Contemporary ureteroscopic management of renal stones

Evaluating the learning curve for flexible ureteroscopic thulium fiber laser lithotripsy using CUSUM analysis

OBJECTIVES

Effective training methods and learning curve (LC) assessment are crucial for more difficult endoscopic procedures. The present study sought to assess the LC of flexible ureteroscopes (fURS) for thulium fiber laser (TFL) lithotripsy and determine the effectiveness of using a porcine kidney model in training modality, to inform future training.

METHODS

Postgraduate medical students without experience in ureteroscopy were recruited, and surgical data were collected from 10 consecutive flexible ureteroscopic lithotripsy (fURL) procedures performed on our homemade porcine kidney training model. Cumulative sum (CUSUM) analysis and pooled mean CUSUM curves were applied to determine the LC turning points (TPs), and pre-LC and post-LC data were compared with that of an experienced attending physician.

RESULTS

Data from 110 surgeries were included in the analysis. The mean number of surgical units to overcome the LC for the duration of fURS TFL lithotripsy was 4. The operation time, number of tissue damage, and number of central visual shifts were significantly lower in students after the TP than before. No statistically significant difference in operation time was found between the students after the LC (817.50 [703.75-964.75]) and the surgeon group (732.50 [51.00-822.25]).

CONCLUSION

Overcoming the LC of fURS TFL lithotripsy requires four surgeries, and the developed ex vivo porcine kidney is a conveniently accessible and effective clinical training model.

Effects of Ciprofol and Propofol General Anesthesia on Postoperative Recovery Quality in Patients Undergoing Ureteroscopy: A Randomized, Controlled, Double-Blind Clinical Trial

Objective

This study compares postoperative recovery quality between Ciprofol and Propofol, providing a reference for the clinical application of anesthetics.

Methods

We randomized 112 patients undergoing ureteroscopic surgery into two groups: the Ciprofol group (Group C), with an induction dose of 0.4 mg/kg and a maintenance dose of 0.8-1.5 mg/(kg·h), and the Propofol group (Group P), with an induction dose of 2 mg/kg and a maintenance dose of 4-10 mg/(kg·h). Both groups received sevoflurane at a concentration of 1%. The Bispectral Index (BIS) was maintained between 40 and 60. The primary outcomes were the Quality of Recovery-15 (QoR-15) scores on postoperative day 1 (POD1). Secondary outcomes included hemodynamic parameters, vasopressor use, timing indicators, sedative consumption, BIS values, Riker Sedation-Agitation Scale (R-SAS) scores, urinary tract symptoms, patient satisfaction, and adverse events.

Results

No significant differences were observed in QoR-15 scores between the two groups. Although Group C had higher pain (P = 0.004) and comfort (P = 0.002) scores on POD1, these differences were not clinically significant. The incidence of hypotension and vasopressor use was lower in Group C, which had more stable hemodynamics. Additionally, the time from induction to BIS ≤ 60 was shorter in Group P (P = 0.001), while Group C had lower BIS values from drug discontinuation to full recovery of consciousness (P = 0.001). The incidence of urinary tract symptoms on POD1 was lower in Group C (P = 0.043). There were no significant differences in time to spontaneous breathing recovery, extubation, recovery room stay, time to first ambulation, hospital stay, patient satisfaction, or other adverse events.

Conclusion

Ciprofol provides comparable early postoperative recovery to Propofol during ureteroscopy and may be a preferable alternative for urological procedures, especially in patients with blood pressure concerns.

Trial Registration

Chinese Clinical Trial Registry (ChiCTR2400082736).

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.

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.

