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

Sand clearance vs. flowrate during ureteroscopy: studies in an in-vitro transparent kidney model

PURPOSE

Suction has recently been introduced into the ureteroscopic armamentarium to improve stone fragment and debris clearance. However, the benefits of suction appear to be limited by current irrigation systems. This study aimed to measure the time to clear sand ureteroscopically from a transparent silicone kidney-ureter model at different flowrates and compare with results with conventional pressurized irrigation and intermittent suction.

METHODS

A LithoVue™ Elite ureteroscope was inserted through a Clear Petra 11/13 Fr 46 cm or 12/14 Fr 50 cm FANS device into a transparent silicone kidney model. Irrigation was delivered from a peristaltic pump at rates of 18-90 ml/min with pump assisted outflow or from a pressurized source with suction assisted outflow. Intrarenal pressure (IRP) was maintained between 30-40 cmH2O. Trials were conducted to measure the time required to completely aspirate 0.5 g of sand from the mid and upper calyces.

RESULTS

Sand was cleared more quickly from the kidney model as flowrate increased up to ~ 70-80 ml/min. Use of continuous flowrate was more efficient at clearing sand than variable flowrate produced by bursts of intermittent suction.

CONCLUSIONS

Flowrate is a primary variable affecting efficiency of sand clearance in in vitro studies. Current clinical methods that utilize intermittent suction during ureteroscopy are likely less efficient than configurations that provide continuous flowrates. Incorporation of IRP feedback into irrigation systems may facilitate high flowrate while maintaining stable low IRP, thereby enhancing efficiency and safety of ureteroscopy.

The role of suction devices in enhancing outcomes of retrograde intrarenal surgery: a narrative review by the YAU urolithiasis and section of EAU endourology

PURPOSE OF REVIEW

To provide a comprehensive overview of existing literature on suction-assisted ureteroscopy, evaluating its effectiveness and associated complications.

RECENT FINDINGS

A literature review was conducted in December 2024 using the MEDLINE, EMBASE and Scopus databases by two independent authors. To structure and address the clinical question, "Do suction devices improve outcomes in RIRS?", we employed the PICOS (Patient, Intervention, Comparison, Outcome, Study Type) model. Exclusion criteria included case reports, studies involving suction techniques outside the context of endocorporeal laser lithotripsy (ELL), non-English language articles and articles or clinical trials with fewer than 15 patients.

SUMMARY

Among the 36 included studies, 28 studies focused on SUAS, of which seven specifically investigated SUAS with pressure measurement, three studies examined DISS, three studies evaluated SURE and two comparative studies analyzed different suction techniques. The presented results show that advancements in suction technology seem very promising and likely to shift endourological practice.

Assessment of a novel bendable-tip ureteral access sheath with integrated suction: an in vitro study

Surgical management of urinary stones has significantly evolved with the advent of extracorporeal shockwave lithotripsy, flexible ureterorenoscopy (fURS), and percutaneous nephrolithotomy. For lower pole stones larger than 1 cm, the choice between fURS and miniaturized percutaneous nephrolithotomy remains debated. fURS with ureteric access sheaths (UAS) is a widely utilized technique, but fragment clearance is challenging in unfavorable anatomical conditions and/or lower pole stones. This study compares a novel flexible suction UAS (FANS) with a standard UAS in an in vitro model of lower pole stones. An in vitro experiment was conducted using an anatomical model of the urinary tract with artificial stones simulating complex 1-cm lower pole stones. Fourteen procedures were performed using either a 12/14 Fr diameter standard UAS or FANS. Every experiment was performed by a single surgeon using a 8.4 Fr single-use digital flexible ureteroscope and holmium:YAG laser set at 0.5 J, 25 Hz, and short pulse with a 272 μm fiber. Operative times, stone clearance rates, lasering times, were recorded and the residual stone masses (> 2 mm) was quantified. Complete stone clearance was achieved in 5 out of 7 procedures using FANS while no complete stone clearance was achieved using the standard UAS. The median laser time [27:33 (26:06-28:24) vs 24:02 (21:25-25:04) mm:ss, p = 0.017] and total energy output energy [20663 (19,575-21,325) vs 18,270 (16,069-18,931) J, p = 0.017] were significantly lower in the FANS group (p = 0.017), and the operative time was comparable. This in vitro experiment suggests that fURS with novel FANS may improve stone clearance and improve laser efficiency when compared to the standard UAS, without increasing operative times. Further clinical trials are warranted to confirm these findings.

A Novel ±20° Gravity-Assisted Position for Tip-Bendable Suction Ureteral Access Sheath in Retrograde Intrarenal Surgery: A Multicenter Retrospective Study on Large Stone Management

Purpose: To evaluate the efficacy of combining a tip-bendable suction ureteral access sheath (S-UAS) with gravity-assisted positioning to improve stone-free rates (SFRs) in retrograde intrarenal surgery (RIRS) for upper urinary tract stones (UUTS). Methods: A multicenter retrospective cohort study was conducted across three urological centers from July 2023 to August 2024. A total of 369 patients with UUTS treated with RIRS using S-UAS were included. Patients were categorized into two groups based on surgical positioning: the ±20° gravity-assisted position group and the standard lithotomy group. SFRs were classified into three grades: Grade A (no residual fragments on CT), Grade B (≤2mm fragments), and Grade C (≤4mm fragments). Key outcomes measured included immediate and 3-month SFR, operative time, and complication rates. Logistic regression analysis was used to identify factors associated with improved SFR. Results: The ±20° gravity-assisted position group showed a significantly higher immediate Grade-A (71.3% vs 48.1%, p < 0.001) and Grade-B SFR (86.0% vs 67.2%, p < 0.001) compared to the standard lithotomy group. This superiority in Grade-A SFR persisted at 3 months (76.0% vs 49.6%, p < 0.001). The median operative time was shorter in the ±20° gravity-assisted position group (67 vs 71 minutes, p = 0.0032) and the frequency of stone basket use was lower in ±20° gravity-assisted position. Multivariate analysis revealed that the lithotomy position was independently associated with a lower stone-free probability (adjusted odds ratio 0.36, 95% confidence interval 0.17-0.80; p = 0.012). No significant differences were observed in complication rates between the two groups. Conclusion: The ±20° gravity-assisted position improves immediate SFR in RIRS for UUTS, with shorter operative times. Combining gravity-assisted positioning with S-UAS is an effective strategy to optimize surgical outcomes in RIRS.

