The "mini-perc" technique: a less invasive alternative to percutaneous nephrolithotomy

Prospective multicenter real-world outcomes of Suction Technology Utility in Mini-PCNL Study (STUMPS) in modern-day practice: formulation of the global STUMPS registry on behalf of the endourology section of the European Association of Urology and the suction mini-PCNL collaborative study group

PURPOSE

To present outcomes of a registry to understand the practice patterns, resource utilization, and nuances of suction mini-percutaneous nephron lithotripsy (SM-PCNL).

METHODS

Data from 30 centers in 21 countries were prospectively collected (March-November 2024). SM-PCNL was defined as PCNL using a suction nephrostomy sheath of size 14-22 Fr. with any lithotripsy device. There were no instructions on how to perform the surgical procedure. Stone features and stone-free status were assessed using an unenhanced CT scan. Data are presented as median/interquartile range and frequency/proportion.

RESULTS

1707 patients were included and 42.4% of them were males. Most were first-time stone formers. Median age was 50 years. Median stone volume was 1700 mm3. Surgery was commonly performed using a single access tract (92.9%) and in supine position (56.5%). The fluoroscopy-only puncture was used as the most common access (70.7%), followed by the combination of fluoroscopy and ultrasound (25.1%). Median operation time was 45 min. The most common sheath was Clearpetra (27.8%). Thulium fiber laser was the most frequent energy used (26.2%). A tubeless procedure with a stent was employed in 47.0% of cases. Most common complications were fever managed by observation (7.3%), fever requiring antibiotics (3.3%), blood transfusion (1.1%), and sepsis (0.2%). Median hospitalization was 3 days. 30-day CT scan showed zero fragments in 82.4% of patients. Reintervention was performed in 2.6% of cases.

CONCLUSIONS

This registry outlines the various equipment, peri-operative strategies, complications, and outcomes of SM-PCNL performed in real-world practice, providing valuable data on the nuances of performing such surgery.

Trilogy vs 100 W Ho:YAG Laser for Lithotripsy in Mini-Percutaneous Nephrolithotomy: Superior Stone-Free Rates in a Randomized Controlled Trial

OBJECTIVE

To compare the clinical outcomes of lithotripsy using the 100 W Ho:YAG laser and the Trilogy lithotripter in Mini-percutaneous nephrolithotomy (PCNL), and to determine the most effective method for stone clearance through a miniaturized percutaneous tract.

METHODS

This double-blind, randomized, single-center controlled trial (Clinicaltrials.gov ID: NCT04559321) enrolled patients with GUY's grade 1-2 kidney stones. Participants were randomly assigned to undergo Mini-PCNL using either the 100 W Ho:YAG laser (Lumenis Pulsed 100H) or the 1.5 mm Trilogy lithotripter (EMS-Nyon). Primary endpoints were stone lithotripsy time (SLT), lithotripsy rate (SLR), and stone-free rate (SFR). SLT was defined as the time from first activation of the lithotripter/laser until no further activations were needed. The study was terminated early in August 2023 following DSMB recommendations due to evidence of efficacy in one arm.

RESULTS

Eighty-three patients were analyzed (Laser, n=40; Trilogy, n=43), with comparable demographic and stone characteristics. Mean SLT was 8.02 minutes (Laser) vs 5.7 minutes (Trilogy, P=.199). SLR was 179 vs 212 mm³/min (P=.218), and operative time was 75.1±26.6 vs 85.9±28.1 minutes (P=.077). Trilogy achieved a significantly higher SFR (88.4% vs 70%, P=.038). Complication rates were low (2.3% Trilogy vs 10% laser, P=.142). Residual stone volume did not differ significantly between groups.

CONCLUSION

Trilogy lithotripsy resulted in higher SFR without increasing operative time or complications, supporting its use as an effective alternative to high-power laser lithotripsy in Mini-PCNL, especially where active suction is unavailable.

Small tools, big impact and redefining endourology: the paradigm shift of ureteroscopy for large stones and percutaneous nephrolithotomy for small stones - a literature review

PURPOSE OF REVIEW

We aim to review the evolving paradigm in endourology, where technology has led us to manage small stones with ureteroscopy (URS) and large stones with miniaturized percutaneous nephrolithotomy (mPCNL) techniques. We analyse recent literature, their findings, emerging trends and newer technologies that are helping redefine modern day endourology in pushing these boundaries.

RECENT FINDINGS

A significant trend is the use of smaller devices to treat larger stones via ureteroscopy, and to treat smaller stones via percutaneous nephrolithotomy (PCNL). Improved laser technologies, smaller single use ureteroscopes and nephroscopes, suction access sheaths, all play a key role in this.The use of suction sheaths and vacuum assisted devices allows to control intrarenal pressure and help in reducing infectious and other complications whilst improving the stone-free rate (SFR). The treatment choice often depends on surgical expertise and available resources, guided by anatomical factors, stone composition and patient-specific considerations.

