Precision Stone Surgery: Current Status of Miniaturized Percutaneous Nephrolithotomy

Vacuum-assisted access sheath in supine mini-percutaneous nephrolithotomy (mini-PCNL)

INTRODUCTION

The vacuum-assisted access sheath is a new device for the treatment of kidney stones with percutaneous nephrolithotomy (PCNL).

OBJECTIVE

Our aim was to compare the stone-free rate (SFR) and complications between standard mini percutaneous nephrolithotomy (Mini-PCNL) and vacuum-assisted PCNL (Va-PCNL).

METHODS

Retrospective study of patients undergoing Mini-PCNL and Va-PCNL from January 2018 to June 2022. Va-PCNL was performed with a disposable sheath (ClearPetra®) with continuous high-flow irrigation and vacuum fluid dynamics for easier stone fragment removal. Baseline patient characteristics, surgical outcomes, perioperative and postoperative data were collected. We compared SFR and complications.

RESULTS

A total of 136 patients were identified, 57 (41,9%) underwent Va-PCNL and 79 (58,15%) Mini-PCNL. Mean operative time was significantly shorter in the Va-PCNL group (95 min.) than in Mini-PCNL (146 min; P = ,001) group. The tubeless technique was performed more frequently in Va-PCNL group (61,4% vs. 34,2%; P = ,002). We did not observe any differences in postoperative complications. The mean hospital stay was significantly lower in Va-PCNL with 1,7 ± 1,9 days per patient compared with 2,7 ± 1,5 days in the Mini-PCNL group (P = ,001). There were no differences in SFR at 3 months between Va-PCNL (71,9%) and Mini-PCNL (71,8%; P =v ,848).

CONCLUSION

Patients treated with Va-PCNL had comparable results to Mini-PCNL, showing equal SFR with similar infectious complications rates. Potential benefits of Va-PCNL include shorter operative time and postoperative stay.

Paediatric percutaneous nephrolithotomy (P-PCNL) reporting checklist

OBJECTIVE

To develop a reporting checklist that serves to improve and standardise reporting in studies pertaining to paediatric percutaneous nephrolithotomy (PCNL).

METHODS

Based on findings from systematic review of literature, a draft list of items was formulated. By process of review and revisions, a finalised version was established and consensus achieved.

RESULTS

The finalised version of the checklist covers four main sections, which include the following areas: study details, pre-operative, operative and post-operative information. There are 18 further sub-items. Recommendations deemed to be of high importance to include are highlighted in bold.

CONCLUSION

This practical tool can aid clinicians and researchers when undertaking and reviewing studies on paediatric PCNL. This is highly relevant given the current heterogeneity that exists as well as debate in best practice patterns.

Efficacy and safety of minimally invasive percutaneous nephrolithotomy versus retrograde intrarenal surgery in the treatment of upper urinary tract stones (> 1 cm): a systematic review and meta-analysis of 18 randomized controlled trials

BACKGROUND

The advantages and disadvantages of retrograde intrarenal surgery (RIRS) and minimally invasive percutaneous nephrolithotomy (mPCNL) for treatment of upper urinary tract calculi have not been conclusively determined.

METHODS

In this meta-analysis, We comprehensively evaluated the performance of the two surgical approaches in treatment of upper urinary calculi. We searched the Pubmed, Embase, Cochrane and Web of science databases for randomized controlled trial (RCT) articles on RIRS and mPCNL upto December 2022. Data were extracted by two independent reviewers and subjected to the meta-analysis using the Stata 15.1 software (StataSE, USA).

RESULTS

A total of 18 eligible RCTs involving 1733 patients were included in this study. The meta-analysis revealed that mPCNL of 1-2 cm or 2-3 cm stones had a higher stone clearance rate (RR:1.08, 95%CI (1.03, 1.14), p = 0.002) and shorter operation time (WMD : -10.85 min, 95%CI (-16.76, -4.94), p<0.001). However, it was associated with more hospital stay time (WMD :1.01 day, 95%CI(0.53, 1.5), p<0.001), hemoglobin drops (WMD :0.27 g/dl, 95%CI (0.14, 0.41), p<0.001), blood transfusion rate (RR:5.04, 95%CI(1.62, 15.65), p = 0.005), pain visual analogue score (WMD:0.75, 95%CI (0.04, 1.46), p = 0.037), hospital costs (SMD :-0.97, 95%CI (-1.19, -0.76), p<0.001) and major complications (RR:1.89, 95%CI(1.01, 3.53), p = 0.045).

CONCLUSION

Therefore, in terms of surgical effects and operation time, mPCNL is superior to RIRS, but is inferior with regards to other perioperative parameters. These factors should be fully considered in clinical decision making.