Comparison of safety and efficacy of negative pressure aspiration assisted retrograde intrarenal surgery and traditional percutaneous nephrolithotomy in the treatment of upper urinary tract stones larger than 2 cm: a systematic review and meta-analysis

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is widely regarded as the first-line treatment for upper urinary tract stones larger than 2 cm, as recommended by major urological associations. However, a growing body of research highlights the safety and effectiveness of retrograde intrarenal surgery (RIRS) for managing stones of this size in the upper urinary tract, especially with the advent of suction-assisted techniques in RIRS. This study aims to systematically evaluate the safety and efficacy of negative pressure aspiration-assisted RIRS (NPAA-RIRS) in comparison to traditional PCNL.

METHOD

Eligible studies were found by searching the PubMed, Embase, Web of Science and the CNKI databases for relevant reports published until July 2024. Outcome measures included initial and final stone-free rate (SFR), secondary operation, operation time, hemoglobin level reduction, blood transfusion, interventional embolization, postoperative hospital stay, complications. The assessment of publication bias was conducted using a funnel plot. Ten studies from nine articles were included, involving 1259 patients.

RESULTS

NPAA-RIRS group showed lower hemoglobin level reduction (WMD = -1.31, 95% CI [-1.64, -0.99], P < 0.001), less blood transfusion (RR = 0.15, 95% CI [0.05, 0.50], P = 0.002), shorter postoperative hospital stay (WMD: -1.93, 95% CI [-2.54, -1.32], P < 0.001), lower Clavien-Dindo I-II complication rate (RR: 0.51, 95% CI [0.38, 0.67], P < 0.001), and lower overall complication rate (RR = 0.52, 95% CI [0.40, 0.68], P < 0.001) compared to the PCNL group. The PCNL group had shorter operation time (WMD = 0.68, 95% CI [0.22, 1.13], P = 0.003), higher initial SFR (RR = 0.87, 95% CI [0.83, 0.92], P < 0.001), and lower rate of secondary operation (RR = 2.51, 95% CI [1.52, 4.12], P < 0.001) compared to the NPAA-RIRS group. There were no statistically significant differences between the two groups in interventional embolization (RR = 0.28, 95% CI [0.06, 1.33], P = 0.11), final SFR (RR = 0.98, 95% CI [0.94, 1.01], P = 0.740), and Clavien-Dindo III-IV complication rate (RR: 0.65, 95% CI [0.28, 1.51], P = 0.316).

CONCLUSION

For upper urinary tract stones larger than 2 cm, both NPAA-RIRS and PCNL are equally safe and effective, achieving comparable final SFR. NPAA-RIRS offers advantages in terms of reduced complications, whereas PCNL shows benefits in shorter operation times and a lower likelihood of requiring secondary procedures. Clinicians can therefore select the most suitable approach based on individual patient circumstances.

Enhanced stone-free rates with suctioning ureteral access sheath vs. traditional sheath in retrograde intrarenal surgery: a systematic review and meta-analysis

BACKGROUND

As a safe approach to the upper urinary tract, flexible ureteroscopic lithotripsy (fURL) is a widely accepted treatment for nephrolithiasis. Sometimes, this technique can rely on the natural expulsion of stones, increasing the risk of infections and stone recurrence. To mitigate these issues, some studies tried to use a suctioning ureteral access sheath (S-UAS).

METHODS

A systematic review was conducted across multiple databases for trials comparing S-UAS with traditional (T-UAS) in retrograde intrarenal surgery (RIRS). The primary endpoint was the stone-free rate (SFR), while adverse effects, operative time, fever rate, and hospital stay were analyzed as secondary outcomes.

RESULTS

We retrieved 8 articles, encompassing a total of 2,255 patients, with 978 in the S-UAS group and 1,247 in the T-UAS group. Our analysis revealed a higher SFR in the S-UAS group after 1 day, and also at later time points (one or three months) (OR 3.79; 95% CI 1.70-8.46; p = 0.001; I2 = 89.2%) and (OR 1.98; 95% CI 1.52-2.59; p < 0.001; I2 = 0%), respectively. Regarding surgical complications, we observed a lower incidence in the S-UAS group (OR 0.37; 95% CI 0.26-0.51; p < 0.001; I2 = 0%), as well as a reduced fever rate (OR 0.34; 95% CI 0.24-0.48; p < 0.001; I2 = 0%) and a shorter length of hospital stay (MD -0.11; 95% CI -0.16 to -0.05; p < 0.001; I2 = 39.6%). No differences were found in the operative time between both approaches (MD -2.49; 95% CI -7.62-2.65; p < 0.343; I2 = 88.3%).

CONCLUSION

Our study suggests that using S-UAS in RIRS may enhance the SFR, and also reduce both complications and hospital stay.

TRIAL REGISTRATION

This systematic-review and meta-analysis was prospectively registered on PROSPERO under protocol CRD42024543084.

Development of machine learning models to predict the risk of fungal infection following flexible ureteroscopy lithotripsy

BACKGROUND

The flexible ureteroscopy lithotripsy (F-URL) is an important treatment for upper urinary tract stones. However, urolithiasis, surgical procedures, and catheter placement are risk factors for fungal infections. Our study aimed to construct a machine learning algorithm predictive model to predict the risk of fungal infection following F-URL.