SUMMARY

The management of kidney stone disease has undergone a paradigm shift. While ureteroscopy is being done for larger renal stones, miniaturised PCNL is being done for small stones. This has been driven by a surge in technology, but a tailored and patient-centred approach is needed, and must be helped by guidelines and a multidisciplinary approach.

Percutaneous Nephrolithotomy in the Management of Renal Stone: An Audit of Outcomes and Complications

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is considered one of the most significant advances in minimally invasive urologic surgery. It offers a better stone-free rate compared to other available treatment modalities of renal stones at a lower complication rate compared to open surgery. Despite the availability of extracorporeal shock wave lithotripsy and flexible ureteroscopy, PCNL remains the gold standard modality for large and complex renal stones. Here, we review our initial experience with standard PCNL in the prone position for renal stones >1.5 cm with respect to stone clearance rate and complications as seen in our patients.

PATIENTS AND METHODS

Records of 24 patients who had standard PCNL and pneumatic lithotripsy between September 2020 and September 2023 were reviewed retrospectively. All the patients who had the standard PCNL for renal stones >1.5 cm were the subjects of this study. Data on patients' demographics, indication for the surgery, location of stone, size of stone, postoperative nephrostomy placement, nephrostomy tract size, complications, duration of surgery, duration of hospital stay, and status of stone clearance were obtained, and the data were subjected to statistical analysis.

RESULTS

A total of 24 patients underwent the standard PCNL. The mean age of the patients was 47.0 ± 10.28 years (16 males and 8 females; range: 17-68 years). Flank pain was the main indication for the surgery. The mean stone size was 2.5 cm (range: 1.6-3.3 cm). The mean Hounsfield unit was 1248.2 HU (range: 927-1502HU). At a single session, we achieved 100% stone clearance in 20 (83.3%) patients. Two (8.3%) of our patients required a second session of PCNL due to intraoperative bleeding and perforation of the pelvicalyceal system necessitating termination of the procedure and insertion of nephrostomy tube. In another 2 (8.3%) patients, the stones migrated and became inaccessible. One (4.2%) patient stayed for 10 days due to persistent urine leak, which eventually stopped after the insertion of a double-J stent and administration of antibiotics. The Clavien-Dindo grading system was used to classify postoperative complications. A total of 14 (58.3%) patients had Grade I complications, while 3 (12.5%) patients had Grade II and 1 (4.2%) had Grade IIIa complications.

CONCLUSION

PCNL is an effective minimally invasive technique for the treatment of large renal stones. Our initial experience suggests that the complication rate in PCNL is well within the acceptable limit.

Endourological Management of Renal Stones: A Systematic Review, Bayesian Network Meta-analysis and Meta-regression

OBJECTIVE

To compare stone-free rates (SFRs), operative times, and transfusion rates of various endoscopic techniques for kidney stone management.

METHODS

A systematic review was performed, identifying studies comparing the different endoscopic techniques in patients with renal stones. Studies were grouped by location and size of stones (lower pole, 1-2cm, and >2 cm). Data were extracted to build a Bayesian network modeling the comparisons. Meta-regression adjusted for variations in stone-free definitions. Odds ratios (OR) with 95% credible intervals were reported.

RESULTS

A total of 40 studies were included for analysis, providing a total population of 6696 patients. For lower pole stones, both percutaneous nephrolithotomy (PCNL) (OR 2.0 [1.2, 3.3]) and mini-PCNL (OR 2.3 [1.5, 3.6]) showed increased SFRs when compared to retrograde intrarenal surgery (RIRS), while micro-PCNL exhibited a non-significant difference (OR 0.94 [0.39,2.3]). For stones between 1-2cm, mini-PCNL showed an increased SFR (OR 2.5 [1.5,4.1]) when compared to RIRS; however, there was no significant difference in SFR among the rest of the interventions when compared to RIRS. For stones larger than 2 cm, PCNL, mini-PCNL, and ultramini-PCNL resulted in higher SFRs compared to RIRS.

CONCLUSION

For 1-2cm upper pole/interpolar stones, percutaneous approaches except mini-PCNL did not achieve superior SFRs compared to RIRS. For >2 cm stones and lower pole stones, all percutaneous methods, except micro-PCNL, exhibited higher stone clearance than RIRS.

