary outcome was the immediately stone-free rate (SFR). Secondary outcomes included SFR 3 months after operation, operating time, hospital stay, auxiliary procedures, complications (using the Clavien-Dindo grading system), and improvement in the Quality of Life (QoL) score. Differences between proportions [risk difference (RD)]/means [mean difference (MD)] and 95% confidence intervals (CI) were presented. This study is registered at ClinicalTrials.gov: NCT05952635.

Findings

The S-UAS group demonstrated a significantly higher immediately SFR (81.3% versus 49.4%; RD 31.9%; 95% CI 22.5%-41.7%; p = 0.004) compared to the traditional UAS group, as determined by the one-side superiority test. Additionally, the S-UAS group exhibited a higher SFR at 3 months post-operation (87.5% versus 70.0%; RD 17.5%; 95% CI 8.7%-26.3%; p < 0.001), lower postoperative fever rate (RD -11.9%; 95% CI -18.7% to -4.9%; p < 0.001), reduced use of stone baskets (RD -70.6%; 95% CI -77.8% to -63.5%; p < 0.001), and better QoL improvement (MD 7.25; 95% CI 2.21-12.29; p = 0.005). No statistically significant differences were observed in operation time, hospital stay, or the need for second-stage RIRS.

Interpretation

In RIRS for upper urinary tract stones ≤30 mm, S-UAS exhibited superior performance compared to traditional UAS, demonstrating higher SFR, reduced postoperative fever rate, and improved QoL outcomes. S-UAS emerges as a prudent and advantageous alternative to traditional UAS for RIRS.

Funding

National Natural Science Foundation of China and Guangdong Province, and Zhejiang Medicine and Health Program.

Recent advances in the treatment of renal stones using flexible ureteroscopys

Upper urinary tract stones are a common urological disease that can be treated by flexible ureteroscopy (FURS) through the natural urinary tract, in addition to extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy. The advantages of FURS are less trauma, faster recovery, and fewer complications, while its disadvantages include poor results of lithotripsy and stone extraction when dealing with larger stones, and prolonged operation time. Over the last two decades, the emergence of new technologies such as FURS combined with negative pressure suction, robot-assisted FURS, and artificially intelligent FURS, coupled with improvements in laser technology (the use of thulium fiber lasers and the invention of single-use flexible ureteroscopes (su-fURS) suitable for primary level application, have significantly increased the global adoption of FURS. This surge in usage holds a promising future in clinical application, benefiting a growing number of patients with renal calculi. Accompanied by changes in technical concepts and therapeutic modalities, the scope of indications for FURS is broadening, positioning it as a potential primary choice for urolithiasis treatment in the future. This review outlines the progress in employing FURS for the treatment of renal calculi in order to generate insights for further research.

Ureteroscopic lithotripsy with pressure-measuring ureteral access sheath for large ureteral stones

INTRODUCTION

To evaluate the safety and efficacy of ureteroscopic lithotripsy with pressure-measuring ureteral access sheath (PM-UAS) for large ureteral stones.

MATERIAL AND METHODS

A total of 258 consecutive patients with large ureteral stones ≥15 mm was enrolled. They were treated by ureteroscopic lithotripsy with PM-UAS in the oblique supine lithotomy position. The technology can precisely monitor and automatically control cavity pressure. The cavity pressure control value was set at -15 mmHg∼-5 mmHg. The cavity pressure limit value was set at 30 mmHg. Infusion flow rate was set at 100-200 ml/min. Postoperative data such as stone-free rate and complications were analyzed.

RESULTS

PM-UAS was successfully implanted in 225 patients at one stage. Eighteen cases of patients who had failed the first surgery were successfully treated with a second operation. Fifty-one cases with stones migrating up to the kidney were converted to flexible lithotripsy. The other 15 cases were converted to percutaneous nephrolithotomy due to significant ureteral stenosis. The operative time was 49.5 ± 11.2 min. The stone-free rates after one month and three months were 87.2% (212/243) and 94.2% (229/243), respectively. Complications from grade I to II were observed in 25(10.3%) patients. No other complications from grade III to V were noted.

CONCLUSION

The ureteroscopic lithotripsy with PM-UAS is safe and efficacious for large ureteral stones.

Fluid absorption during flexible ureteroscopy with intelligent control of renal pelvic pressure: a randomized controlled trial

PURPOSE

To investigate fluid absorption and its influencing factors during flexible ureteroscopy with intelligent control of renal pelvic pressure (RPP).

METHODS

A total of 80 patients with upper urinary tract calculi underwent flexible ureteroscopy with intelligent control of RPP by pressure-measuring ureteral access sheath and were randomly divided into four groups. The RPP of Groups A, B, and C were set at - 5, 0 and 5 mmHg, respectively. Conventional flexible ureteroscopy with uncontrolled pressure served as control Group D. The perfusion flow rate was set at 100 ml/min in the four groups, with 20 patients in each group. The fluid absorption was measured by 1% ethanol every 10 min. Operation time, stone-free rate, and complications were recorded.

RESULT

Seventy-three patients were finally included in the RCT. The general and preoperative data of the patients were comparable between the groups. The fluid absorption of Groups A, B, and C was significantly less than that of Group D (P < 0.01). Fluid absorption and operation time were positively correlated, and the correlation coefficients R were 0.864, 0.896, 0.918, and 0.947, respectively (P < 0.01). The fluid absorption of patients with vomiting, fever and ureteral injury was greater than that of patients without complications in the four groups (P < 0.01). In different groups, fluid absorption was greater in patients with ureteral injury Post-Ureteroscopic Lesion Scale (PULS) 1-3 than in noninjured patients (P < 0.01).

CONCLUSION

Flexible ureteroscopy with intelligent control of RPP effectively reduces the absorption of perfusion fluid. Operation time and ureteral injury are also key factors affecting perfusion fluid absorption.

REGISTRATION NUMBER AND DATE

NCT05201599; August 11, 2021.

Scoping Review of Experimental and Clinical Evidence and Its Influence on Development of the Suction Ureteral Access Sheath

The ureteral access sheath (UAS) has been a boon and a bane in flexible ureteroscopy (FURS), with its merits and demerits well established. Its design and dimensions were instrumental in reshaping the way flexible scopes were used and were key adjuncts to establishing retrograde intrarenal surgery (RIRS) as a standard of care in the endourological management of renal stones. With the ever-changing landscape of RIRS over the decades shaped by technological advancements in lasers and flexible scopes, the UAS has also continuously evolved. The utility of suction in endourology has recently changed the way RIRS is performed and is a game changer for FURS outcomes. With strong clinical and experimental evidence to support its use, the UAS has undergone a transformative change in the recent past, with its ability to monitor intrarenal pressure and provide a superior vacuum-cleaner effect that improves the trifecta of RIRS, namely an improved single-stage stone-free rate (SFR), minimise complications, and reduce reinterventions. Our comprehensive review outlines the key clinical and experimental evidence and traces the developments that were key to modifying the traditional UAS into a flexible and navigable suction ureteric access sheath (FANS) and highlights how the design and modifications, in turn, influence the ability to push the boundaries of RIRS.

Retrograde Intrarenal Surgery for Lithiasis Using Suctioning Devices: A Shift in Paradigm?

New suction endoscopes, ureteral access sheaths (UAS) and catheters aim to improve the efficacy of flexible ureteroscopy and optimize its safety. Suction UAS with non-flexible tips have shown promising results, especially in maintaining low intrarenal pressure, but also in removing small debris and reducing the "snow globe" effect. In addition, suctioning UAS with a flexible tip offers the advantage of being able to be navigated through the pyelocaliceal system to where the laser lithotripsy is performed. It can also remove small stone fragments when the flexible ureteroscope is retracted, using the Venturi effect. Direct in-scope suction (DISS) involves aspirating dust and small stone debris through the working channel of a flexible ureteroscope, thus regulating intrarenal pressure and improving visibility. Steerable aspiration catheters are other devices designed to increase stone clearance of the pyelocaliceal system. They are inserted under fluoroscopic guidance into every calyx after retraction of the flexible ureteroscope, alternating irrigation and aspiration to remove dust and small gravels. Combining flexible-tip suction UAS and the DISS technique may offer some advantages worth evaluating. The advantage of using these instruments to achieve a low intrarenal pressure was demonstrated. The true practical impact on the long-term stone-free status is a matter requiring further studies.