METHODS

This study retrospectively collected the clinical data of patients who underwent F-URL at the Second Affiliated Hospital of Zhengzhou University from January 2016 to March 2024. The patients were divided into a non-fungal infection group and a fungal infection group based on whether a fungal infection occurred within three months post-surgery. The patient data from January 2016 to December 2023 were used as training data, and the patient data from January 2024 to March 2024 were used as testing set. The training data was randomly divided into a training set and validation set at a ratio of 90:10. Use LASSO regression to screen clinical features based on the training set. Nine machine learning algorithms, Logistic Regression (LR), k-Nearest Neighbours (KNN), Support Vector Machines (SVM), Random Forest (RF), Categorical Boosting (CatBoost), eXtreme Gradient Boosting (XGBoost), Adaptive Boosting (AdaBoost), Gradient Boosting Machines (GBM), and Neural Network (NNet), were used to construct models. The performance of these nine models was evaluated and the best predictive model was selected based on the validation set, and evaluate the best predictive model's generalization ability using the testing set. Visualize the constructed optimal machine learning model using the SHapley additive interpretation (SHAP) value method. SHAP force plots were established to show the application of the prediction model at the individual level.

RESULTS

A total of 13 clinical features were used to construct predictive models: age, diabetes mellitus (DM), history of malignancy, being bedridden, admission white blood cells (WBC), preoperative ureteral stenting, operation time, postoperative fever, postoperative Neu, carbapenem antibiotics use, duration of antibiotic therapy, length of hospital stay (LOS), and postoperative stent duration. Comparing the performance of 9 prediction models, we found that the model constructed using XGBoost algorithm had the best performance. The model constructed using XGBoost algorithm shows good discrimination, generalization and clinical applicability in the testing set.

CONCLUSIONS

The XGBoost model developed in this study has good predictive ability and clinical applicability for evaluating the risk of fungal infection following F-URL.

Development of an Alginate Gel Composite with Antibacterial Properties Capable of Binding Calcium-Based Residual Stone Fragments in Endoscopic Stone Surgery

Background: Complete removal of urinary stones remains a challenge, as residual fragments can contribute to recurrence and postoperative urinary tract infections. This study presents an initial laboratory investigation into the development of an alginate gel composite designed to bind calcium-based stone remnants and exhibit antibacterial properties. Methods: To evaluate gel formation, calcium oxalate powder reagent and sodium alginate (SA) powder reagent were mixed in a Becker glass and stirred on a hot plate. Stones from 17 patients who underwent stone surgery were crushed, and gel formation was confirmed using the same experimental conditions with SA powder reagent. A gel composite material containing silver nitrate and vancomycin was prepared, and antibacterial activity against Staphylococcus aureus and Escherichia coli was tested over a 5-minute period. A mixture of 0.5 g alginic acid and 0.05 g calcium oxalate monohydrate powder reagent with 50 mL distilled water formed a gel after 30 minutes. Results: Sandy stones composed of calcium oxalate formed a better gel composite when mixed with SA than those composed of uric acid. In the antibacterial test of the alginate gel composite containing silver nitrate and vancomycin against S. aureus and E. coli, the number of live bacteria in the control and alginate gel composite was 3.5 × 103 and <10, respectively. Conclusion: This study represents a preliminary laboratory investigation into the development of an alginate gel composite for potential use in urinary stone management. Further preclinical studies are necessary to evaluate its efficacy and safety before clinical translation.

Comparison of suction technique and non-suction technique in retrograde intrarenal stone surgery: a systematic review and meta-analysis

OBJECTIVE

To evaluate the clinical efficacy of retrograde intrarenal stone surgery (RIRS) using the vacuum suction technique for the treatment of upper urinary calculi.

METHODS

A comprehensive literature search was conducted across multiple databases, including PubMed, Embase, Sino Med, CNKI, WANFANG DATA, and Cochrane. We included studies comparing vacuum suction RIRS with non-vacuum RIRS. Following the PRISMA guidelines, we performed a meta-analysis of the selected studies. Inclusion criteria were randomized controlled trials (RCTs), case-control studies, and retrospective studies evaluating the efficacy of these techniques. Key outcomes analyzed included operative time, hospitalization duration, stone-free rates, and complication rates. Statistical analyses were conducted using mean differences (MD) for continuous variables and odds ratios (OR) for dichotomous outcomes, with corresponding 95% confidence intervals (CI).

RESULTS

Sixteen studies (6 RCTs, 1 case-control study, and 9 retrospective studies) involving a total of 2029 patients were included. Meta-analysis revealed that the vacuum suction technique significantly reduced operative time (MD = - 14.45 min, 95% CI [- 18.45; - 10.44], P < 0.00001) and hospital stay (MD = - 0.54 days, 95% CI [- 0.80; - 0.28], P < 0.00001). In addition, patients in the vacuum suction group had a higher stone-free rate (OR = 3.57, 95% CI [2.57; 4.95], P < 0.00001) and lower complication rates, particularly in reducing postoperative fever.

CONCLUSION

The application of the vacuum suction technique in RIRS significantly improves clinical outcomes by reducing operative time and hospitalization duration, enhancing stone-free rates, and lowering postoperative complication rates. This technique demonstrates a clear clinical advantage over non-vacuum RIRS and should be considered a preferred option for the management of upper urinary tract stones.

Direct-in-scope suction with a 5.1Fr large working channel ureteroscope: what stone dust size for effective evacuation during laser lithotripsy? An in vitro analysis by PEARLS and section of EAU Endourology

PURPOSE

A novel larger 5.1Fr working channel flexible ureteroscope for Direct-In-Scope Suction (DISS) has recently been introduced. However, the optimal stone dust size for successful evacuation without working channel blockage is currently unknown.