Comparison of Trifecta Outcomes in Standard Versus Mini Percutaneous Nephrolithotomy for Renal Stone Management

INTRODUCTION

Urolithiasis is a common urological condition, and percutaneous nephrolithotomy (PCNL) is a widely used treatment option for renal stones. The trifecta analysis, which includes the complete stone-free rate (SFR), absence of complications (Clavien-Dindo classification), and no need for auxiliary procedures, provides a standardized method for comparing outcomes. This study evaluates the trifecta outcomes of standard PCNL versus mini PCNL Methodology: This prospective cohort study was conducted at the Department of Urology, Institute of Kidney Diseases, Peshawar, from January 2022 to March 2024. A total of 180 consecutive patients who underwent PCNL were enrolled in the study. Using a lottery method, patients were randomly assigned to two equal groups (standard PCNL and mini PCNL). Both groups consisted of 90 patients each. Patients who required a change in the planned surgical procedure were replaced with new participants from the sample frame. A structured proforma was used to record preoperative, perioperative, and postoperative data for the trifecta analysis. Data were analyzed using IBM SPSS Statistics for Windows, Version 23.0 (Released 2015; IBM Corp., Armonk, NY, United States). Logistic regression was performed to assess predictive factors for the trifecta, and the odds ratio (OR), confidence interval (CI), and p-value were calculated.

RESULTS

The mean age in the standard PCNL group was 43.21 ± 3.51 years vs 44.03 ± 3.17 years in the mini PCNL group (p = 0.10). The mean stone size in the standard PCNL group was 30.62 ± 5.88 mm vs 30.28 ± 6.03 mm in the mini PCNL group (p = 0.70). The mean stone density in the standard PCNL group was 1366.25 ± 74.28 HU vs 1342.66 ± 107.34 HU in the mini PCNL group (p = 0.08). Stones were completely cleared in 84 (93.3%) patients in the standard PCNL group and 69 (76.7%) in the mini PCNL group (p = 0.02). Auxiliary procedures, including extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), and repeat double J (DJ) stenting, were required in four patients (4.4%) in the standard PCNL group compared to 20 patients (20%) in the mini PCNL group. Regarding complications, the standard PCNL group recorded complications in 16 patients (17.77%), including Grade 1 (six patients), Grade 2 (five patients), and Grade 3 (five patients), according to the Clavein-Dindo classification. In the mini PCNL group, six patients (6.66%) experienced postoperative complications, including Grade 1 (five patients) and Grade 2 (one patient) (p = 0.02). The overall trifecta success rate was 71.12% in the standard PCNL group vs 50.03% in the mini PCNL group.

CONCLUSION

The trifecta analysis indicates that standard PCNL has a higher SFR, while mini PCNL is safer but requires more auxiliary procedures.

A Randomized Study Comparing Mini PCNL and RIRS for Renal Stones between 8 mm and 15 mm - A Single Institutional Experience

BACKGROUND

Renal stone disease presents a persistent challenge in urology, necessitating advancements in minimally invasive techniques for enhanced patient outcomes. Retrograde intrarenal surgery (RIRS) and mini percutaneous nephrolithotomy (mPCNL) have emerged as contemporary modalities to address intermediate-sized renal stones (8-15 mm) with precision and reduced invasiveness.

AIMS

To provide a comparative analysis of RIRS and mini PCNL in managing intermediate sized renal stones. To evaluate stone clearance rates, operative metrics, complications, and patient reported outcomes was integral to identifying optimal treatment strategies.

METHODS

Participants randomized to RIRS or mPCNL groups, with stone clearance rate as the primary outcome. Secondary measures included operative time, complication profiles, pain management, and the need for additional procedures.

RESULTS

The demographic data were comparable in our study. The stone size was 11.282 ± 1.7996 mm in mPCNL group and 11.248 ± 2.0340 mm in RIRS group. The fluoroscopy time was 49.40 ± 2.515 s in the RIRS group and 77.28 ± 2.466 s in the mPCNL group. There was a statistically significant variance in the operative time. After a month, the stone-free rates were 96% and 90% in the mPCNL and RIRS groups, respectively.

CONCLUSION

Our study emphasizes the importance of tailored treatment approaches based on patient characteristics. The overall operative time is higher in RIRS group, while the fluoroscopy time, complications, hemoglobin fall, and mean duration of hospital stay are higher in PCNL group. However, the stone clearance rates in both procedures have been remarkable. It is prudent to leave it to the discretion of the operating surgeon to choose the appropriate procedure for a given patient considering the variables.

Standard v mini percutaneous nephrolithotomy in the supine modified lithotomy position: a randomized pilot study on 10-25 mm stones

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is the recommended treatment for stones >2 cm in size. The majority of PCNL are still conducted with larger telescopes using tracts up to 30F in size. We have conducted a randomized pilot study comparing mini PCNL with our standard 22F PCNL for renal stones between 10 and 25 mm in diameter.