Ureteral stricture rate after endoscopic treatments for urolithiasis and related risk factors: systematic review and meta-analysis

PURPOSE

We aimed to accurately determine ureteral stricture (US) rates following urolithiasis treatments and their related risk factors.

METHODS

We conducted a systematic review and meta-analysis following the PRISMA guidelines using databases from inception to November 2023. Studies were deemed eligible for analysis if they included ≥ 18 years old patients with urinary lithiasis (Patients) who were subjected to endoscopic treatment (Intervention) with ureteroscopy (URS), percutaneous nephrolithotomy (PCNL), or shock wave lithotripsy (SWL) (Comparator) to assess the incidence of US (Outcome) in prospective and retrospective studies (Study design).

RESULTS

A total of 43 studies were included. The pooled US rate was 1.3% post-SWL and 2.1% post-PCNL. The pooled rate of US post-URS was 1.9% but raised to 2.7% considering the last five years' studies and 4.9% if the stone was impacted. Moreover, the pooled US rate differed if follow-ups were under or over six months. Patients with proximal ureteral stone, preoperative hydronephrosis, intraoperative ureteral perforation, and impacted stones showed higher US risk post-endoscopic intervention with odds ratio of 1.6 (P = 0.05), 2.6 (P = 0.009), 7.1 (P < 0.001), and 7.47 (P = 0.003), respectively.

CONCLUSIONS

The overall US rate ranges from 0.3 to 4.9%, with an increasing trend in the last few years. It is influenced by type of treatment, stone location and impaction, preoperative hydronephrosis and intraoperative perforation. Future standardized reporting and prospective and more extended follow-up studies might contribute to a better understanding of US risks related to calculi treatment.

The optimal ratio of endoscope-sheath diameter with negative-pressure ureteral access sheath: an in vitro research

PURPOSE

To maintain safe intrarenal pelvic pressure (IPP), the combination of flexible ureteroscope (fURS) and traditional ureteral access sheath (T-UAS) should maintain a basic rule that is the ratio of endoscope-sheath diameter (RESD) ≤ 0.75. However, the negative-pressure ureteral access sheath (NP-UAS) may break the rule of negative pressure suction. This study aimed to examine the effect of NP-UAS on IPP and flow rate (FR) with varying RESD.

METHODS

In a 3D-printed renal model, flexible ureteroscopy lithotripsy (fURL) was replicated. Six sizes of fURS paired with 12Fr T-UAS and NP-UAS resulted in six distinct RESDs of 0.63, 0.78, 0.87, 0.89, 0.90, and 0.91. While the irrigation pressure (IRP) was set between 100 and 800 cmH2O and the sucking pressure (SP) was set between 0 and 800 cmH2O, the IPP and FR were measured in each RESD.

RESULTS

NP-UASs can reduce the IPP and increase the FR at the same RESD compared to T-UASs. The IPP decreased with increasing SP with NP-UAS. When RESD ≤ 0.78, T-UAS and NP-UAS can maintain IPP < 40 cmH2O in most circumstances. When RESD = 0.87, it is challenging for T-UAS to sustain IPP < 40 cmH2O; however, NP-UAS can do so. When RESD ≥ 0.89, it is difficult to maintain an IPP < 40 cmH2O even with NP-UAS.

CONCLUSION

NP-UAS can decrease IPP and increase FR compared with T-UAS. To maintain a safe IPP, it is recommended that RESD < 0.85 when utilizing NP-UAS.

Comparison of traditional and suctioning ureteral access sheath during retrograde intrarenal surgery in the treatment of renal calculi

PURPOSE

This study aims to compare the efficiency and clinical outcomes between the suctioning ureteral access sheath (UAS) group and the traditional UAS group during retrograde intrarenal surgery (RIRS) for kidney stones and explore the impact of suctioning UAS on postoperative infectious complications.

METHODS

We retrospectively reviewed the clinical data of 162 patients with kidney stones who underwent RIRS with a traditional UAS (n = 74) or a suctioning UAS (n = 71) between March 2021 and May 2023.

RESULTS

The mean operative time in suctioning UAS group (39.03 ± 18.01 s) was significantly shorter than that (49.73 ± 20.77 s) in the traditional UAS group (P = 0.037). The mean postoperative hospital stay was significantly shorter in the suctioning UAS group (1.57 ± 0.82d) compared with the traditional UAS group (2.30 ± 1.6 2 d) (P = 0.032). The instant SFRs were significantly higher in the suctioning UAS group (88.73%) than in the traditional UAS group (75.68%) (P = 0.040). The overall SFR in suctioning UAS group (92.96%) was slightly higher than the traditional UAS group (85.14%). The incidence of overall complications was significantly higher in the traditional UAS group (35.14%) than in the suctioning UAS group (16.90%) (P = 0.013). In multivariate analysis, female patients (OR 0.053, P = 0.018), positive urine WBC (OR 10.382, P = 0.034), operative time > 60 min (OR 20.231, P = 0.032), and the application of traditional UAS (OR 0.042, P = 0.017) were independent risk factors associated with infectious complications.

CONCLUSION

We demonstrated that suctioning UAS provided a higher instant SFR and fewer postoperative infectious complications during RIRS, and patients with predictable risk factors for infectious complications could potentially benefit from the use of the suctioning UAS.

Flexible ureteroscopy with novel flexible ureteral access sheath versus mini-percutaneous nephrolithotomy for treatment of 2-3 cm renal stones

OBJECTIVES

To assess and compare the effectiveness and safety of flexible ureteroscopy (f-URS) with a novel flexible ureteral access sheath (f-UAS) versus mini-percutaneous nephrolithotripsy (mini-PCNL) in treating 2-3 cm renal stones.

METHODS

Retrospectively analyzed consecutive cases that underwent f-URS with f-UAS (12/14 Fr) from January 29, 2022, to November 30, 2022. Consecutive cases that underwent mini-PCNL (18 Fr) from June 5, 2021, to January 26, 2022, were selected as controls. The f-UAS is a novel device with a 10 cm anterior tip that passively bends along with the f-URS to enter the renal calyx. We analyzed demographic characteristics, stone parameters, operative time, stone-free rates (SFR), hospitalization time, and complication.

RESULTS

A total of 96 consecutive cases that underwent f-URS with f-UAS and 96 consecutive cases that underwent mini-PCNL were included in the study. There were no significant differences between the two groups in terms of operative time (p = 0.06), stone volume clearance (p = 0.533) and complete SFR (p = 0.266) on the first postoperative day or residual Stone after 1 month (p = 0.407). We observed a significantly shorter postoperative hospital stay (1.4 days vs. 2.1 days; p < 0.001) and a lower decrease in hemoglobin levels (0.39 g/dL vs. 0.68 g/dL; p < 0.001) in the f-UAS group. The mini-PCNL group had a significantly higher overall complication rate (13.5%) compared with the f-UAS group (5.2%; p = 0.048).

CONCLUSIONS

In the treatment of 2-3 cm renal stones, f-URS with a novel f-UAS may provide a superior alternative to mini-PCNL, potentially challenging its established status.