METHODS

In vitro assessment of the PU400A 9.2Fr ureteroscope (Zhuhai Pusen Medical Technology Co., Ltd, China) was performed with BegoStone particle sizes ≤ 2000 μm (size range 1000-2000 μm), ≤ 1000 μm (500-1000 μm), ≤ 500 μm (250-500 μm), ≤ 250 μm (125-250 μm) and ≤ 125 μm (63-125 μm), in a kidney calyx model. This was conducted with an empty working channel, and with occupancy by 150 μm Olympus, 200 μm Quanta, 270 μm Dornier laser fibers. Primary outcome was complete suction-evacuation without working channel blockage. Secondary outcome was evacuation speed for particle sizes that did not have blockage.

RESULTS

A stone particle size upper limit of 250 μm was found to achieve complete suction-evacuation without blockage, across all working channel occupancy situations. For stone particle size of range 125-250 μm, evacuation speeds were 35, 26, 13, 11 mm3/s across empty, 150 μm Olympus, 200 μm Quanta, 270 μm Dornier laser fiber occupancy, respectively (ANOVA = p < 0.001). For stone particle size range 63-125 μm, evacuation speeds were 19, 14, 9, 8 mm3/s respectively (ANOVA = p < 0.001).

CONCLUSION

The 5.1Fr working channel DISS ureteroscope allows a stone particle size limit of 250 μm to be suction-evacuated without blockage, even with laser fiber occupancy. With a laser fiber, a smaller 150 μm fiber size allows better particle evacuation speeds. Urologists should therefore aim for a dust particle size of ≤ 250 μm in routine DISS with the 5.1Fr working channel ureteroscope, for effective intraoperative stone evacuation.

Is flexible navigable suction ureteral access sheath (FANS) safer and more efficient than conventional sheaths? Italian multicentric experience

BACKGROUND AND OBJECTIVE

The flexible and navigable suction ureteral access sheath (FANS) with continuous flow lithotripsy may improve stone-free rates (SFR) in ureterorenolithotripsy procedures, reducing operative time and the need for fragment extraction. This study aimed to compare the safety and efficacy of FANS versus conventional sheaths in patients undergoing retrograde intrarenal surgery (RIRS) for renal stones.

METHODS

From January to September 2024, patients undergoing RIRS with high-power pulsed lasers (60 W Ho:YAG or 100 W pTm:YAG) were randomized to receive either a conventional sheath (Group 1) or FANS (Group 2). Data on baseline characteristics, operative details, and complications were collected. SFR, defined as the absence of fragments > 3 mm, was assessed with non-contrast CT scans one-month post-surgery. Statistical significance was set at p < 0.05.

RESULTS

A total of 132 patients were enrolled (70 with conventional sheath, 62 with FANS). The FANS group had shorter operative times (55.25 vs. 61.36 min, p = 0.028), while laser time was similar between groups. Postoperative complications were lower in the FANS group. At one month, the FANS group had a higher SFR (95% vs. 67%, p < 0.005) and fewer re-interventions (p = 0.02).

CONCLUSIONS

FANS significantly improves SFR without increasing postoperative complications postoperative complications or negatively affecting recovery, offering a promising alternative to conventional sheaths in ureterorenolithotripsy procedures. FANS improves kidney stone surgery outcomes, providing better stone removal, fewer complications, and faster recovery compared to the standard tool.

Flexible ureteroscopy combined with potassium sodium hydrogen citrate(PSHC) intervention improves the stone-free rate(SFR) for 20-30 mm uric acid renal stones

OBJECTIVE

To evaluate the efficacy and safety of combining flexible ureteroscopy (FURS) with potassium sodium hydrogen citrate(PSHC) for the treatment of 20-30 mm uric acid renal stones.

METHODS

A retrospective analysis of outcomes of patients with 20-30 mm uric acid renal stones who were treated with FURS and holmium lithotripsy was conducted between July 2021 and May 2024. Of them, 60 patients accepted FURS combined potassium sodium hydrogen citrate(PSHC) therapy while 70 patients underwent the FURS procedure alone. The demographic data, stone characteristics, surgical details, and perioperative outcomes of the patients were assessed retrospectively. Stone-free status was defined as the complete absence of stones on computed tomography.

RESULTS

Totally 130 patients were enrolled and analyzed in this study. No significant differences were found between the two groups in terms of gender, age, body mass index, comorbidities, stone burden, stone density, number of stones, or laterality. The mean operation time, American Society of Anesthesiologists (ASA) score, postoperative stay, and complication rate were also similar between the groups. The combined group incurred higher costs (p < 0.01),but it achieved significantly higher stone-free rate and Wisconsin Stone Quality of Life Questionnaire score at 4 weeks post-operatively (96.7% vs. 85.7%,p = 0.029;124.63 vs. 114.44,p < 0.01). Additionally, the combined group had a significantly higher urine pH at 4 weeks postoperatively compared to the non-combined group (6.63 vs. 5.50, p < 0.01).

CONCLUSION

Compared to a single procedure, FURS combined with PSHC therapy is an effective and safe treatment for 20-30 mm uric acid renal stones.