METHODS

Patients were randomized to either PCNL (24F Amplatz sheath/22F nephrosocope) or mini PCNL (18F Amplatz sheath/11F nephroscope). All operations were performed in the modified supine position. Patients were reviewed with imaging to assess stone clearance and complications.

RESULTS

Eighteen well matched patients were randomized. All procedures were completed as planned and all were tubeless with no complications. There were no differences in operative time, analgesia requirements or length of stay. Seven of nine (77.75%) standard PCNL were completely stone free at CT review with a 2 mm and a 5 mm fragments in the other patients. Four (44.4%) of the mini PCNL group were stone free, with stone fragments 4-10 mm remaining in the others. 40 patients/arm would be required for an adequately powered study.

CONCLUSION

There was no advantage in using mini PCNL compared to our standard 24F PCNL in this pilot study. There may be benefits in using mini PCNL compared to the more widely used 30F PCNL and it may be a more cost-effective alternative to laser pyeloscopic stone procedures.

Randomized control trial to compare mini-PCNL vs standard-PCNL for treatment of 1-2 cm size inferior calyceal renal stone

Background

Lower calyceal anatomy makes the stone clearance a difficult task across all treatment formats. Improvement in optics and miniaturization of instruments have offered an effective and safer alternative to percutaneous nephrolithotomy (PCNL). The study was conducted to compare the efficacy and complications associated with mini-PCNL vs standard-PCNL.

Methods

The study was a randomized control trial to compare mini-PCNL vs standard-PCNL for treatment of 1 to 2 cm inferior calyceal stones. Objectives were to compare peri-operative bleeding, operative-time, post-op analgesia requirement, hospital-stay and stone-free rate at 1 month. Patients with 1-2 cm inferior calyceal stones were included. Morbidly obese individuals, patients with renal malformation and paediatric age group were excluded.

Result

One hundred and fifty seven patients were included out of 207 who underwent PCNL in this period. 80 underwent mini-PCNL and 77 standard-PCNL. Mini-PCNL scored over standard in hospital-stay (3.96 vs 4.73 days), post-operative analgesia requirement (2.58 vs 5.55 gms) and drop in Hb (0.59 vs 0.81 gm/dl). Even stone clearance rate was better for mini-PCNL (87.01% vs 93.75%). Mean surgery time was marginally better for standard-PCNL (44.03 vs 43.33 mins). Stone clearance rate and average surgery time were comparable with no statistically significant difference in the two groups. Analgesia requirement was statistically lower in mini-PCNL due to smaller tract and tubeless-PCNL. Hospital stay was statistically lower in mini-PCNL due to lesser post-operative pain. Peri-operative bleeding was statistically lower in mini-PCNL due to smaller track dilatation and lesser tract bleeding.

Conclusions

Mini-PCNL is a safe and effective treatment option in the management of 1-2 cm inferior calyceal stones with significantly less bleeding, shorter hospital-stay and analgesia requirement as compared to standard-PCNL with comparable stone clearance rates.

International Alliance of Urolithiasis (IAU) consensus on miniaturized percutaneous nephrolithotomy

Over the past three decades, there has been increasing interest in miniaturized percutaneous nephrolithotomy (mPCNL) techniques featuring smaller tracts as they offer potential solutions to mitigate complications associated with standard PCNL (sPCNL). However, despite this growing acceptance and recognition of its benefits, unresolved controversies and acknowledged limitations continue to impede widespread adoption due to a lack of consensus on optimal perioperative management strategies and procedural tips and tricks. In response to these challenges, an international panel comprising experts from the International Alliance of Urolithiasis (IAU) took on the task of compiling an expert consensus document on mPCNL procedures aimed at providing urologists with a comprehensive clinical framework for practice. This endeavor involved conducting a systematic literature review to identify research gaps (RGs), which formed the foundation for developing a structured questionnaire survey. Subsequently, a two-round modified Delphi survey was implemented, culminating in a group meeting to generate final evidence-based comments. All 64 experts completed the second-round survey, resulting in a response rate of 100.0%. Fifty-eight key questions were raised focusing on mPCNLs within 4 main domains, including general information (13 questions), preoperative work-up (13 questions), procedural tips and tricks (19 questions), and postoperative evaluation and follow-up (13 questions). Additionally, 9 questions evaluated the experts' experience with PCNLs. Consensus was reached on 30 questions after the second-round survey, while professional statements for the remaining 28 key questions were provided after discussion in an online panel meeting. mPCNL, characterized by a tract smaller than 18 Fr and an innovative lithotripsy technique, has firmly established itself as a viable and effective approach for managing upper urinary tract stones in both adults and pediatrics. It offers several advantages over sPCNL including reduced bleeding, fewer requirements for nephrostomy tubes, decreased pain, and shorter hospital stays. The series of detailed techniques presented here serve as a comprehensive guide for urologists, aiming to improve their procedural understanding and optimize patient outcomes.