RIRS with FV-UAS vs. MPCNL for 2-3-cm upper urinary tract stones: a prospective study

To observe the efficacy and safety of retrograde intrarenal surgery (RIRS) combined with flexible vacuum-assisted ureteral access sheath (FV-UAS) and minimally invasive percutaneous nephrolithotomy (MPCNL) in patients with 2-3 cm upper urinary tract stones. A total of 160 patients with 2-3 cm upper urinary tract stones were prospectively randomized into 2 groups-80 in the FV-UAS group and 80 cases as control in the MPCNL group. The stone-free rates (SFRs) at different times (postoperative 1st day and 4th week) were considered as the primary outcome of the study. The secondary end points were operative time, hemoglobin decrease, postoperative hospital stay, and operation-related complications. There was no obvious difference between the two groups in patient's demographics and preoperative clinical characteristics (all P > 0.05). Postoperative data showed that mean decrease in hemoglobin level was less in FV-UAS group than that in MPCNL group (5.3 vs. 10.8 g/L, P < 0.001). Postoperative hospital stay in FV-UAS group was more shorten than that in MPCNL group (2.7 vs. 4.9 days, P < 0.001). There was no statistical significance between the two groups in SFRs during postoperative 1st day and 4th week (both P > 0.05). However, in terms of the rates of bleeding and pain, MPCNL group were both significantly higher than FV-UAS group (6.2 vs. 0.0%, P = 0.023; 16.2 vs. 2.5%, P = 0.003; respectively). Our study showed that RIRS with FV-UAS, a new partnership to treat 2-3 cm upper urinary tract stones, was satisfying as it achieved a high SFR rate and a low rate of complications. This method was safe and reproducible in clinical practice.

Comparison of novel flexible and traditional ureteral access sheath in retrograde intrarenal surgery

OBJECTIVES

To compare the efficiency and safety of a novel flexible ureteral access sheath (f-UAS) and traditional ureteral access sheath (UAS) during retrograde intrarenal surgery (RIRS).

PATIENTS AND METHODS

Between January 2022 and September 2022, a total of 152 consecutive cases with renal stones underwent RIRS with the f-UAS. Their outcomes were compared with those of another 152 consecutive cases undergoing RIRS with traditional UAS using a 1:1 scenario matched-pair analysis, with matching parameters including age and stone size. The f-UAS is a novel UAS with a 10-cm-long tube at the tip that can follow the bends of flexible ureteroscope (f-URS).

RESULTS

Baseline characteristics were found to be similar between the two groups. The f-UAS group demonstrated significantly higher SFR (76.3% vs. 7.2%; P < 0.001) at 1 day postoperatively and a higher clearance rate of stone volume (98.11% vs. 91.78%; P < 0.001). The f-UAS group also had lower total complications rate (9.9% vs. 22.4%; P = 0.003), lower incidence of fever (5.9% vs 11.9%; P = 0.001), shorter operative times (56.5 min vs. 59.9 min; P = 0.047), and lower usage rate of baskets (17.1% vs. 100%; P < 0.001). There was no significant difference in SFR at 1 month postoperatively (P = 0.627) and in the length of postoperative hospital stay between the two groups (P = 0.225).

CONCLUSION

Compared to the traditional UAS during RIRS, the f-UAS showed several advantages, including higher SFR at 1 day postoperatively, shorter operative times, lower incidence of complications, and less use of basket.

Experimental and clinical applications and outcomes of using different forms of suction in retrograde intrarenal surgery. Results from a systematic review

OBJECTIVE

To identify the latest advances in suction devices and evaluate their effect in Retrograde intrarenal surgery (RIRS) and ureteroscopy for stones.

BASIC PROCEDURES

A systematic literature search was performed on 4th January 2023 using Scopus, PubMed, and EMBASE. Only English papers were included; both pediatric and adult studies were accepted. Duplicate studies, case reports, letters to the editor, and meeting abstracts were excluded.

MAIN FINDINGS

Twenty-one papers were selected. Several methods have been proposed for suction use in RIRS, such as through the ureteral access sheath or directly to the scope. Artificial intelligence can also regulate this system, monitoring pressure and perfusion flow values. All the proposed techniques showed satisfactory perioperative results for operative time, stone-free rate (SFR), and residual fragments. Moreover, the reduction of intrarenal pressure (induced by aspiration) was also associated with a lower infection rate. Even the studies that considered kidney stones with a diameter of 20 mm or higher reported higher SFR and reduced postoperative complications. However, the lack of well-defined settings for suction pressure and fluid flow prevents the standardization of the procedure.

CONCLUSION

Aspiration device in the surgical treatment of urinary stones favours a higher SFR, reducing infectious complications, as supported by the included studies. RIRS with a suction system provided to be a natural successor to the traditional technique, regulating intrarenal pressure and aspirating fine dust.

The heat is on: the impact of excessive temperature increments on complications of laser treatment for ureteral and renal stones

OBJECTIVE

Technological advancements in the field of urology have led to a paradigm shift in the management of urolithiasis towards minimally invasive endourological interventions, namely ureteroscopy and percutaneous nephrolithotomy. However, concerns regarding the potential for thermal injury during laser lithotripsy have arisen, as studies have indicated that the threshold for cellular thermal injury (43 °C) can be exceeded, even with conventional low-power laser settings. This review aims to identify the factors that contribute to temperature increments during laser treatment using current laser systems and evaluate their impact on patient outcomes.

MATERIALS AND METHODS

To select studies for inclusion, a search was performed on online databases including PubMed and Google Scholar. Keywords such as 'temperature' or 'heat' were combined with 'lithotripsy', 'nephrolithotomy', 'ureteroscopy', or 'retrograde intrarenal surgery', both individually and in various combinations.

RESULTS

Various strategies have been proposed to mitigate temperature rise, such as reducing laser energy or frequency, shortening the duration of laser activation, increasing the irrigation fluid flow rate, and using room temperature or chilled water for irrigation. It is important to note that higher irrigation fluid flow rates should be approached cautiously due to potential increases in intrarenal pressure and associated infectious complications. The utilization of a ureteral access sheath (UAS) may offer benefits by facilitating irrigation fluid outflow, thereby reducing intrapelvic pressure and intrarenal fluid temperature.

CONCLUSION

Achieving a balance between laser power, duration of laser activation, and irrigation fluid rate and temperature appears to be crucial for urologists to minimize excessive temperature rise.

Comparison of traditional and novel tip-flexible suctioning ureteral access sheath combined with flexible ureteroscope to treat unilateral renal calculi

OBJECTIVES

To compare the safety and efficacy of novel tip-flexible suctioning ureteral access sheath (NTFS-UAS) and traditional ureteral access sheath (T-UAS) combined with flexible ureteroscope for treating unilateral renal calculi.

MATERIALS AND METHODS

The clinical data of 214 patients with unilateral renal calculi treated by NTFS-UAS (n = 102) and T-UAS (n = 112) combined with flexible ureteroscope from August 2021 to April 2022 were analyzed retrospectively. Demographic characteristics, stone-related parameters, operative time, stone-free rates (SFR), hospitalization time and complication rate (CR) were analyzed.

RESULT

No significant difference was observed between the two groups in terms of demographic characteristics, stone-related parameters, intraoperative CR, and hospitalization time. The operative time of NTFS-UAS group was significantly shorter than T-UAS group (55.25 ± 11.42 min vs. 59.36 ± 15.59 min; P = 0.028). The NTFS-UAS group obtained significantly higher SFR on 1 day postoperatively (86.3% vs. 75.0%; P = 0.038), and higher SFR on 30 days postoperatively than T-UAS group (91.2% vs. 81.3%; P = 0.037). The hemoglobin loss of NTFS-UAS group (- 0.54 ± 0.69 g/dl) was significantly lower than T-UAS group (- 0.83 ± 0.66 g/dl; P = 0.002). There was a significantly lower incidence of overall CR (11.8% vs. 22.3%; P = 0.041), and infectious CR (8.8% vs. 18.8%; P = 0.037) in the NTFS-UAS group.

CONCLUSION

Compared to T-UAS combined with flexible ureteroscope for treating unilateral renal calculi, NTFS-UAS had superiority in higher SFR on 1 day and 30 days postoperatively. Shorter operation time, lower hemoglobin loss, lower incidences of overall and infectious CR were observed in NTFS-UAS group.