The identification of key molecules and pathways in the crosstalk of calcium oxalate-treated TCMK-1 cells and macrophage via exosomes

The interplay between crystals and epithelial cells forms the cornerstone of kidney stone development, communication between epithelial cells and macrophages emerging as a pivotal role in this process. We conducted next-generation sequencing on the secreted exosomes of TCMK-1 cells treated with calcium oxalate monohydrate (OX_EXO) or controls (NC_EXO), and on the macrophage cell line RAW264.7 stimulated with OX_EXO or NC_EXO, followed by validation of differentially expressed target proteins and miRNAs through Western blot and PCR. UPSET plots were employed to identify genes co-targeted by exosomal miRNAs. Various bioinformatic analyses were employed to predict potential mechanisms of the dysregulated genes. We integrated sequencing data from the GEO database, and validated findings using clinical patient urine and kidney tissues. We identified 665 differentially expressed exosomal miRNAs between OX_EXO and NC_EXO. Among the top 10 down-regulated miRNAs, the most targeted genes were AAK1 and NUFIP2, whereas PLCB1 was significantly targeted among the top 10 up-regulated miRNAs. In clinical specimens, we confirmed the differential expressions of five homologous miRNAs, as well as CNOT3, CNCNA1C, APEX1, and TMEM199. In conclusion, treatment of TCMK-1 cells with calcium oxalate significantly alerted the expression profile of exosomal miRNAs, subsequently influencing gene expression in macrophages, thereby modulating the processes of kidney stone formation.

Autofluorescence spectral analysis for detecting urinary stone composition in emulated intraoperative ambient

The prevalence and disease burden of urolithiasis has increased substantially worldwide in the last decade, and intraluminal holmium laser lithotripsy has become the primary treatment method. However, inappropriate laser energy settings increase the risk of perioperative complications, largely due to the lack of intraoperative information on the stone composition, which determines the stone melting point. To address this issue, we developed a fiber-based fluorescence spectrometry method that detects and classifies the autofluorescence spectral fingerprints of urinary stones into three categories: calcium oxalate, uric acid, and struvite. By applying the support vector machine (SVM), the prediction accuracy achieved 90.28 % and 96.70% for classifying calcium stones versus non-calcium stones and uric acid versus struvite, respectively. High accuracy and specificity were achieved for a wide range of working distances and angles between the fiber tip and stone surface in an emulated intraoperative ambient. Our work establishes the methodological basis for engineering a clinical device that achieves real-time, in situ classification of urinary stones for optimizing the laser ablation parameters and reducing perioperative complications in lithotripsy.

Real Time Intrarenal Pressure Control during Flexible Ureterorrenscopy Using a Vascular PressureWire: Pilot Study

(1) Introduction: To evaluate the feasibility of measuring the intrapelvic pressure (IPP) during flexible ureterorenoscopy (f-URS) with a PressureWire and to optimize safety by assessing IPP during surgery. (2) Methods: Patients undergoing f-URS for different treatments were recruited. A PressureWire (0.014", St. Jude Medical, Little Canada, MN, USA) was placed into the renal cavities to measure IPP. Gravity irrigation at 40 cmH₂O over the patient and a hand-assisted irrigation system were used. Pressures were monitored in real time and recorded for analysis. Fluid balance and postoperative urinary tract infection (UTI) were documented. (3) Results: Twenty patients undergoing f-URS were included with successful IPP monitoring. The median baseline IPP was 13.6 (6.8-47.6) cmH₂O. After the placement of the UAS, the median IPP was 17 (8-44.6) cmH₂O. With irrigation pressure set at 40 cmH₂O without forced irrigation, the median IPP was 34 (19-81.6) cmH₂O. Median IPP during laser lithotripsy, with and without the use of on-demand forced irrigation, was 61.2 (27.2-149.5) cmH₂O. The maximum pressure peaks recorded during forced irrigation ranged from 54.4 to 236.6 cmH₂O. After the surgery, 3 patients (15%) presented UTI; 2 of them had a positive preoperative urine culture, previously treated, and a positive fluid balance observed after the surgery. (4) Conclusion: Based on our experience, continuous monitoring of IPP with a wire is easy to reproduce, effective, and safe. In addition, it allows us to identify and avoid high IPPs, which may affect surgery-related complications.