A Feasibility Study on the Efficacy and Safety of a Novel Tip-Flexible Suction Ureteral Access Sheath Combined with Flexible Ureteroscopic Lithotripsy for Treating Kidney Stones ≥30 mm

Objective: To evaluate the efficacy and safety of a novel tip-flexible suction ureteral access sheath (NTFS-UAS) combined with flexible ureteroscopic lithotripsy (FURS) for treating kidney stones ≥30 mm in a large cohort. Methods: The clinical data of 206 patients with renal calculi ≥30 mm treated by NTFS-UAS combined with FURS from June 2021 to September 2023 were analyzed retrospectively. The outcomes under investigation encompassed demographic information, stone-related characteristics, operative time, stone-free rates (SFRs), and postoperative complications. Results: The median operation duration was 110 minutes (interquartile 84.00-146.25 minutes). Immediate and 1-month SFRs were 83.98% and 85.44%, respectively. Multivariate analysis revealed five risk factors independently affecting stone clearance rate: stone size (≥50 mm, odds ratio [OR] = 3.826, p = 0.039), stone number (multiple: OR = 8.745, p = 0.015), stone location (multiple calyces: OR = 10.371, p = 0.045; lower calyx: OR = 9.615, p = 0.047), severe hydronephrosis (OR = 8.338, p = 0.002), and the Resorlu-Unsal scoring system (RUSS) score (6-7: OR = 10.829, p = 0.009; 4-5: OR = 4.223, p = 0.008). The incidence of Clavien-Dindo grade II-III complication was 5.82%. Positive preoperative urine culture (OR = 9.533, p = 0.012) and RUSS score (6-7: OR = 25.678, p = 0.026; 4-5: OR = 11.444, p = 0.038) were identified as the most important variables that may contribute to the development of high-grade postoperative complications. Conclusion: NFTS-UAS combined with FURS achieved satisfactory outcomes with good efficacy and safety for treating large renal stones ≥30 mm, and it can be utilized as an effective treatment option for patients having contraindications or preference against percutaneous nephrolithotomy. In addition, clinical factors, such as stone size, severe hydronephrosis, positive preoperative urine culture, and RUSS stone score that likely affected the outcomes of NFTS-UAS, should be fully taken into account when the surgeon performing FURS using NFTS-UAS.

Real time monitoring of intrarenal pressures while using the flexible and navigable suction ureteral access sheath

PURPOSE

To report on in-vivo intrarenal pressure (IRP) during flexible ureteroscopy for treatment of kidney stones while using the novel flexible and navigable suction ureteral access sheath (FANS).

METHODS

A retrospective observational analysis was performed for 25 patients undergoing routine flexible ureteroscopy for treatment of renal stones between February 2024 and June 2024 from two centres in Canada. The LithoVue Elite™ ureteroscope (Boston Scientific Corp., Marlborough, MA, USA) with pressure sensing capability was used together with the Clearpetra® Ureteral Access Sheath System (Well Lead Medical Co. Ltd., Guangzhou, China) for all cases. Irrigation was via a pressure bag set at 250mmHg where possible and the access sheath was connected to wall suction at 200mmHg. Median and maximum IRP, as well as the distribution of cumulative procedure times according to various IRP ranges were analyzed.

RESULTS

The median age of the patients was 56 years, with a median BMI of 26.7 kg/m2. The median (Interquartile range {IQR}) IRP for all the cases was 22.0 (15.0-36.5) mmHg, with a median (IQR) procedure time of 35.9 (16.4-54.8) minutes. The IRP remained below 40mmHg in 76.2% of the total time in all procedures, and was below 60mmHg in 94.1% of the time. Significant variables associated with lower IRP were having a prior endourological procedure, pre-stenting, larger ureteral access sheath size and use of pre-operative alpha blocker. Age, BMI and total stone volume did not significantly affect IRP.

CONCLUSIONS

Low intrarenal pressures can be achieved with the use of FANS, even with higher irrigation pressures. Alpha blocker use, larger sheath size, prior endourological procedures and pre-stenting are all associated with lower IRP.

Harnessing magnetism: evaluation of safety, tolerance and feasibility of magnetic kidney stone retrieval in vivo in porcine models

The primary objective of urolithiasis therapy is complete stone removal and highest stone-clearance rates possible to minimize recurrence. A novel approach that employs a magnetic suspension and a magnetic probe for the passive collection and removal of small residual fragments was developed. This study assessed the feasibility of this system in porcine models. Five female domestic pigs underwent retrograde intrarenal surgery under general anaesthesia to assess the new magnetic system. Pre-analysed human calculi were endoscopically inserted and comminuted using lithotripsy. The magnetic suspension was applied, and the magnetic-stone fragment complex was extracted. After nephrectomy, independent blinded pathologists evaluated all the kidneys. Safety and tolerance assessments revealed no adverse events (i.e. no complications on the Clavien-Dindo scale > 1) or complications associated with treatment. This study revealed superficial urothelial damage in all animals, characterized by desquamation and inflammation, caused primarily by the insertion of access sheaths and laser lithotripsy. Residual magnetic particles were observed in the renal pelvis but did not show signs of toxicity even though this study is limited to the acute treatment. No pathological indicators were observed in the hemogram and urinalysis. Overall, the treatment did not cause any significant pathological changes. Preclinical in vivo evaluation of magnetic extraction of small rest fragments in porcine kidneys presents a promising, atraumatic approach for fragments removal. It demonstrated safety, tolerance, and feasibility that warrants clinical investigation. This method has the potential to increase stone-clearance rates with shorter extraction times, offering a possibility for addressing the challenge of urolithiasis in clinical practice.

Assessing flexible ureteroscopy outcomes for lower Pole versus non lower Pole stones using the flexible and navigable suction ureteric access sheath: a prospective multicenter study by EAU Endourology and PEARLS group

PURPOSE

Use of suction in flexible ureteroscopy is increasing lately. The introduction of flexible and navigable suction access sheath (FANS) has shown improved stone free rate (SFR). However, its efficacy in lower pole stone (LPS) in terms of SFR and complications is yet to be studied.

METHODS

We collected data from 25 centers that included 394 adult patients undergoing ureteroscopy using FANS. Non contrast CT (NCCT) scan was done within first 30 days post operatively to access the SFR. Residual fragments were graded as A: 100% SFR; B: single fragment ≤ 2 mm; C: single fragment 2.1-4 mm; D: Single or multiple fragments > 4 mm. Post operative complications were recorded.