REGISTRATION NUMBER AND DATE

ChiCTR2300070210; April 5, 2023.

Clinical application of novel integrated suctioning semi-rigid ureteroscopic lithotripsy

INTRODUCTION

Urinary calculi are frequently encountered in urology. Traditionally, the lack of a perfect water injection and drainage system means the observation field is affected during ureteroscopy. Here, we explored the effect and clinical value of a new integrated suctioning semi-rigid ureteroscopic lithotripsy (URSL) for treating ureteral calculi.

MATERIAL AND METHODS

A total of 180 patients were successfully enrolled in this study (60 in each group). Group A included patients who underwent a traditional semi-rigid URSL, group B included patients who underwent a suctioning semi-rigid URSL with a sheath being connected to a vacuum device, and group C included patients who underwent a new type of suctioning integrated rigid URSL with a novel designed ureteroscope.

RESULTS

In total, 164 cases of URSL were completed in one stage. Compared with group A, group C had a higher stone-clearance rate at 30 days postoperatively, shorter operation time, and fewer hospitalization days (p < .05); compared with group B, group C had a higher one-stage operation success rate, shorter operation time, and fewer hospitalization days (p < .05).

CONCLUSIONS

Comparatively, the new suctioning integrated semi-rigid URSL is advantageous for treating upper urinary calculi, considering the reduced operation time, length of hospital stay, and low invasiveness.

Flexible ureteroscopic lithotripsy with a suctioning ureteral access sheath for removing upper urinary calculi under local anesthesia

Objectives

We aimed to probe the safety and effectiveness of flexible ureteroscopic lithotripsy (FURL) with a suctioning ureteral access sheath (S-UAS) for removing upper urinary calculi under local anesthesia (LA).

Materials and methods

The clinical data of 56 patients with upper urinary calculi treated by FURL with an S-UAS under LA during the period between September 2019 and November 2022 were analyzed retrospectively. For LA, intramuscular pethidine (1.0-2.0 mg/kg) and phenergan (25 mg) were administered 30 min prior to surgery, and oxybuprocaine hydrochloride gel was administered through the urethra at the start of the surgery. The S-UAS and flexible ureteroscope were used for FURL. Demographic characteristics, stone-related parameters, and clinical outcomes were analyzed.

Result

A total of 66 procedures were performed successfully on 46 patients (Group A), who underwent unilateral surgeries, and on 10 patients (Group B) who underwent same-session bilateral surgeries. All 56 patients were operated upon without altering the anesthesia strategy, and none required additional analgesia. The mean stone sizes of the Group A and Group B patients were 20.24 ± 5.45 mm and 29.40 ± 3.89 mm, respectively. The mean operative times of the two groups were 53.04 ± 13.35 min and 90.00 ± 15.81 min, respectively. In Group A, the stone-free rates (SFRs) were 76.1% (35/46) and 85.1% (40/46) at postoperative day 1 and day 30, respectively. In Group B, the SFRs were 80.0% (16/20) and 85.0% (17/20), respectively. Four (8.7%) patients in Group A suffered complications such as fever, stent pain, urosepsis, and steinstrasse. In Group B, one (10%) patient suffered from fever.

Conclusion

FURL, combined with an S-UAS under LA, is a feasible option and provides satisfactory clinical outcomes for appropriately selected patients.

Optimal placement of flexible ureteral access sheath in retrograde intrarenal surgery

This study aims to explore the optimal location of flexible ureteral access sheath (f-UAS) in retrograde intrarenal lithotripsy (RIRS). RIRS model was built by AutoCAD 2011 software, and imported COMSOL 5.6 software to computer simulation. An RIRS model was constructed in vitro to analyze the distribution pattern of stone fragments and compare the weight of stone fragments carried out by the irrigation fluid when the f-UAS is in different positions. Computer simulation showed that the highest flow of irrigation fluid was in the channel of flexible ureteroscopy (f-URS) and in the lumen of f-UAS. From the f-URS to the renal collection system and then to the f-UAS, the velocity of irrigation fluid changes gradually from high-flow to low-flow and then to high-flow. When the f-URS and the f-UAS are at the same level, the irrigation fluid is always at a state of high flow during the process from f-URS to f-UAS. When the f-URS and the f-UAS are at the same level, it can increase the local intrarenal pressure (IRP) at the front of f-URS. The stone fragments are mainly sediment in the low-flow region of irrigation fluid. More stone fragments could follow the irrigation fluid out of the body when the tip of f-URS and the tip of f-UAS are at the same level (P < 0.001). The f-UAS should be brought closer to the stone in RIRS. And more stone fragments can be taken out of the body by the effect of irrigation fluid.

A Feasibility Study on Clinical Utility, Efficacy and Limitations of 2 Types of Flexible and Navigable Suction Ureteral Access Sheaths in Retrograde Intrarenal Surgery for Renal Stones

OBJECTIVE

To evaluate stone-free rate, device maneuverability, and complications after retrograde intrarenal surgery (RIRS) using 2 different sizes of flexible and navigable suction ureteral access sheaths (FANS).

METHODS

A retrospective analysis was performed for patients who underwent RIRS for renal stones of any size, number, and location between November 2021 and October 2022. Group 1 had FANS of 12 French. Group 2 had FANS of 10 French. Both sheaths have a Y-shaped suction channel. Tip of 10 French FANS has 20% more flexibility. Lithotripsy was achieved using either thulium fiber or high-power holmium lasers. A 5-point Likert scale was used to assess the performance of each sheath.

RESULTS

There were 16 patients in Group 1 and 15 patients in Group 2. Baseline demographics and stone parameters were similar. Four patients in Group 2 had the same session bilateral RIRS. Sheath insertion was successful in all renal units but one. Ten French FANS had a higher percentage of excellent scores for ease of use, manipulation, and visibility. Neither of the sheaths had an average or difficult rating for all evaluation scales. A fornix rupture requiring prolonged stenting occurred in group 2. All patients were discharged within 24 hours of surgery. One patient in each group visited the emergency department (analgesic treatment). There were no infectious complications. At 3 months, a computed tomography scan showed that the absence of residual fragments >2 mm was significantly higher in Group 2 (94.7% vs 68.8%, P = 0.01).

CONCLUSION

The 10 Fr FANS showed a higher stone-free rate. There was no infectious complication using both sheaths.

Cystine Stones: Developments in Minimally Invasive Surgery and Their Impact on Morbidity and Stone Clearance

Cystinuria is a rare genetic condition that is responsible for cystine stones. Besides stone recurrence, patients with cystine stones have reduced health-related quality of life, increased rates of chronic kidney disease and hypertension. Although lifestyle measures, medical therapy and close follow up are essential to reduce and monitor cystine stone recurrences, surgical intervention is frequently needed for most cystinuria patients. Shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy and active surveillance all have a role, and technological advances in endourology are vital in achieving a stone-free status and to prevent recurrences. The complexity of managing cystine stones necessitates a multidisciplinary team discussion, patient involvement and an individualised approach in a specialist centre for optimum management. Thulium fibre laser and virtual reality may have an increasing role in the future of cystine stone management.

A Pilot Study of a Novel Syphon Ureteral Access Sheath Shows Potential to Reduce Renal Pressures and Improve Irrigant Flow

OBJECTIVE

To describe a novel syphon ureteral access sheath (UAS) intended for use during flexible uretero-renoscopy (fURS). We aimed to report on a pilot study as well as intrarenal pressures (IRP) and irrigant flow volumes compared to traditional UAS.

METHODS

Patients undergoing routine fURS for single, <2cm intrarenal nephrolithiasis were identified, and written informed consent was obtained. Irrigation via the fURS was instilled through the novel 11/13 Fr UAS without (a proxy for a traditional UAS) and with the novel syphon box attached. Measured minute irrigant flow volume, steady state and bolus IRP were compared.