Comparison of the effects of retroperitoneoscopic ureterolithotomy and ureteroscopic lithotripsy in the treatment of upper ureteral calculi

ABSTRACT

This study compares the efficacy of retroperitoneoscopic ureterolithotomy (RPUL) and ureteroscopic lithotripsy (URL) in the treatment of upper ureteral calculi.The clinical data of 150 patients with upper ureteral calculi who underwent RPUL and 136 patients who underwent URL between January 2014 and October 2019 were retrospectively analyzed. The operation time, postoperative hospital stay, operation success rate, stone clearance rate, and surgical complications were evaluated between the two groups.For the RPUL and URL groups, respectively, the average operation time was 74.5 ± 24.6 minutes and 54.5 ± 13.2 minutes; the postoperative hospital stay was 5.8 ± 1.4 days and 3.2 ± 1.2 days; the operation success rate was 96.0% (144/150) and 85.3% (116/136); the incidence rate of complications was 3.5% (5/144) and 17.5% (18/103); and the stone clearance rate was 100% (144/144) and 88.8% (103/116), which were all statistically significant (P < .05).Both RPUL and URL had the advantages of low trauma and fast recovery rate for patients with upper ureteral calculi. However, patients who underwent RPUL showed higher success and fewer complication rate. RPUL might be a safe and effective laparoscopic method for the treatment of patients with upper ureteral calculi.

Factors Influencing Surgical Outcome in Retrograde Management of Parapelvic Renal Cysts

Objective: To investigate the outcomes of retrograde flexible ureteroscopy in managing parapelvic renal cysts and speculate the factors affecting therapeutic efficacy. Methods: Thirty-eight patients with parapelvic renal cysts were recruited and underwent retrograde flexible ureteroscopy using holmium laser. Parapelvic cysts were divided into peripheral type and central type based on the position of cyst convex to the perirenal tissue. Feasibility and safety were retrospectively evaluated, and cases were analyzed to detect their distinctive characteristics. Independent-sample t-test and chi-square test were undertaken for continuous variables and categorical variables, respectively. Results: Radiologic evidence of success was achieved in 31 (81.58%) cases after a mean follow-up of 14.4 months (range 6-26 months). No significant perioperative complications were identified. There were seven cases with features of peripherally located parapelvic cyst. Four cysts shown as irregular protrusion were unable reduce to less half of previous size. Reductions were recorded in the other three patients with spherically peripheral protrusion. There was significant difference between these two types (p = 0.029). Among the 31 patients with centrally located parapelvic cyst, 28 of these have simple cysts that achieved radiologic success and 3 of the 31 patients were identified as failed cases indicated by renal pelvis enveloped by cyst on radiologic investigation. The success rate of simple cysts was significantly higher than that of the later type (p < 0.001). Conclusion: The location and shape of parapelvic cyst may play a critical role in the radiologic outcome of internal incision and patients with simple central or spherical peripheral cyst may benefit more from retrograde flexible ureteroscopy combined with laser incision.

Outcomes of ureteroscopy (URS) for stone disease in the paediatric population: results of over 100 URS procedures from a UK tertiary centre

PURPOSE

To report the outcomes of paediatric ureteroscopy (URS) for stone disease from a specialist endourology centre in the UK. Ureteroscopy for management of stone disease has increased worldwide and is now being done more commonly in the paediatric age group.

METHODS

Data were analysed retrospectively from a database maintained between April 2010 and May 2018. Consecutive patients ≤ 16 years of age undergoing semi-rigid or flexible URS for stone disease were included. Stone size and stone-free rate (SFR) were routinely assessed using an ultrasound (USS) and/or plain KUB XR. Complications were graded according to the Clavien-Dindo classification and recorded within 30 days post-procedure and readmissions within 90 days after the procedure were also captured.