Comparison of CROES, Guy's, S.T.O.N.E., and S-ReSC nephrolithometric scoring systems in predicting success and complications in patients undergoing supine mini percutaneous nephrolithotomy

In addition to the fact that the significance of the nephrolitometric scoring systems (NSSs) remains unclear, no study has been conducted to assess the effectiveness of these scoring systems in percutaneous nephrolithotomy (PNL) performed in the supine position. We aimed to compare the CROES, Guy's scoring system (GSS), S.T.O.N.E., and S-ReSC NSSs for success and complications in patients undergoing supine mini-PNL (m-PNL). The prospectively recorded data of the patients who underwent supine m-PNL was reviewed retrospectively, and a total of 112 patients were included in the study. Demographic, operation, post-procedure data, and CROES, GSS, S.T.O.N.E., and S-ReSC scores were assessed and compared between the stone-free (SF) and residuel groups. There were significant differences between the SF and residual groups in terms of mean CROES, S.T.O.N.E., and S-ReSC scores (p = 0.003, p = 0.009, and p = 0.015, respectively). Similarly, there were significant differences between the grades of these scoring systems and the success of the procedure (p = 0.035, p = 0.007, and p = 0.007, respectively). However, the GSS was insignificant. The area under curve values in ROC analysis of CROES, S.T.O.N.E., and S-ReSC NSSs were 0.695, 0.665, and 0.656, respectively (p = 0.003, p = 0.011, and p = 0.017, respectively). No statistically significant difference was found between the grades of all four NSSs and the complication rates. The study showed a strong correlation between CROES, STONE, and S-ReSC NSSs in predicting SF status after supine m-PNL. However, none of the NSSs could predict the complications.

Clinical efficacy of mini-percutaneous nephrolithotomy versus retrograde intrarenal surgery for the management of upper urinary tract calculus (1-2.5 cm) in children ≤10 years of age

BACKGROUND

With improvements in endoscopic surgery, open surgical procedures for urinary system stones have cleared the path for the use of less invasive treatment modalities in patients with pediatric kidney stone disease. Extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), and retrograde intrarenal surgery (RIRS) are among the treatment options available.

OBJECTIVE

To prospectively evaluate the outcomes of mini-percutaneous nephrolithotomy and retrograde intrarenal surgery (RIRS) for children ≤10 years of age with upper urinary tract calculus (1-2.5 cm).

STUDY DESIGN

Sixty pediatric patients with single or multiple renal stones (1-2.5 cm in diameter) were collected prospectively and equally divided into two groups to undergo RIRS or mini-PCNL. The operative and postoperative outcomes of both groups were analyzed.

RESULTS

The groups' mean ages and genders were comparable. The mean stone size for the RIRS group was 1.86 cm and 1.69 cm for the PCNL group (P = 0.449). The PCNL group had statistically longer mean fluoroscopy and hospitalization times. The stone-free rates (SFRs) after a single procedure were 27 (90%) in the PCNL group and 25 (83.33%) in the RIRS group (P = 0.706). The UAS was placed in 13 (43.33%) patients in the RIRS group. In the RIRS group, 14 (46.67%) children required preoperative DJ stent application to passively dilate the ureteric orifice. As regard post DJ stenting, 13 (46%) cases applied DJ in the mini PCNL group. major complications were observed in either group. Minor complication (Clavien 1-3) rates were 16.66% and 13.33% for the PCNL and RIRS groups, respectively. There were no differences found between the RIRS and mini-PCNL groups regarding operative time. The mean cost of RIRS was $703.96 and $537.03 for the mini-PCNL.

CONCLUSION

According to the results of this study, mini-PCNL and RIRS are effective procedures for treating renal stones in children up to 2.5 cm with comparable success and complication rates. Hospital stay, radiation exposure, and fluoroscopy time are significantly lower in RIRS than in the mini PCNL technique. Although RIRS is effective, a major disadvantage is the greater requirement for JJ stent insertion either before or after the procedure and the consequent need for a second procedure for removal.