RESULTS

Ten participants (6 males and 4 females) were treated with the syphon UAS. All procedures were completed safely without intraoperative complications. The mean baseline IRP with and without the syphon was 18 vs 29 mmHG (P < .001, SD 4.0 vs 4.8). The mean minute irrigant flow volume with and without the syphon was 31 vs 21 ml (P < .001, SD 6.4 vs 3.3). The mean peak IRP following a 10 ml bolus with and without the syphon was 71 vs 104 mmHg (P = .03, SD 74 vs 59).

CONCLUSION

The described novel UAS is different from traditional devices by incorporating a syphon mechanism. This pilot trial demonstrates that the novel syphon UAS may hold clinical potential to reduce IRP and increase irrigant flow compared to traditional UAS. Firm conclusions about efficacy and safety require assessment of the device in a larger clinical trial.

Optimizing Outcomes in Flexible Ureteroscopy: A Narrative Review of Suction Techniques

OBJECTIVE

The aim of this review is to summarize the existing suction systems in flexible ureteroscopy (fURS) and to evaluate their effectiveness and safety.

METHODS

A narrative review was performed using the Pubmed and Web of Science Core Collection (WoSCC) databases. Additionally, we conducted a search on the Twitter platform. Studies including suctions systems in fURS were included. Editorials, letters and studies reporting intervention with semirigid ureteroscopy, PCNL and mPCNL were excluded.

RESULTS

A total of 12 studies were included in this review. These studies comprised one in vitro study, one ex vivo study, one experimental study and eight cohort studies. The Pubmed and WoSCC searches identified three suction techniques (Irrigation/Suctioning system with control of pressure, suction ureteral access sheath (sUAS) and direct in scope suction (DISS)), and the Twitter search identified four of them. The overall results showed that suction is an effective and safe technique that improves stone-free rates, reduces operative time and limits complication rates after fURS.

CONCLUSIONS

The use of suctioning during common endourological procedures has been shown to improve safety and efficacy in several indications. However, randomized controlled trials are needed to confirm this.

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.

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.

Comparison of Superpulse Thulium Fiber Laser vs Holmium Laser for Ablation of Renal Calculi in an In Vivo Porcine Model

Introduction and Objectives: We sought to compare the effectiveness and efficiency of the superpulse thulium fiber laser (sTFL to the holmium: yttrium-aluminum-garnet [Ho:YAG] laser for ureteroscopic "dusting" of implanted renal stones in an in vivo porcine model. Methods: Twenty-four porcine kidneys (12 juvenile female Yorkshire pigs) were randomized to Ho:YAG or sTFL treatment groups. Canine calcium oxalate stones were scanned with computed tomography to calculate stone volume and stone density; the stones were randomized and implanted into each renal pelvis via an open pyelotomy. In all trials, a 14F, 35 cm ureteral access sheath was placed. With a 9.9F dual lumen flexible ureteroscope, laser lithotripsy was performed using dusting settings: Ho:YAG 200 μm laser fiber at 16 W (0.4 J, 40 Hz) or sTFL 200 μm laser fiber at 16 W (0.2 J, 80 Hz). Lithotripsy continued until no fragments over 1 mm were observed. No stone basketing was performed. Throughout the procedures, intrarenal and renal pelvis temperatures were measured using two percutaneously positioned K-type thermocouples, one in the upper pole calyx and one in the renal pelvis. After the lithotripsy, the ureteropelvic junction was occluded, the kidneys were bivalved, and all residual fragments were collected, dried, weighed, and then measured with an optical laser particle sizer. Results: Implanted stones were similar in volume and density in both groups. Intraoperative collecting system temperatures were similar for both groups (all <44°C). Compared to Ho:YAG, sTFL ablated stones faster (9 vs 27 minutes, p < 0.001) with less energy expenditure (8 vs 26 kJ, p < 0.001), and a greater stone clearance rate (73% vs 45%, p = 0.001). After sTFL lithotripsy, 77% of the remaining fragments were ≤1 mm vs 17% of fragments ≤1 mm after Ho:YAG treatment (p < 0.001). Conclusions: In an in vivo porcine kidney, using dusting settings, sTFL lithotripsy resulted in shorter ablation times, higher stone clearance rates, and markedly smaller stone fragments than Ho:YAG lithotripsy.

Current evidence for suction in endourological procedures: comprehensive review of literature

PURPOSE OF REVIEW

To identify the latest advances on the utilization of suctioning devices in the surgical treatment of urinary stones.

RECENT FINDINGS

Advances are being made to incorporate suction and pressure control capabilities in percutaneous and ureteroscopic lithotripsy. Multiple retrospective studies and few prospective studies have shown that suctioning with minimally invasive percutaneous nephrolithotomy, commonly referred to as Super MiniPerc, can lead to better stone-free rates (SFR) and shorter operative time with lower incidence of infectious complications. Suctioning during retrograde intrarenal surgery (RIRS) has mainly been achieved through suctioning ureteral access sheath. Here as well, the incorporation of suction improved the SFR, but most importantly, reduced the risk of postoperative infectious complications.

SUMMARY

Theoretically suction in endourological procedures could facilitate stone debris removal and could reduce intrarenal pressure at the same time allowing for increased irrigation flow potentially decreasing operation time and infectious complications. These claims are supported in contemporary clinical studies, reporting superior SFR and reduced postoperative infectious complications in both percutaneous nephrolithotomy and RIRS.

The regular use of calcium channel blockers before flexible URS appears to facilitate primary UAS insertion: a retrospective study in a single center

PURPOSE

To evaluate the effect of regular use of CCB before flexible URS for successful primary UAS insertion.

MATERIALS AND METHODS

We retrospectively analyzed 209 patients who underwent flexible ureteroscopy (URS) for upper urinary tract calculi between Jan 2021 and Dec 2021. Patients were divided into two groups based on whether calcium channel blockers (CCB) were used (n = 72) or not (n = 137). The following parameters were collected: age, sex, height and weight, BMI, stone location, stone burden, number of stones, operation time, hospital stay, hospital readmission, post-operative fever, post-operative SIRS rate, Clavien-Dindo grade, hospitalization costs, successful primary UAS insertion. We compared the two groups using Student's t test, Mann-Whitney U test and χ² test for quantitative and categorical variables, respectively. A logistic regression model was used to identify predictive factors of UAS successful primary insertion.

RESULTS

Compared with the non-CCB group, the CCB group had a higher successful primary UAS insertion rate (97.2% vs.85.4%, p = 0.008), and a lower hospital readmission rate (2.8% vs.12.4%, p = 0.021). In multivariate analyses, the regular use of CCB was the only predictive factor of successful primary UAS insertion rate (OR 6.32, 95% CI 1.41-28.29, p = 0.016).

CONCLUSION

The regular use of calcium channel blockers (CCB) before flexible URS appears to facilitate ureteral access sheaths (UAS) primary insertion.

Single-use versus conventional reusable flexible ureteroscopes - an evaluation of the functional parameters

The purpose of single-use flexible ureteroscopes (su-fURS) was to overcome the limitations of conventional reusable ureteroscopes in terms of maneuverability and maintenance. We aimed to perform a systematic literature review on available su-fURS performance versus conventional reusable fURS focusing on clinical data. A systematic research using Pubmed was performed evaluating single-use fURS and reusable fURS in urinary tract stone disease, including prospective assessments and case series. This review aimed to provide an overview of single-use and disposable flexible ureteroscopes and to examine and compare their capabilities (deflection, irrigation, optical properties). We included 11 studies, where the single-use fURS were compared to the reusable fURS. The studies with single-use ureteroscopes included data on LithoVue (Boston Scientific), The Uscope UE3022 (Pusen, Zhuhai, China), NeoFlex-Flexible, (Neoscope Inc San Jose, CA), 23 YC-FR-A (Shaogang). For reusable ureteroscopes, data were included on three models, two digital (Karl Storz Flex-XC and Olympus URF-Vo) and one fiber optic (Wolf-Cobra). There were no significant differences in stone-free rate, procedure duration, or functional capabilities between single-use fURS and reusable fURS. The systematic literature review analyzed operative time, functional capabilities, stone-free rates, and postoperative complications of the ureteroscopes, and a special chapter about renal abnormalities to emphasize that they are a good choice having a high proportion of stone-free rates and few risks, particularly in treating difficult-to-access calculi. Single-use fURS demonstrate a comparable efficacy with reusable fURS in resolving renal lithiasis. Further studies on clinical efficacy are needed to determine whether single-use fURS will reliably replace its reusable counterpart.