RESULTS

Out of 394 patients, non LPS (group1) comprised of 268 patients, rest 126 patients had LPS (group 2). Single stage zero fragment SFR was seen in 58.6% (group 1) vs. 54.8% (group 2) (P = 0.619). Single stage grade A + B SFR was achieved in 96.6% vs. 98.4% in groups 1 and 2 respectively. On multivariate analysis Thulium fiber laser use was significantly associated with higher odds of being grade A stone-free, while stone volume with lower odds. In LPS group only two patients needed reintervention. The highest grade of complication was Clavien 2, which was seen in 3.2% LPS group.

CONCLUSION

Use of flexible and navigable suction ureteric access sheath for lower pole stones is effective and safe. The stone free rate of lower pole stones is comparable to non-lower pole locations with very low reintervention rate in both groups.

Comparison of tip-bendable aspiration-assisted and standard access sheaths in the treatment of lower calyceal stones

OBJECTIVE

The aim of this study was to compare the success and complication rates of retrograde intrarenal surgery for lower calyceal renal stones performed with novel tip-bendable suction ureteral access sheaths and standard ureteral access sheaths.

METHODS

Between March 2023 and March 2024, a total of 88 patients underwent retrograde intrarenal surgery for lower renal calyceal stones smaller than 20 mm. Based on the access sheath used, patients were divided into two groups: Group 1 (n=43) included patients treated with novel tip-bendable suction ureteral access sheaths and Group 2 (n=45) included patients treated with standard ureteral access sheaths. The pre- and postoperative data of the two groups were compared. Complications were assessed by using the Modified Clavine Dindo system, and stone-free rate was assessed after 4 weeks by using non-contrast computed tomography.

RESULTS

There was no significant difference between the groups regarding demographic data or preoperative laboratory results, and the median stone size was comparable in both groups. The stone-free rate did not show any significant difference between the two groups. However, the median residual stone size was substantially higher in the standard ureteral access sheaths group [4.25- (3.75-5) vs. 6- (5-7), p=0.01] and the surgical duration was less in the novel tip-bendable suction ureteral access sheaths group (p=0.032).

CONCLUSION

Our current findings demonstrate that the use of a new tip-bendable suction-assisted access sheath during retrograde intrarenal surgery in the management of lower calyceal stones less than 2 cm may shorten the operative duration, limit the rate of complications, and end up with smaller residual stone fragments when compared with the use of standard ureteral access sheath.

Novel small fragment removal system may improve extraction of renal calculi: an in vitro study

OBJECTIVE

To describe a novel Small Fragment Removal System (SFRS) which is hypothesized to improve stone fragment removal during flexible ureteroscopy in patients with urolithiasis. The SFRS consists of three parts: a Syphon Ureteric Access Sheath (SUAS), a Dual Action Pump (DAP) and an Agitator. This bench assessment aims to assess the SFRS's impact on intra-renal pressure (IRP), irrigant flow rate and stone fragment removal compared to a traditional UAS.

MATERIALS AND METHODS

A validated phantom kidney and fibre optic pressure sensor was used to assess IRP. Standardized irrigation via a flexible ureterorenoscope was instilled through a traditional UAS and compared to the novel SFRS. Both were 11/13Fr in size. Measured minute volume, IRP and percentage of stone fragments removed were compared.

RESULTS

The mean IRP using a traditional UAS and SFRS was 24,3mmHg and 9,4mmHg respectively. The flow rate of the traditional UAS was 25mL/min, compared to 31mL/min with the SFRS attached. During bolus fluid administration using the traditional UAS the maximum IRP increased to 41mmHg, compared to 9,3mmHg with the SFRS attached. A mean of 42,7% (0,103 g of 0,305 g) of weighed dry stones were removed with the traditional UAS compared to 77,6% (0,233 g of 0,299 g) with the SFRS attached, p = 0,017.

CONCLUSIONS

The described Small Fragment Removal System (SFRS) is different from traditional UASs by incorporating a syphoning mechanism. In addition, it has a Dual Action Pump which both boluses and augments the aspiration of irrigant by the Syphon. It further includes a deflectable Agitator to flush out stone fragments.

Complications of Single-Use Flexible Ureteroscopy vs. Reusable Flexible Ureteroscopy: A Narrative Review

Urolithiasis, or kidney stones, is a painful condition that is becoming increasingly common worldwide. For many, the solution lies in a minimally invasive procedure called flexible ureteroscopy (fURS). This technique involves inserting a tiny, flexible scope into the urinary tract to break up and remove stones. Reusable fURS scopes have traditionally been the norm. However, concerns about infection control and instrument durability have led to the development of single-use scopes. While both methods offer effective treatment, the question remains: which one is safer and more efficient? To answer this, we conducted a comprehensive review of the available research. We analyzed 37 studies that compared single-use and reusable fURS complication rates. While both methods carry risks, such as bleeding, infection, and ureteral injury, the overall complication rates were found to be similar. As technology continues to advance, fURS is becoming even safer and more effective. However, there is still a need for standardized reporting and further research to better understand the potential risks and benefits of both single-use and reusable scopes. Ultimately, the choice between the two will depend on various factors, including patient factors, surgeon preference, and healthcare resource availability.

For upper ureteral stone, semirigid ureteroscopy or flexible ureteroscopy? Strengths and weaknesses

BACKGROUND

Flexible and semirigid ureteroscopy are two often used modalities in treating for upper ureteral stone. How about the outcome of each procedure?

METHODS

A retrospective cohort study among 167 patients who underwent flexible or semirigid ureteroscopic lithotripsy was performed. The pre-, intra-, postoperative and one-year follow-up outcomes were taken into comparison.