RESULTS

Over the 8-year period between April 2010 and April 2018, 81 patients with a mean age of 8.8 years (range 18 months-16 years) and a male to female ratio 1:1.1 underwent 102 procedures (1.28 procedure/patient to be stone free). Of the 81 patients, 29 (35.8%) had comorbidities, with 26 (32%) having multiple comorbidities. The mean (± SEM) single and overall stone size was 9.2 mm (± 0.48, range 3-30 mm) and 11.5 mm (± 0.74, range 4-46 mm) respectively, with 22 (27.1%) having multiple stones. Thirty-five (34.7%) had stent in situ pre-operatively. The stone location was in the ureter (26.6%), lower pole (35.4%), and renal pelvis (16.5%), with 22/81(27%) having multiple stones and 21/102 (20.5%) where a ureteral access sheath (UAS) was used. With a mean hospital stay of 1.2 days, the initial and final SFR was 73% and 99%, respectively, and 61/102 (60%) had ureteric stent placed at the end of the procedure. While there were no intra-operative complications, the readmission rate was less than 1% and there were only three early complications recorded. This included a case each of prolonged admission for pain control (grade I), urinary retention (grade II) and post-operative sepsis requiring a brief ITU admission (grade IV).

CONCLUSION

Our study demonstrates that in appropriate setting a high stone-free rate can be achieved with minimal morbidity for paediatric patients. There is potentially a need to factor the increasing role of URS in future paediatric urolithiasis guidelines.

Tubeless versus standard percutaneous nephrolithotomy: an update meta-analysis

Background

To update a previously published systematic review and meta-analysis on the efficacy and safety of tubeless percutaneous nephrolithotomy (PCNL).

Methods

A systematic literature search of EMBASE, PubMed, Web of Science, and the Cochrane Library was performed to confirm relevant studies. The scientific literature was screened in accordance with the predetermined inclusion and exclusion criteria. After quality assessment and data extraction from the eligible studies, a meta-analysis was conducted using Stata SE 12.0.

Results

Fourteen randomized controlled trials (RCTs) involving 1148 patients were included. Combined results demonstrated that tubeless PCNL was significantly associated with shorter operative time (weighted mean difference [WMD], −3.79 min; 95% confidence interval [CI], −6.73 to −0.85; P = 0.012; I² = 53.8%), shorter hospital stay (WMD, −1.27 days; 95% CI, −1.65 to −0.90; P < 0.001; I² = 98.7%), faster time to return to normal activity (WMD, −4.24 days; 95% CI, −5.76 to −2.71; P < 0.001; I² = 97.5%), lower postoperative pain scores (WMD, −16.55 mm; 95% CI, −21.60 to −11.50; P < 0.001; I² = 95.7%), less postoperative analgesia requirements (standard mean difference, −1.09 mg; 95% CI, −1.35 to −0.84; P < 0.001; I² = 46.8%), and lower urine leakage (Relative risk [RR], 0.30; 95% CI 0.15 to 0.59; P = 0.001; I² = 41.2%). There were no significant differences in postoperative hemoglobin reduction (WMD, −0.02 g/dL; 95% CI, −0.04 to 0.01; P = 0.172; I² = 41.5%), stone-free rate (RR, 1.01; 95% CI, 0.97 to 1.05; P = 0.776; I² = 0.0%), postoperative fever rate (RR, 1.05; 95% CI, 0.57 to 1.93; P = 0.867; I² = 0.0%), or blood transfusion rate (RR, 0.79; 95% CI, 0.36 to 1.70; P = 0.538; I² = 0.0%). The results of subgroup analysis were consistent with the overall findings. The sensitivity analysis indicated that most results remained constant when total tubeless or partial tubeless or mini-PCNL studies were excluded respectively.

Conclusions

Tubeless PCNL is an available and safe option in carefully evaluated and selected patients. It is significantly associated with the advantages of shorter hospital stay, shorter time to return to normal activity, lower postoperative pain scores, less analgesia requirement, and reduced urine leakage.

Tubeless versus standard percutaneous nephrolithotomy: an update meta-analysis

BACKGROUND

To update a previously published systematic review and meta-analysis on the efficacy and safety of tubeless percutaneous nephrolithotomy (PCNL).

METHODS

A systematic literature search of EMBASE, PubMed, Web of Science, and the Cochrane Library was performed to confirm relevant studies. The scientific literature was screened in accordance with the predetermined inclusion and exclusion criteria. After quality assessment and data extraction from the eligible studies, a meta-analysis was conducted using Stata SE 12.0.