Best Practice in Interventional Management of Urolithiasis: An Update from the European Association of Urology Guidelines Panel for Urolithiasis 2022

PURPOSE

The European Association of Urology (EAU) has updated its guidelines on clinical best practice in urolithiasis for 2021. We therefore aimed to present a summary of best clinical practice in surgical intervention for patients with upper tract urolithiasis.

MATERIALS AND METHODS

The panel performed a comprehensive literature review of novel data up to May 2021. The guidelines were updated and a strength rating was given for each recommendation, graded using the modified Grading of Recommendations, Assessment, Development, and Evaluations methodology.

RESULTS

The choice of surgical intervention depends on stone characteristics, patient anatomy, comorbidities, and choice. For shockwave lithotripsy (SWL), the optimal shock frequency is 1.0-1.5 Hz. For ureteroscopy (URS), a postoperative stent is not needed in uncomplicated cases. Flexible URS is an alternative if percutaneous nephrolithotomy (PCNL) or SWL is contraindicated, even for stones >2 cm. For PCNL, prone and supine approaches are equally safe. For uncomplicated PCNL cases, a nephrostomy tube after PCNL is not necessary. Radiation exposure for endourological procedures should follow the as low as reasonably achievable principles.

CONCLUSIONS

This is a summary of the EAU urolithiasis guidelines on best clinical practice in interventional management of urolithiasis. The full guideline is available at https://uroweb.org/guidelines/urolithiasis.

PATIENT SUMMARY

The European Association of Urology has produced guidelines on the best management of kidney stones, which are summarised in this paper. Kidney stone disease is a common condition; computed tomography (CT) is increasingly used to diagnose it. The guidelines aim to decrease radiation exposure to patients by minimising the use of x-rays and CT scans. We detail specific advice around the common operations for kidney stones.

High stone-free rate immediately after suctioning flexible ureteroscopy with Intelligent pressure-control in treating upper urinary tract calculi

Background

The retrospective observational study aimed to evaluate the safety and efficacy of suctioning flexible ureteroscopy with Intelligent pressure-control (SFUI) on treating upper urinary tract calculi in a large cohort.

Methods

Between July 2020 and August 2021, 278 patients with upper urinary tract calculi who underwent SFUI in our hospital were enrolled. Outcomes were stone-free rate (SFR) in one session and one-month after SFUI treatment, and complications scored by the Clavien-Dindo classification.

Results

A total of 310 kidneys underwent SFUI were included. The median surgery time was 75 min (ranged 60–110 min). One session and one-month SFRs were 80.65% and 82.26%, respectively. The one-session SFR was ≧ 87% in patients with Guy’s stone score of Grade I among stone size < 40 mm. Risk factors for unsuccessful stone-free in one session were stone history (adjusted odds ratio (aOR): 2.39, 95% confidence interval (CI): 1.21–4.73), stone size of 40–49 mm (aOR: 4.37, 95% CI: 1.16–16.45), Guy’s stone score ≧ Grade II (Grade II, aOR: 3.54, 95% CI: 1.18–10.59; Grade III, aOR: 10.95, 95% CI: 2.65–45.25). The incidence of Clavien-Dindo grade II-III complication was 3.26%. Complication is associated with Guy’s stone score III (aOR: 22.36, 95% CI: 1.81–276.36).

Conclusion

SFUI shows good safety and efficiency on treating upper urinary tract calculi. Patients with stone size < 40 mm or Guy’s stone score of Grade I have a high chance to reach stone-free after SFUI treatment.

Technique, Feasibility, Utility, Limitations, and Future Perspectives of a New Technique of Applying Direct In-Scope Suction to Improve Outcomes of Retrograde Intrarenal Surgery for Stones

Retrograde intrarenal surgery (RIRS) is accepted as a primary modality for the management of renal stones up to 2 cm. The limitations of RIRS in larger volume stones include limited visualization due to the snow-globe effect and persistence of fragments that cannot be removed. We describe a new, simple, cost-effective modification that can be attached to any flexible ureteroscope which allows simultaneous/alternating suction and aspiration during/after laser lithotripsy using the scope as a conduit to remove the fragments or dust from the pelvicalyceal system called direct in-scope suction (DISS) technique. Between September 2020 and September 2021, 30 patients with kidney stones underwent RIRS with the DISS technique. They were compared with 28 patients who underwent RIRS with a 11Fr/13Fr suction ureteral access sheaths (SUASs) in the same period. RIRS and laser lithotripsy were carried out traditionally with a Holmium laser for the SUAS group or a thulium fiber laser for the DISS group. There was no difference in age, gender, and history of renal lithiasis between the two groups. Ten (40%) patients had multiple stones in the DISS groups, whilst there were no patients with multiple stones in the SUAS group. Median stone size was significantly higher in the DISS group [22.0 (18.0−28.8) vs. 13.0 (11.8−15.0) millimeters, p < 0.001]. Median surgical time was significantly longer in the DISS group [80.0 (60.0−100) minutes] as compared to the SUAS group [47.5 (41.5−60.3) minutes, p < 0.001]. Hospital stay was significantly shorter in the DISS group [1.00 (0.667−1.00) vs. 1.00 (1.00−2.00) days, p = 0.02]. Postoperative complications were minor, and there was no significant difference between the two groups. The incidence of residual fragments did not significantly differ between the two groups [10 (33.3%) in the DISS group vs. 10 (35.7%) in the SUAS group, p = 0.99] but 10 (33.3%) patients required a further RIRS for residual fragments in the DISS group, whilst only one (3.6%) patient in the SUAS group required a subsequent shock wave lithotripsy treatment. Our audit study highlighted that RIRS with DISS technique was feasible with an acceptable rate of retreatment as compared to RIRS with SUAS.

Ureteral Access Sheaths and Its Use in the Future: A Comprehensive Update Based on a Literature Review

Ureteral access sheaths (UASs) are part of urologist’s armamentarium when performing retrograde intrarenal surgery (RIRS). Recently, the world of RIRS has changed dramatically with the development of three game-changers: thulium fiber laser (TFL), smaller size single use digital flexible ureterosopes and intraoperative intrarenal pressure (IRP) measurement devices. We aimed to clarify the impact of UASs on IRP, complications and SFRs and put its indications in perspective of these three major technological improvements. A systematic review of the literature using the Medline, Scopus and Web of Science databases was performed by two authors and relevant studies were selected according to PRISMA guidelines. Recent studies showed that using a UAS lowers IRP and intrarenal temperature by increasing irrigation outflow during RIRS. Data on the impact of a UAS on SFRs, postoperative pain, risk of infectious complications, risk of ureteral strictures and risk of bladder recurrence of urothelial carcinoma after diagnostic RIRS were inconclusive. Prestenting for at least one week resulted in ureteral enlargement, while the influence of pre-operative administration of alpha-blockers was unclear. Since TFL, smaller single use digital ureteroscopes and devices with integrated pressure-measuring and aspiration technology seemed to increase SFRs and decrease pressure and temperature related complications, indications on the use of a UAS may decrease in the near future.

Novel syphon ureteric access sheath has the potential to improve renal pressures and irrigant flow

OBJECTIVE

To describe a novel syphoning ureteric access sheath (UAS) intended for use during flexible ureterorenoscopy (URS). We aimed to assess if in vitro it could reduce intrarenal pressure (IRP) and increase irrigant flow compared to traditional UASs.