Pattern of key opinion leaders talks at major international urological meetings reflects the main differences in flexible ureteroscopy and PCNL diffusion

OBJECTIVE

To analyze the pattern of speaker activity related to both flexible ureteroscopy (fURS) and percutaneous nephrolithotomy (PCNL) during plenary sessions at the main (endo)urological international meetings over the last 10 years.

METHODS

We reviewed the meeting programs of the main endourological international meetings (EAU, AUA, WCE, and SIU) during 2011-2019. We detected all invited speakers at plenary sessions regarding fURS or PCNL. The proportion of fURS and PCNL talks was evaluated yearly during the study period. In order to analyze plenary session speaker composition, we estimated and compared the mean number of talks per speaker according to surgical technique. We also analyzed possible differences in age distribution according to the topic of the talk as well as the presence of young (i.e., < 45 years) speakers. Data were analyzed using descriptive statistics.

RESULTS

During the last 10 years, a total of 498 plenary talks were found. Of those, 260 (52.2%), 211 (42.4%), and 27 (5.4%) discussed PCNL, fURS, or both, respectively. PCNL was more frequently discussed at the beginning and the end of the study period. Mean [SD] number of talks per speaker was higher for PCNL (2.9 [3.4] vs 1.6 [1.4], p < 0.001), meaning that a wider variety of speakers was invited to give fURS talks. Speakers discussing fURS were younger (median [interquartile range, IQR] age 48 [44-56] vs 52 [47-60] years, p < 0.001), and a higher proportion of young speakers was observed in the fURS group (26% vs 15% p < 0.001). PCNL speakers were more commonly discussing fURS than fURS speakers discussing PCNL (23% vs 17%, p = 0.43).

CONCLUSIONS

We found a wider variety of speakers at fURS plenary sessions as compared to PCNL ones. It is easier and quicker to become an internationally recognized expert in the field of fURS rather than PCNL. PCNL speakers were able to master fURS more frequently than the other way around.

Paediatric kidney stone surgery: state-of-the-art review

While urolithiasis in children is rare, the global incidence is rising, and the volume of minimally invasive surgeries being performed reflects this. There have been many developments in the technology, which have supported the advancement of these interventions. However, innovation of this kind has also resulted in wide-ranging practice patterns and debate regarding how they should be best implemented. This is in addition to the extra challenges faced when treating stone disease in children where the patient population often has a higher number of comorbidities and for example, the need to avoid risk such as ionising exposure is higher. The overall result is a number of challenges and controversies surrounding many facets of paediatric stone surgery such as imaging choice, follow-up and different treatment options, for example, medical expulsive therapy, shockwave lithotripsy, ureteroscopy, and percutaneous nephrolithotomy. This article provides an overview of the current status of paediatric stone surgery and discussion on the key topics of debate.

Totally X-ray-Free Ultrasound-Guided Mini-Percutaneous Nephrolithotomy in Galdakao-Modified Supine Valdivia Position: A Novel Combined Surgery

We introduced a novel surgery that combines ultrasound guidance, miniaturization and Galdakao-modified supine Valdivia (GMSV) position in percutaneous nephrolithotomy (PCNL) and evaluated the safety and efficacy. This retrospective, single-center study retrospectively reviewed 150 patients who underwent ultrasound-guided mini-PCNL in the GMSV position from November 2019 to March 2022. All perioperative parameters were collected. Stone-free status was defined as no residual stones or clinically insignificant residual fragments (CIRF) <0.4 cm on postoperative day one. Among the 150 patients, the mean age was 56.96 years. The mean stone size was 3.19 cm (427 mm2). The mean S.T.O.N.E. score was 7.61, including 36 patients (24%) with scores ≥9. The mean operative time was 66.22 min, and the success rate of renal access creation in the first attempt was 88.7%. One hundred and forty (93.3%) patients were stone free. The mean decrease in Hemoglobin was 1.04 g/dL, and no patient needed a blood transfusion. Complications included transient hematuria (n = 13, 8.7%), bladder blood clot retention (n = 2, 1.3%), fever (n = 15, 10%) and sepsis (n = 2, 1.3%). Totally X-ray-free ultrasound-guided mini-PCNL in the GMSV position is feasible, safe and effective for patients with upper urinary tract stones, indicating the synergistic and complementary effects of the three novel techniques.