RESULTS

Fourteen randomized controlled trials (RCTs) involving 1148 patients were included. Combined results demonstrated that tubeless PCNL was significantly associated with shorter operative time (weighted mean difference [WMD], -3.79 min; 95% confidence interval [CI], -6.73 to -0.85; P = 0.012; I² = 53.8%), shorter hospital stay (WMD, -1.27 days; 95% CI, -1.65 to -0.90; P < 0.001; I² = 98.7%), faster time to return to normal activity (WMD, -4.24 days; 95% CI, -5.76 to -2.71; P < 0.001; I² = 97.5%), lower postoperative pain scores (WMD, -16.55 mm; 95% CI, -21.60 to -11.50; P < 0.001; I² = 95.7%), less postoperative analgesia requirements (standard mean difference, -1.09 mg; 95% CI, -1.35 to -0.84; P < 0.001; I² = 46.8%), and lower urine leakage (Relative risk [RR], 0.30; 95% CI 0.15 to 0.59; P = 0.001; I² = 41.2%). There were no significant differences in postoperative hemoglobin reduction (WMD, -0.02 g/dL; 95% CI, -0.04 to 0.01; P = 0.172; I² = 41.5%), stone-free rate (RR, 1.01; 95% CI, 0.97 to 1.05; P = 0.776; I² = 0.0%), postoperative fever rate (RR, 1.05; 95% CI, 0.57 to 1.93; P = 0.867; I² = 0.0%), or blood transfusion rate (RR, 0.79; 95% CI, 0.36 to 1.70; P = 0.538; I² = 0.0%). The results of subgroup analysis were consistent with the overall findings. The sensitivity analysis indicated that most results remained constant when total tubeless or partial tubeless or mini-PCNL studies were excluded respectively.

CONCLUSIONS

Tubeless PCNL is an available and safe option in carefully evaluated and selected patients. It is significantly associated with the advantages of shorter hospital stay, shorter time to return to normal activity, lower postoperative pain scores, less analgesia requirement, and reduced urine leakage.

Intraductal Laser Fiber Tip Fracture and Retrieval During Sialendoscopic Laser-Assisted Lithotripsy

Fragmentation of flexible laser fiber tips has been reported to occur during therapeutic bronchoscopy and urologic stone treatment. We report fragmentation of 200-µm single-use silica-based fibers during sialendoscopy-controlled Holmium:YAG laser treatment of a parotid and a submandibular stone. The technique employed to successfully retrieve the fiber tips is described in the context of identifying this potential complication from endoscopic management of sialolithiasis.

In Vitro Comparison of Maximum Pressure Developed by Irrigation Systems in a Kidney Model

Purpose: To evaluate in vitro the maximum pressure generated in an artificial kidney model when people of different levels of strengths used various irrigation systems. Materials and Methods: Fifteen people were enrolled and divided into three groups based on their strengths. Individual strength was evaluated according to the maximum pressure each participant was able to achieve using an Encore™ Inflator. The irrigation systems evaluated were as follows: T-Flow™ Dual Port, Hiline™, continuous flow single action pumping system (SAPS™) with the system close and open, Irri-flo II™, a simple 60-mL syringe, and Peditrol™. Each irrigation system was connected to URF-V2 ureteroscope, which was inserted into an artificial kidney model. Each participant was asked to produce the maximum pressure possible with every irrigation device. Pressure was measured with the working channel (WC) empty, with a laser fiber, and a basket inside. Results: The highest pressure was achieved with the 60 mL-syringe system and the lowest with SAPS continuous version system (with continuous irrigation open), compared to the other irrigation devices (p < 0.0001). Irrespective of the irrigation system, there was a significant difference in the pressure between the WC empty and when occupied with the laser fiber or the basket inside it (p < 0.0001). The stratification between the groups showed that the most powerful group could produce the highest pressure in the kidney model with all the irrigation devices in almost any situation. The exception to this was the T-Flow system, which was the only device where no statistical differences were detected among these groups. Conclusion: The use of irrigation systems can often generate excessive pressure in an artificial kidney model, especially with an unoccupied WC of the ureteroscope. Depending on the strength of force applied, very high pressure can be generated by most irrigation devices irrespective of whether the scope is occupied or not.