MATERIALS AND METHODS

A validated phantom kidney with fibre optic pressure sensing capabilities was used to assess the IRP. Standardised 80 cmH₂ O irrigation via a ureterorenoscope was instilled through traditional UASs (11/13 and 12/14 F) and compared to the novel 11/13-F syphoning UAS. The measured minute volume, calculated hourly flow volume, and steady state IRP were compared.

RESULTS

The traditional 11/13 and 12/14-F UASs had statistically poorer irrigant flow than the novel syphoning UAS, at 19.3 vs 29.3 mL/min (P < 0.001) and 22.7 vs 29.3 mL/min (P = 0.002), respectively. The steady state IRP was 20 mmHg for the traditional 11/13 F and 13 mmHg for the 12/14 F compared to 0 mmHg for the novel UAS.

CONCLUSION

The described novel UAS is different from traditional devices by incorporating a syphon mechanism. Our in vitro assessment demonstrates that the novel UAS holds clinical potential to reduce IRP while allowing a significant increase in irrigant flow compared to larger diameter traditional UASs.

Application of Suctioning Ureteral Access Sheath during Flexible Ureteroscopy for Renal Stones Decreases the Risk of Postoperative Systemic Inflammatory Response Syndrome

Purpose

To clarify the efficiency and outcomes of suctioning ureteral access sheath (UAS) during flexible ureteroscopic lithotripsy (fURL) for the management of renal stones.

Methods

Between January 2017 and January 2019, a total of 444 patients with renal stones undergoing fURL were divided into suctioning UAS and nonsuctioning UAS groups. The outcomes of patients in both groups were compared using a matched-pair analysis (1 : 1 scenario). Furthermore, a directed acyclic graph (DAG) was drawn to guide the multivariate logistic regression model and analyze the protective effect of suctioning UAS on the incidence of postoperative systemic inflammatory response syndrome (SIRS).

Results

Before propensity score matching, significant differences were observed between the two groups in blood white cell counts, urine white cell counts, preoperative fever, preoperative indwelling stents, and laterality (P < 0.05). Eighty-one patients in the suctioning UAS group were successfully matched with 81 patients in the nonsuctioning group. The stone-free rate (SFR) on postoperative day 1 after fURL in the suctioning group was higher than that in the nonsuctioning group (86.4% vs. 71.6%; P=0.034), whereas it was comparable between the two groups 1 month after the surgery (88.9% vs. 82.7%; P=0.368). The incidence of postoperative fever or SIRS was lower in the suctioning group (fever: 3.70% vs. 14.8%; P=0.030; SIRS: 1.23% vs. 12.3%; P=0.012). However, the operative duration was similar in both groups (mean (SD)) (72.9 (28.1) min vs. 80.0 (29.5) min; P=0.121). The result of the multivariate logistic regression model guided by DAG revealed that the application of nonsuctioning UAS (odds ratio: 5.28 [1.38-35.07], P=0.034) during fURL was associated with postoperative SIRS.

Conclusions

The application of suctioning UAS during fURL was associated with higher SFR on day 1 after surgery and a lower incidence of postoperative fever or SIRS.

Novel flexible vacuum-assisted ureteral access sheath(FV-UAS) can actively control intrarenal pressure and obtain a complete stone-free status

OBJECTIVES

To compare the safety and effectiveness of a novel flexible vacuum-assisted ureteral access sheath (FV-UAS) and traditional ureteral access sheath (UAS) in simulating retrograde intrarenal surgery (RIRS).

MATERIALS AND METHODS

Amanometric model was established in porcine kidneys to observe the change inintrarenal pressure in the FV-UAS and traditional UAS groups at different irrigation fluid velocities of 30 ml/min, 50 ml/min, 80 ml/min, and 100 ml/min. Establish a kidney stone model (with 0.2 g, dry, ≤ 5 mm stones) to simulate RIRS. A total of 20 porcine kidneys wererandomly numbered from 1 to 20 (FV-UAS group, 1-10; traditional UAS group, 11-20). The stone volume clearance rate and operation time were compared between the two groups. [" Stone volume clearance rate= (1-(residual stone volume)/(preoperative stone volume))×100%" )]. Stones volume was obtained by computed tomography (CT) preoperatively and postoperatively.

RESULTS

FV-UAS can follow flexible ureteroscopy (f-URS) to cross the ureteropelvic junction (UPJ) and into the renal pelvis and calyces. FV-UAS can actively make intrarenal pressure (IRP) less than 10 cmH2O by adjusting the negative values atdifferent irrigation fluid velocities. The mean residual stone volume of the FV-UAS vs. traditional UAS groups was33.7 mm3 vs. 92.5 mm3 (P = 0.017). The mean stone volume clearance rates of the FV-UAS vs. traditional UAS groups were 98.5 % and95.9 %, respectively (P = 0.017). Seven cases achieved complete stone-free status in the FV-UAS group. All patients hadresidual fragments postoperatively in the traditional UAS group.

CONCLUSIONS

FV-UAS can follow f-URS to cross the UPJ and into the renal pelvis and calyces, avoiding the interference of UPJ in controlling IRP. FV-UAS can actively control the IRP to be reduced to the desired range by adjusting the negative value under any irrigation fluid velocity. FV-UAS close to the stone can achieve complete stone-free in RIRS.

The clinical outcomes of flexible ureteroscopy and laser lithotripsy (FURSL) for treatment of the upper urinary tract calculi

PURPOSE

To evaluate efficacy and safety of flexible ureteroscopy and laser lithotripsy (FURSL) for treatment of the upper urinary tract calculi.

METHODS

We retrospectively analyzed 784 patients who underwent FURSL between January 2015 and October 2020 in our unit. All patients were preoperatively evaluated with urine analysis, serum biochemistry, urinary ultrasonography, non-contrast computed tomography and intravenous urography. The procedure was considered as successful in patients with complete stone disappearance or fragments < 4 mm on B ultrasound or computed tomography. The operative parameters, postoperative outcomes and complications were recorded and analyzed respectively.

RESULTS

The average operative time and postoperative hospital stay were 46.9±15.8 min and 1.2±1.1 days, respectively, among 784 patients. In addition, 746 patients were followed up and 38 patients were lost. In these patients, 700 (93.8%) cases met the stone removal criteria and 46 cases (6.2%) did not meet the stone removal criteria who need further treatment. The stone free rate (SFR) is 92.5%after 1-3 months and SFR of middle and upper calyceal calculi was higher than that of lower calyceal calculi significantly. The most common complications were fever (58/784, 7.4%), gross hematuria (540/784, 68.9%) and lpsilateral low back pain (47/784, 6.0%). The incidence rate of serious complication was 1.28%(10/784), including 5 cases of septic shock and 5 cases of subcapsular hematoma, which were cured after active treatment.

CONCLUSION

FURSL is a reliable treatment for small and medium calculi patients of upper urinary tract. The curative effect of stone removal is clear. The complications are few and the safety is high. However, there are certain limitations to the efficacy in treating larger stone and lower calyceal calculi.

Value of noncontrast computer tomography in predicting the characteristics of obstructive uropathy

OBJECTIVE

To explore the diagnostic value of noncontrast computed tomography (NCCT) in differentiating pyonephrosis from nonpyogenic hydronephrosis on the basis of CT values (in Horsfield unit [HU]).

METHODS

Data from patients diagnosed with obstructive uropathy at the First affiliated hospital of University of South China from November 2017 to January 2021 were subjected to retrospective analysis. In accordance with the gold standard-the presence of pus during the operation-all patients were divided into the nonpyogenic hydronephrosis group and the pyonephrosis group. The relationship between CT values and the presence or absence of pyonephrosis was performed using binary logistic regression. A receiver operating characteristic (ROC) curve was constructed to determine threshold values for classification on the basis of mean HU.