Comparison of postoperative outcomes of mini percutaneous nephrolithotomy and standard percutaneous nephrolithotomy: a meta-analysis

Our study was aimed to evaluate the postoperative outcomes of Mini Percutaneous Nephrolithotomy (Mini-PCNL) and Standard Percutaneous Nephrolithotomy (Standard-PCNL) to determine the optimum option for patients with renal calculi. For publications published between January 2010 and April 2021, a comprehensive search of the PubMed, Cochrane Library, Web of Science, and EMBASE databases was done. The literatures were chosen based on the criteria for inclusion and exclusion. After the data were retrieved and the quality was assessed, the meta-analysis was performed using Review Manager Software (RevMan 5.4.1, Cochrane Collaboration, Oxford, UK). We selected 20 trials with a total of 4953 people out of 322 studies. There were 2567 patients treated with Mini-PCNL and 2386 patients treated with Standard-PCNL. Meta-analysis results showed no difference in stone-free rates (SFR, P = 0.93), fever (P = 0.83), and postoperative pain (VAS score) (P = 0.21) between Mini-PCNL and Standard-PCNL. Patients in the Mini-PCNL group experienced shorter hospital stay (P < 0.0001), less hemoglobin drop (P < 0.00001), less blood transfusion (P < 0.00001), higher postoperative tubeless (P = 0.0002), and fewer complications including bleeding (P = 0.01), perforation (P = 0.03), and leakage (P = 0.01). Compared with Standard-PCNL, operative time was longer in the Mini-PCNL group (P = 0.0005). Mini-PCNL had a shorter hospital stay, less hemoglobin drop, less blood transfusion, greater postoperative tubeless, fewer complications, and a longer operational time when compared to Standard-PCNL. SFR, fever, and postoperative pain were similar in both of them. Mini-PCNL may be a superior option for patients with proper size renal calculi.

Benchtop Evaluation of Miniature Percutaneous Nephrolithotomy Lithotrites

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is the preferred treatment for kidney stones >2cm. While PCNL has traditionally been performed using 24-30Fr access sheaths, there is a trend toward smaller sheaths and scopes to perform mini-PCNL (mPCNL). We performed benchtop assessment of multiple mPCNL lithotrites.

METHODS

One 1cm3, hard Begostone phantom was placed in a cylinder with four 5.5mm cylindrical openings to simulate the size of a 16.5Fr mPCNL sheath. Lithotripsy was performed with the 1.5mm and 1.9mm Trilogy, 1.83mm ShockPulse, or a 200m Holmium:YAG laser. Suction was used for the mechanical lithotrites. The Trilogy probes were set at 50% impact, 6Hz, 80% ultrasound and 10% suction. The ShockPulse was used at high-power setting with low suction. The 1.9mm Trilogy probe was used with a 15Fr mini-nephroscope. The 1.83mm ShockPulse, 1.5mm Trilogy and laser fiber were used with a 12Fr mini-nephroscope. The 120 W holmium laser was set at 0.5J/70Hz Moses-Distance. Ten independent runs were performed with modality. Time to complete stone clearance was recorded and mass stone clearance rates were calculated.

RESULTS

The Trilogy 1.9mm showed superior stone clearance rate (11.69 ± 3.68 mg/s) vs the SP 1.83mm (6.29 ± 1.37 mg/s, p=0.003), the laser fiber (4.73 ± 0.61 mg/s, p<0.0005), and the Trilogy 1.5mm (6.84± 1.21 mg/s). The 200m laser fiber was inferior to all mechanical lithotrites. There was no difference between the 1.5mm Trilogy and the 1.83mm ShockPulse (p=0.772). This translates to 3.9, 4.8 and 8.1 minutes less treatment time vs the 1.5mm Trilogy, SP, and laser, respectively, for a spherical 1.5cm diameter calcium oxalate monohydrate stone.

CONCLUSION

Among these four commonly used mPCNL lithotripters, the Trilogy 1.9 mm demonstrated superior stone clearance rates in this benchtop model versus the Ho:YAG laser, 1.83mm SP, and Trilogy 1.5mm. Future clinical testing is warranted to evaluate the optimal lithotrite for mPCNL.

Urologists are optimistic surgeons: prevalence and predictors of discordance between intraoperative stone-free rate and cross-sectional imaging evaluation after vacuum-assisted mini-percutaneous nephrolithotomy

Purpose

To assess how accurate are urologists in predicting stone-free status (SFS) after vacuum-assisted mini-PCNL (vamPCNL) compared to computed tomography (CT) and clinical predictors of discordant SFS.

Methods

Data from 235 patients who underwent vamPCNL were analysed. Patient’s demographics, stones’ characteristics and operative data were recorded. SFS was evaluated intraoperatively by the treating urologist (iSFS) and with non-contrast CT 3 months after vamPCNL (ctSFS). SFS was defined as no residual stones. Stone complexity was scored with the Guy’s score. Descriptive statistics and logistic regression models were used to identify clinical factors associated with discordant SFS (namely iSFS not confirmed at CT).