Management of urinary stones: state of the art and future perspectives by experts in stone disease

AIM

To present state of the art on the management of urinary stones from a panel of globally recognized urolithiasis experts who met during the Experts in Stone Disease Congress in Valencia in January 2024. Options of treatment: The surgical treatment modalities of renal and ureteral stones are well defined by the guidelines of international societies, although for some index cases more alternative options are possible. For 1.5 cm renal stones, both m-PCNL and RIRS have proven to be valid treatment alternatives with comparable stone-free rates. The m-PCNL has proven to be more cost effective and requires a shorter operative time, while the RIRS has demonstrated lower morbidity in terms of blood loss and shorter recovery times. SWL has proven to be less effective at least for lower calyceal stones but has the highest safety profile. For a 6mm obstructing stone of the pelviureteric junction (PUJ) stone, SWL should be the first choice for a stone less than 1 cm, due to less invasiveness and lower risk of complications although it has a lower stone free-rate. RIRS has advantages in certain conditions such as anticoagulant treatment, obesity, or body deformity. Technical issues of the surgical procedures for stone removal: In patients receiving antithrombotic therapy, SWL, PCN and open surgery are at elevated risk of hemorrhage or perinephric hematoma. URS, is associated with less morbidity in these cases. An individualized combined evaluation of risks of bleeding and thromboembolism should determine the perioperative thromboprophylactic strategy. Pre-interventional urine culture and antibiotic therapy are mandatory although UTI treatment is becoming more challenging due to increasing resistance to routinely applied antibiotics. The use of an intrarenal urine culture and stone culture is recommended to adapt antibiotic therapy in case of postoperative infectious complications. Measurements of temperature and pressure during RIRS are vital for ensuring patient safety and optimizing surgical outcomes although techniques of measurements and methods for data analysis are still to be refined. Ureteral stents were improved by the development of new biomaterials, new coatings, and new stent designs. Topics of current research are the development of drug eluting and bioresorbable stents. Complications of endoscopic treatment: PCNL is considered the most invasive surgical option. Fever and sepsis were observed in 11 and 0.5% and need for transfusion and embolization for bleeding in 7 and 0.4%. Major complications, as colonic, splenic, liver, gall bladder and bowel injuries are quite rare but are associated with significant morbidity. Ureteroscopy causes less complications, although some of them can be severe. They depend on high pressure in the urinary tract (sepsis or renal bleeding) or application of excessive force to the urinary tract (ureteral avulsion or stricture). Diagnostic work up:  Genetic testing consents the diagnosis of monogenetic conditions causing stones. It should be carried out in children and in selected adults. In adults, monogenetic diseases can be diagnosed by systematic genetic testing in no more than 4%, when cystinuria, APRT deficiency, and xanthinuria are excluded. A reliable stone analysis by infrared spectroscopy or X-ray diffraction is mandatory and should be associated to examination of the stone under a stereomicroscope. The analysis of digital images of stones by deep convolutional neural networks in dry laboratory or during endoscopic examination could allow the classification of stones based on their color and texture. Scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) is another fundamental research tool for the study of kidney stones. The combination of metagenomic analysis using Next Generation Sequencing (NGS) techniques and the enhanced quantitative urine culture (EQUC) protocol can be used to evaluate the urobiome of renal stone formers. Twenty-four hour urine analysis has a place during patient evaluation together with repeated measurements of urinary pH with a digital pH meter. Urinary supersaturation is the most comprehensive physicochemical risk factor employed in urolithiasis research. Urinary macromolecules can act as both promoters or inhibitors of stone formation depending on the chemical composition of urine in which they are operating. At the moment, there are no clinical applications of macromolecules in stone management or prophylaxis. Patients should be evaluated for the association with systemic pathologies.

PROPHYLAXIS

Personalized medicine and public health interventions are complementary to prevent stone recurrence. Personalized medicine addresses a small part of stone patients with a high risk of recurrence and systemic complications requiring specific dietary and pharmacological treatment to prevent stone recurrence and complications of associated systemic diseases. The more numerous subjects who form one or a few stones during their entire lifespan should be treated by modifications of diet and lifestyle. Primary prevention by public health interventions is advisable to reduce prevalence of stones in the general population. Renal stone formers at "high-risk" for recurrence need early diagnosis to start specific treatment. Stone analysis allows the identification of most "high-risk" patients forming non-calcium stones: infection stones (struvite), uric acid and urates, cystine and other rare stones (dihydroxyadenine, xanthine). Patients at "high-risk" forming calcium stones require a more difficult diagnosis by clinical and laboratory evaluation. Particularly, patients with cystinuria and primary hyperoxaluria should be actively searched.

FUTURE RESEARCH

Application of Artificial Intelligence are promising for automated identification of ureteral stones on CT imaging, prediction of stone composition and 24-hour urinary risk factors by demographics and clinical parameters, assessment of stone composition by evaluation of endoscopic images and prediction of outcomes of stone treatments. The synergy between urologists, nephrologists, and scientists in basic kidney stone research will enhance the depth and breadth of investigations, leading to a more comprehensive understanding of kidney stone formation.