RESULTS

Significantly higher instant stone-clearance rate (81.3% vs. 92.4%, p = .032) and less operative time (62.1 ± 27.6 min vs. 44.1 ± 24.6 min, p<.001) were found in semirigid ureteroscopy. However, the stone-clearance rate at one month (90.7% vs. 93.5%, p = .500) was similar. Baseline characteristics including patient demographics, stone characteristics, duration of stone symptoms, hospital stay, expense, and complications between groups were approximately same. Three cases of stricture were found in the flexible ureteroscopy, and two in the semirigid ureteroscopy. Outcomes showed no significant difference. Further analysis showed that flexible ureteroscopy was likely more negatively affected by hydronephrosis and stone size, and semirigid ureteroscopy was more affected by stone location.

CONCLUSION

flexible ureteroscopy and semirigid ureteroscopy both had high stone clearance rate in the treatment for upper ureteral stones. They had similar outcomes and follow-up results. However, they also had their each most suitable application object.

Pressure reduction and suction characteristics of the new digital single use flexible ureteroscope with suction: an in-vitro experimental study

PURPOSE

To assess the time taken by the single use 7.5Fr suction flexible ureteroscope to reduce pressure under 40 mm Hg and to characterize the behavior of stones, fragments and dust during suction activation.

METHODS

An in vitro setting was developed for this experiment. A saline-filled globe, with the 7.5Fr single-use suction flexible ureteroscope, PU3033AH (ZhuHai Pusen Medical Technology Co, Ltd, Guangdon, China), an automatic irrigation pump and a pressure monitoring set were used at four modalities; i) continuous suction, no irrigation inflow; ii) continuous suction, irrigation inflow on; iii) one-second rate intermittent suction, irrigation inflow on, and iv) half-second rate intermittent suction, irrigation inflow on. The behavior of calcium oxalate stones from 0.5 to 5 mm when being aspirated via the ureteroscope into a plastic container filled with saline was recorded.

RESULTS

Suction with the PU3033AH worked properly with the inflow irritation on. The fastest strategy to lower the pressure was by continuously pressing the suction button with the irrigation inflow on. Overall, the median time to reach 40 mg was roughly 3.5 s. The PU3033AH could aspirate 0.5 mm stones. The suction mode on a continuous pattern allowed the relocation of stones ranging from 1 to 5 mm on an experimental setup with no obstacles.

CONCLUSION

The PU3033AH was efficient in lowering pressure in a closed cavity mimicking the renal pelvis. Likewise, stone fragments under one millimeter were aspirated by the device whereas stones from one to five mm could be displaced when activating suction in continuous mode on an experimental setup with no obstacles.

Efficacy analysis of tip-flexible suction access sheath during flexible ureteroscopic lithotripsy for unilateral upper urinary tract calculi

PURPOSE

This study aims to evaluate the efficacy of tip-flexible suctioning ureteral access sheath (TFS-UAS) compared to traditional ureteral access sheath (T-UAS) in flexible ureteroscopic lithotripsy (FURL) for unilateral upper urinary tract calculi.

METHODS

The study retrospectively compared outcomes from 103 cases using TFS-UAS and 138 using T-UAS treated with FURL for unilateral upper urinary tract calculi from January to October 2023. Assessed parameters included patient demographics, stone characteristics, preoperative urine cultures, ureteral pre-stenting, comorbidities, procedure time, stone-free rate (SFR), utilization of stone retrieval baskets, and postoperative Systemic Inflammatory Response Syndrome (SIRS) rates. The maximum angle of deflection was also measured when the flexible ureteroscope was located in different parts of the TFS-UAS with different diameters in vitro.

RESULTS

The TFS-UAS group achieved a higher Immediate SFR (76.70% vs. 63.77%, p = 0.031) and final SFR (89.32% vs. 73.91%, p = 0.003) than the T-UAS group, especially in the lower calyx stones (80.00% vs. 41.18%, p = 0.018) and upper urinary tract calculi with a cumulative diameter of 2 cm or larger (68.97% vs. 42.11%, p = 0.029). Notably, TFS-UAS with a 10 French (F) inside diameter size achieved a higher SFR (88.57% vs. 70.59%, p = 0.041) and a greater deflection angle than the 12.5 F inside diameter size. No significant variations were observed in the operative duration, hospitalization duration and the occurrence of SIRS between the compared cohorts.

CONCLUSION

TFS-UAS significantly improves SFR in FURL treatment of unilateral upper urinary tract calculi, particularly for stones located in the lower calyx or with a cumulative diameter of 2 cm or greater, compared to T-UAS.

Optimal deflection techniques for flexible and navigable suction ureteral access sheaths (FANS): a comparative in vitro PEARLS analysis

PURPOSE

Flexible and navigable suction ureteral access sheaths (FANS) have been introduced without current evidence on how to optimize deflection. Aim was to evaluate in vitro deflection angles with 2 different FANS techniques-sheath advancement and ureteroscope deflection; and effects of sheath size-ureteroscope combinations.

METHODS

We evaluated in vitro deflection angles of 10/12Fr, 11/13Fr and 12/14Fr FANS (Hunan Reborn Medical Co. Ltd) with six single-use flexible ureteroscopes (Pusen Uscope 7.5Fr, OTU WiScope 7.5Fr, OTU WiScope 8.6Fr, Innovex EU-scope 8.7Fr, Red Pine RP-U-C12 8.7Fr and Boston Scientific Lithovue 9.5Fr). Two deflection techniques were tested: (1) sheath advancement-advancing the sheath forward over a maximally deflected ureteroscope, and (2) ureteroscope deflection-maximally deflecting the ureteroscope from various starting positions relative to tip of the sheath.