Results

iSFS and ctSFS were 88.5% and 65.5%, respectively, with 54 (23%) cases resulting in discordant evaluation of SFS between the surgeon and CT imaging. Patients with discordant SFS had larger stone volume (p < 0.001), higher rate of multiple stones (p = 0.03) and higher rate of multiple calyceal groups affected by stones (p < 0.001) than those with concordant SFS. The use of flexible ureteroscopes to look for residual stones after lithotripsy was more frequently reported in cases with concordant SFS (p = 0.001). Multivariable logistic regression analysis revealed that stones in > 2 calyceal groups (OR 10.2, p < 0.001), Guy’s score II (OR 5.8, p < 0.01) and not using flexible ureteroscopes after lithotripsy (OR 2.9, p = 0.02) were independent predictors of discordant SFS.

Conclusion

One out of five patients is erroneously considered SF after vamPCNL. Urologist should carefully evaluate patients with multiple calyceal stones and consider using flexible ureteroscopes to complete lapaxy of migrated fragments in order to improve their prediction of SFS.

Clinical study on the minimally invasive percutaneous nephrolithotomy treatment of upper urinary calculi

BACKGROUND

Upper urinary tract stones are very common in my country, with an incidence of 1% to 5% in the North and an even higher incidence of 5% to 10% in the south. The incidence rate in the south is higher than that in the north, mainly due to the water quality, climate and eating habits of the region. From the perspective of sex, incidence is more likely in males than females. In the high-incidence population, young adults are most prone to stones. Men in the age range of 25 to 40 years are more likely to have stones.

AIM

To observe the therapeutic effect of minimally invasive percutaneous nephrolithotomy (mPCNL) on upper urinary tract stones and its influence on the renal function of patients.

METHODS

Patients with upper urinary tract stones who were treated in our hospital from February 2017 to March 2018 were selected as research subjects and were divided into the PCNL group and the mPCNL group according to the random number table method. The general conditions of the two groups of patients were observed during the perioperative period, and the differences in stone clearance, pain, renal function indicators and complication rates were compared between the two groups to determine which were statistically significant (P < 0.05).

RESULTS

The operation time of the mPCNL group was longer than that of the PCNL group (t = -34.392, P < 0.001), and the intraoperative blood loss of the mPCNL group was more than that of the PCNL group (t = 34.090, P < 0.001). There was no difference in renal function indices between the two groups of patients before treatment, and there was no difference in the levels of serum creatinine, β2 microglobulin or retinol binding protein in the mPCNL group after treatment. The visual analog scale score of patients in the mPCNL group was lower than that of the PCNL group (t = 12.191, P < 0.001), and there was no significant difference in the stone clearance rate between the two groups (χ² value = 1.013, P = 0.314). There was no significant difference in the incidence of urine extravasation, dyspnea and peripheral organ damage between the two groups (χ² value = 1.053, P = 0.305). At 1 mo after treatment and 3 mo after treatment, the quality of life of the mPCNL group was lower than that of the PCNL group, and the Qmax level of the mPCNL group was higher than that of the PCNL group.

CONCLUSION

mPCNL has a good therapeutic effect on upper urinary tract stones, with a high stone clearance rate without causing kidney damage or increasing the incidence of complications, and thus has good application value.

Minimally invasive surgery for pediatric renal and ureteric stones: A therapeutic update

The incidence of pediatric urolithiasis (PU) is growing worldwide. The corresponding therapeutic methods have become a research hot spot in pediatric urology. PU has the characteristics of abnormal metabolism, easy recurrence, and immature urinary system development, which make its treatment different from that of adults. Pediatric urologists should select the optimal treatment modality to completely remove the stones to prevent recurrence. Currently, the curative treatments of PU include extracorporeal shock wave lithotripsy (ESWL), ureteroscopy, retrograde intrarenal surgery, percutaneous nephrolithotomy (PCNL), laparoscopic, robot-assisted laparoscopic, and open surgery. This review aims to conduct a therapeutic update on the surgical interventions of both pediatric renal and ureteric stones. It accentuates that pediatric surgeons or urologists should bear in mind the pros and cons of various minimally invasive surgical treatments under different conditions. In the future, the treatment of PU will be more refined due to the advancement of technology and the development of surgical instruments. However, a comprehensive understanding of the affected factors should be taken into account by pediatric urologists to select the most beneficial treatment plan for individual children to achieve precise treatment.