RESULTS

A total of 207 patients, including 100 males and 107 females, were enrolled. Out of the 207 cases, 124 cases of obstructive uropathy were nonpyogenic hydronephrosis and 83 cases were of pyonephrosis. The CT values of the pyonephrosis group were significantly higher than that of the nonpyogenic hydronephrosis group (t = 9.15, P < 0.05). The CT values were dependent on the presence or absence of pyonephrosis (P < 0.05). A HU threshold value of 9.75 could be applied to diagnose the presence of pyonephrosis.

CONCLUSION

The CT values of hydronephrosis might predict the presence of pyonephrosis in the kidney, and the CT value of 9.75 HU might be the appropriate threshold for its prediction.

Ex-vivo Renal Stone Dusting: Impact of Laser Modality, Ureteral Access Sheath, and Suction on Total Stone Clearance

INTRODUCTION AND OBJECTIVES

Conventional renal stone dusting is challenging; the holmium laser (Ho:YAG) and holmium with MOSES Effect (Ho:YAG-MOSES) fail to uniformly produce fragments <100 microns (i.e. dust). The superpulse thulium fiber laser (sTFL) may more effectively render uroliths into "dust," and may thus improve stone free rates. Accordingly, we performed ex-vivo evaluations with all three laser modalities, assessing stone fragments and stone clearance.

METHODS

Seventy-two ex-vivo porcine kidney-ureter models were divided into 12 groups of six: laser type (Ho:YAG, Ho:YAG-MOSES, sTFL), ureteroscope (URS) with and without applied suction, and presence or absence of a 14Fr ureteral access sheath (UAS). Calcium oxalate stones were pre-weighed and implanted into each kidney via a pyelotomy. Stones were treated at 16 watts using dusting settings of 0.4Jx40Hz (Ho:YAG) 0.2Jx80Hz (Ho:YAG-MOSES), and 0.2Jx80Hz (sTFL) for up to 20 minutes. No stone basketing was performed. Kidneys were bi-valved and residual fragments were collected, dried, weighed, and sieved to determine fragment size and stone clearance.

RESULTS

Initial stone mass (mg), procedure time (sec), and laser energy expenditure (kJ) were similar in all 12 groups. The greatest stone clearance was seen with sTFL+suction+UAS (94%) compared to a conventional technique (Ho:YAG+no suction+no UAS) (65%, p<0.01). The use of sTFL provided greater stone clearance than Ho:YAG or Ho:YAG-MOSES. Aspiration improved stone clearance for sTFL (p=0.01) but not for Ho:YAG or Ho:YAG-MOSES, consistent with the creation of smaller fragments with sTFL. Presence of a 14F UAS improved stone clearance in all scenarios (p<0.01).

CONCLUSIONS

In this ex-vivo study, stone clearance was optimized under the following conditions: sTFL laser, 14F ureteral access sheath, and aspiration. This combination resulted in 94% of stone fragments cleared; the 6% remaining fragments were all <2 mm. In all scenarios, deployment of a 14Fr UAS improved stone clearance.

Comparison of the Efficacy of ShuoTong Ureteroscopy and Simple Flexible Ureteroscopy in the Treatment of Unilateral Upper Ureteral Calculi

Background: ShuoTong ureteroscopy (Sotn-ureteroscopy, ST-URS), a new lithotripsy operation method developed on the basis of ureteroscopy, is widely used to treat ureteral stones in China. Its composition includes rigid ureteral access sheath, standard mirror, lithotripsy mirror, and ShuoTong perfusion aspirator (ST-APM). Here, we compared the efficacy and safety of the ST-URS and the flexible ureteroscope (F-URS) holmium laser lithotripsy in the treatment of unilateral upper ureteral calculi. Methods: Retrospective analysis was conducted on the clinical data of 280 patients who met the inclusion 1) urinary tract CT was diagnosed with unilateral single upper ureteral calculi above the L4 lumbar spine; 2) patient age was from 18 to 80 years old; 3) patients were informed and consented to this study; and 4) patients were approved by the hospital ethics committee (proof number: KY-2019-020) and the exclusion criteria for unilateral upper ureteral calculi in the First Affiliated Hospital of Xiamen University from January 2018 to November 2020, and they were divided into the ST-URS group and the flexible ureteroscopy (F-URS) group. Results: The stone-free rate of 1 day after operation of the ST-URS group was significantly higher than the F-URS group (63.71 vs. 34.62%, P < 0.0001). The operative time (38.45 vs. 46.18 min, P = 0.005) and hospitalization cost (27,203 vs. 33,220 Yuan, P < 0.0001) of the ST-URS group were significantly lower than the F-URS group. There were no significant differences in the success rate of ureteral access sheath placement, operative blood loss, stone-free rate of 1 month after operation, postoperative complications, postoperative hospital stay, and postoperative visual analog scale (VAS) pain score between the two groups (P > 0.05). In subgroups of a diameter of calculi ≥ 1.5 cm, calculi CT numerical value ≥ 1,000 Hounsfield unit and the preoperative hydronephrosis range ≥ 3.0 cm, ST-URS shows more advantages in the operative time, stone-free rate of 1 day after the operation, the hospitalization cost, and the incidence of postoperative complications. Conclusion: In unilateral upper ureteral stones treated with a holmium laser, compared with the simple F-URS, the ST-URS has a shorter operative time, lower hospitalization cost, and a higher stone-free rate of 1 day after the operation, suggesting that the ST-URS could be more widely applied in clinics.

Single-use flexible ureteroscopes: how to choose and what is around the corner?

PURPOSE OF REVIEW

The pace of technology development with single-use endoscopy has led to a range of disposable ureteroscopes. We review the development of single-use scopes, deconstruct the basic design and functional characteristics of available devices, and discuss future directions for next-generation platforms.

RECENT FINDINGS

Currently available devices are differentiated on the basis of several core features. The optical, deflection and irrigation characteristics are marginally different with no device clearly superior in every category. Studies comparing single-use ureteroscopes in patients linked to outcomes are limited. The incorporation of next-generation technologies into these platforms include sensors to monitor intrarenal pressure and temperature, suction of fluid and fragments, and computer vision for artificial intelligence.

SUMMARY

Each ureteroscope has specific features that may be advantageous in different circumstances. Single-use devices could transform the ureteroscope from a visual conduit to a transformative surgical instrument that improves outcomes and reduces complications.

Retrograde intrarenal surgery: Past, present, and future

With the recent technological advancements in endourology, retrograde intrarenal surgery has become a more popular procedure for treatment of urolithiasis. Furthermore, since the introduction of new laser systems and advanced flexible ureteroscopy with miniaturized ureteroscopes, the treatment indications for retrograde intrarenal surgery have expanded to include not only larger renal stones of >2 cm but also upper urinary tract urothelial carcinoma, ureteral stricture, and idiopathic renal hematuria. Clinicians must keep up with these trends and make good use of these technologies in the rapidly changing field of endourology. Simultaneously, we must consider the risk of various complications including thermal injury due to laser use, ureteral injury caused by the ureteral access sheath, and radiation exposure during retrograde intrarenal surgery with fluoroscopic guidance. This review focuses on the past, present, and future of retrograde intrarenal surgery and provides many topics and clinical options for urologists to consider.

Suction Use During Endourological Procedures

PURPOSE OF REVIEW

Equipment used in endourology is constantly evolving due to increasing incidence of urolithiasis. Suctioning has been used mainly in PCNL in conjunction with ultrasonic and ballistic devices for stone removal. Recently technological advances permitted the use of suctioning in more endourological techniques. This review aims to summarize the literature regarding these advancements and analyze the upcoming results.

RECENT FINDINGS

Several centers have conducted experimental and clinical studies on suctioning use during PCNL, mPCNL, and ureteroscopy and concluded that it is an effective and safe adjustment that improves stone-free rates and limits complication rates after these procedures. Suctioning use during common endourological procedures led to improved safety and efficacy among several indications. Due to the observational nature and small sample size of many studies, larger RCTs are needed to make safe conclusions.