RESULTS

Intra and inter-scope comparisons of maximum deflection angles were significantly different (all ANOVA p < 0.01). Largest maximum angles for all ureteroscopes were with the sheath advancement technique (range 218°-277°), and second largest for most scopes using the ureteroscope deflection technique at tip (range 111°-212°), mostly deviating from manufacturer specifications (range 270°-275°). 10/12Fr and 11/13Fr sheath sizes were more flexible than 12/14Fr. Largest angles were with 11/13Fr sheath-OTU8.6Fr/Innovex8.7Fr combinations.

CONCLUSION

Optimal deflection with FANS is achieved using either a sheath advancement technique, or ureteroscope deflection technique at tip. Despite using these optimized techniques, deflection angles specified by manufacturers seem hardly achievable. The sheath advancement technique and 11/13Fr sheath-OTU8.6Fr/Innovex8.7Fr combinations may be better suited for lower pole situations. Urologists should be aware of these differences and apply the findings to their FANS technique.

Assessment of Intrarenal Pressure through Dilatation State of the Renal Collecting System

INTRODUCTION

The aim of the study was to explore the relationship between the dilation states of the renal collecting system in flexible ureteroscopy (f-URS) view and intrarenal pressure (IRP).

METHODS

Fifteen porcine kidneys were randomly selected and numbered 1 through 15. Pressure transducers were inserted into the renal calyx via puncture and adjusted to a zero position. The distal end of the f-URS probe was placed within the renal pelvis. Perfusion rates of 50 mL/min, 80 mL/min, and 100 mL/min were utilized. We observed the relationship between the dilation state of the renal collecting system and changes in IRP. The state of complete dilation was defined as an unchanging spatial morphology of the renal collecting system as visualized during f-URS.

RESULTS

With irrigation rates of 50 mL/min, 80 mL/min, and 100 mL/min, IRP values at the moment of complete dilation of the renal collecting system ranged from 16 to 18 cm H2O, 16-19 cm H2O, and 16-19 cm H2O, respectively. Maximum IRPs ranged from 47 to 49 cm H2O, 82-85 cm H2O, and 97-100 cm H2O, respectively. Prior to complete dilation of the renal collecting system, IRP consistently remained below 20 cm H2O. However, following full dilation of the renal collecting system, IRP rose rapidly and rapidly surpassed 20 cm H2O. Despite sustained elevations in IRP following full dilation, no significant alterations in the renal collecting system dilated morphological were observed with f-URS.

CONCLUSIONS

In vitro experiments indicate that when the renal collecting system is not fully dilated, the IRP is consistently less than 20 cm H2O. Evaluation of IRP being within a safe range can be determined by assessing the dilation status of the renal collecting system.

Intelligent control of pressure based on ureteral access sheaths: renal pelvic pressure during flexible ureteroscope perfusion at different sites

OBJECTIVE

This study aimed to evaluate the accuracy and effectiveness of renal pelvic pressure (RPP) control during flexible ureteroscopic perfusion at various sites.

METHODS

Flexible ureteroscopy for the intelligent control of RPP was based on a ureteral access sheath (UAS) that integrated pressure measurement and suction functions (with automatic adjustment). Eleven consecutive patients with indurating nephrostomy tubes were enrolled. The nephrostomy tube was connected to a disposable invasive blood pressure sensor. The RPP was zeroed after the pressure stabilized. The flow rate and control value were set at 100 ml/min and - 5 mmHg, respectively. An 8.5 Fr flexible ureteroscope was irrigated at the renal pelvis, as well as the upper, middle, and lower calyces of the kidney for 1 min.

RESULTS

All 11 patients with upper urinary tract calculi underwent successful UAS placement. Pressures measured by the sheath and fistula during perfusion were - 5.07 ± 1.41 and - 4.89 ± 1.07 mmHg at the renal pelvis, -5.16 ± 1.36 and - 5.12 ± 1.32 mmHg at the upper calyces, -4.98 ± 0.87 and - 5.39 ± 1.01 mmHg at the middle calyces, as well as -4.95 ± 1.56 and - 5.64 ± 1.24 mmHg at the lower calyces, respectively. There were no significant differences in pressure between the sheath and fistula groups or in sheath and fistula pressures among parts. The RPP fluctuated; however, all values were within the safe limit of 20 mmHg.

CONCLUSION

The UAS-based pressure monitoring technology can accurately and reliably monitor and control RPP within a set range.

Suction use in ureterorenoscopy: A systematic review and meta-analysis of comparative studies

Objectives

Ureterorenoscopy is seeing a bloom of technological advances, one of which is incorporating suction. The objective of this study is to systematically review existing literature regarding suction use in rigid and flexible ureterorenoscopy and perform meta-analysis of studies comparing suction versus no suction ureteroscopy or mini percutaneous nephrolithotomy (PCNL).

Methods

A literature search was performed (November 2023) in MEDLINE, Embase and Cochrane CENTRAL. Study protocol was registered at PROSPERO (CRD42023482360). Comparative studies (observational and randomized) were eligible for inclusion if they compared suction versus no suction group and reported at least one primary outcome of interest (stone-free or complication rate).

Results

Sixteen studies (5 randomized and 11 observational), analysing 1086 and 1109 patients in standard and suction groups, respectively, were included. Final stone-free rates (SFRs), overall and infectious complications and length of hospital stay exhibited significant improvement when suction was used. When mini-PCNL was compared with flexible ureterorenoscopy with suction, no differences were found in terms of stone-free and infectious complications rates.

Conclusions

Ureterorenoscopy is a commonly performed endoscopic procedure for urolithiasis treatment, the success of which is defined by SFRs and complication rates. Application of suction via ureteral access sheaths, ureteral catheters or scopes may provide improved SFRs, reduced overall and infectious complication rates, along with a reduction in length of hospital stay. Further randomized studies are needed to validate these findings and standardize indications and protocols.

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.