Percutaneous Nephrolithotomy for De Novo Urolithiasis After Kidney Transplantation: A Systematic Review of the Literature

Introduction and Objective: Renal transplantation is the treatment for end-stage renal disease that offers better quality of life and survival. Among the possible complications that might affect allografts, urolithiasis might have severe consequences, causing acute kidney injury (AKI) or septic events in immunocompromised patients. Allograft stones might be treated with percutaneous nephrolithotomy (PCNL). The aim of this Cochrane style review was to assess the safety and efficacy of PCNL in patients with renal transplant. Methods: A comprehensive search in the literature was performed including articles between July 1982 and June 2023, with only English original articles selected for this review. Results: The final review encompassed nine articles (108 patients). The mean age was 46.4 ± 8.7 years, with a male:female ratio of 54:44. The average time from transplantation to urolithiasis onset was 47.54 ± 23.9 months. Predominant symptoms upon presentation were AKI (32.3%), followed by urinary tract infection and fever (24.2%), and oliguria (12.9%). The mean stone size was 20.1 ± 7.3 mm, with stones located in the calices or pelvis (41%), ureteropelvic junction (23.1%), or proximal ureter (28.2%). PCNL (22F-30F) was more frequently performed than mini-PCNLs (16F-20F) (52.4% vs 47.6%). Puncture was guided by ultrasound (42.9%), fluoroscopy (14.3%), or both (42.9%). The stone-free rate (SFR) and complication rates were 92.95% (range: 77%-100%) and 5.5%, respectively, with only one major complication reported. Postoperatively, a ureteral stent and nephrostomy were commonly placed in 47%, with four patients needing a second look PCNL. During an average follow-up of 32.5 months, the recurrence rate was 3.7% (4/108), and the mean creatinine level was 1.37 ± 0.28 mg/dL. Conclusions: PCNL remains a safe and effective option in de novo allograft urolithiasis, allowing to treat large stones in one-step surgery. A good SFR is achieved with a low risk of minor complications. These patients should be treated in an endourology center in conjunction with the renal or transplant team.

Comparison of supine-prone percutaneous nephrolithotomy methods in the treatment of kidney stones in pediatric patients: prospective randomized study

Mini-PCNL is one of the most effective surgical methods in the treatment of kidney stones in pediatric patients. In this study, we aimed to compare PCNL in the supine-prone position in pediatric patients (especially operation time, postop complications, hospital stay and stone-free rates).We conducted our study in a randomized and prospective manner. Patients with lower pole stones larger than 1 cm, stones larger than 1.5 cm in the pelvis, upper pole, midpole or multiple locations, and patients who did not respond to ESWL or whose family that preferred mini-PCNL to be the primary treatment were included in the study. Patients with any previous kidney stone surgery, patients with coagulation disorders and patients with retrorenal colon were excluded from the study. Between 2021 and 2023, a total of 144 patients underwent PCNL. 68 of these patients had supine PCNL and 76 prone PCNL. Postoperative Clavien grade1 complication occurred in a total of 7 patients in the prone position; Clavien grade1 complication occurred in 1 patient in the supine position. The mean operation time for prone PCNL was 119.88 ± 28.32 min, and the mean operative time for supine PCNL was 98.12 ± 14.97 the mean hospitalization time in prone PCNL was 3.56 ± 1.12 days, and 3.00 ± 0.85 days in supine PCNL. In conclusion, supine PCNL is a safe and effective method in the treatment of pediatric kidney stones and postoperative complications were observed to be less; the operation time and hospital stay were shorter in supine PCNL.

Assessment of Effectiveness and Safety of Aspiration-Assisted Nephrostomic Access Sheaths in PCNL and Intrarenal Pressures Evaluation: A Systematic Review of the Literature

Background: Different suction-assisted nephrostomic sheaths have been developed for percutaneous nephrolithotomy (PCNL). Objectives: (1) To examine PCNL techniques performed with different aspiration-assisted sheaths (Clear Petra® sheath, Superperc, SuperminiPCNL, and a miniPCNL patented sheath), with specific regard to effectiveness and safety outcomes in adult and paediatric patients; (2) to extrapolate intrarenal pressure (IRP) data during these procedures. Methods: A systematic literature search was performed in accordance with PRISMA guidelines. Relevant articles up to 8 February 2024 were included. Results: Twenty-five studies were selected, thirteen retrospective and twelve prospective. The use of four different aspirating sheaths for miniPCNL was reported: Clear Petra® sheath, Superperc, SuperminiPCNL, and a miniPCNL patented sheath. Stone free rates (SFRs) across techniques ranged from 71.3% to 100%, and complication rates from 1.5% to 38.9%. Infectious complication rates varied from 0 to 27.8% and bleeding complication rates from 0 to 8.9%. Most complications were low grade ones. The trend among studies comparing aspiration- and non-aspiration-assisted miniPCNL was towards equivalent or better SFRs and lower overall infectious and bleeding complication rates in suction techniques. Operation time was consistently lower in suction procedures, with a mean shortening of the procedural time of 19 min. Seven studies reported IRP values during suction miniPCNL. Two studies reported satisfactory SFRs and adequate safety profiles in paediatric patient cohorts. Conclusions: MiniPCNL with aspirating sheaths appears to be safe and effective in both adult and paediatric patients. A trend towards a reduction of overall infectious and bleeding complications with respect to non-suction procedures is evident, with comparable or better SFRs and consistently shorter operative times. The IRP profile seems to be safe with the aid of aspirating sheaths. However, high quality evidence on this topic is still lacking.

Comparison of lithotripsy methods during mini-PNL: is there a role for ballistic lithotripsy in the era of high-power lasers

BACKGROUND

For renal stones > 20 mm, percutaneous nephrolithotomy (PNL) offers the best stone clearance rates with acceptable complication rates. This study aimed to compare the efficiency of high-power holmium YAG laser and ballistic lithotripsy during mini-PNL.

METHODS

Data from 880 patients who underwent mini-PNL for renal stones was investigated retrospectively. The study utilized propensity score matching to create two groups: laser lithotripsy (n = 440) and ballistic lithotripsy (n = 440). The groups were matched based on stone size, Guy's stone score, and stone density. The main objectives of the study were to assess the stone-free rate (SFR), duration of surgery, and complication rates.

RESULTS

The average age of the population was 51.4 ± 7.1 years, with a mean stone size of 28.6 ± 8.3 mm and a mean stone density of 1205 ± 159 HU. There were no significant differences between the groups. The SFRs of the laser lithotripsy and ballistic lithotripsy were 92.5% and 90.2%, respectively (p = 0.23). The laser lithotripsy group had a notably shorter surgery time (40.1 ± 6.3 min) compared to the ballistic lithotripsy group (55.6 ± 9.9 min) (p = 0.03). Complication rates were similar (p = 0.67).

CONCLUSIONS

Our study shows that a high-power holmium YAG laser provides quicker operation time compared to ballistic lithotripsy. However, ballistic lithotripsy is still an effective and safe option for stone fragmentation during mini-PNL. In places where a high-power holmium YAG laser is not available, ballistic lithotripters are still a safe, effective, and affordable option for mini-PNL.

Mini-percutaneous nephrolithotomy: Is smaller better for kidney stones in patients with neurogenic bladder?

INTRODUCTION

Patients with neurologic bladder are at an increased risk for urolithiasis, and currently, data on mini-percutaneous nephrolithotomy in this population are limited. Our objective was to compare mini (15F)-percutaneous nephrolithotomy, standard (24F)-PCNL and flexible ureteroscopy in terms of efficacy and safety in treatment of kidney stones in patients with neurogenic lower urinary tract dysfunction (NLUTD).

METHODS

We conducted a retrospective monocentric study in our neuro-urological referral centre. All consecutive patients with NLUTD and a cumulative size of renal calculi greater than 15mm or 10mm in the lower calyx, who had extraction surgery between 2005 and 2020, were included. The primary endpoint was the one-session stone-free rate (SFR) at 3 months on a CT scan. The secondary endpoints were complication (Clavien-Dindo grading system), operative time, blood loss and length of hospital stay.

RESULTS

We performed 76 standard PCNL (sPCNL), 46 flexible ureteroscopy lithotripsy (fURL) and 25 miniaturized PCNL (mPCNL). The one-session SFR was 37.5% for the mPCNL group, 38.2% for the sPCNL group and 37% for the fURL group with no significant difference between the three procedures (P=0.99). Early complications, blood loss and transfusion rates were lower in the mPCNL group than in the sPCNL group (P=0.047) and comparable to fURL group. The final SFRs after a second intervention for mPCNL, sPCNL and fURL were 48%, 61.8% and 63%, respectively (P=0.67).

CONCLUSION

The efficacy of mPCNL in patients with NLUTD was not different from other techniques, but a significantly lower rate of complications than sPCNL was observed.

LEVEL OF PROOF

3.

Miniaturizing the approach to upper tract renal calculi: Is smaller always better? A narrative review

Newer modalities for treating upper tract urinary stones focus on maintaining and improving outcomes, reducing complications, and optimizing patient care. This narrative review aims to outline novel miniaturized endourological innovations for managing upper tract calculi.

Comparison Between Mini-Percutaneous Nephrolithotomy and Standard Percutaneous Nephrolithotomy in Management of Large Renal Stones: A Randomized, Controlled Clinical Trial

Objectives: The aim of this study was to compare mini-percutaneous nephrolithotomy (PNL) and standard PNL in management of renal stones (20-40 mm) with regard to the operative time, fluoroscopy time, blood loss, stone-free rate, and postoperative complications. Subjects and Methods: This prospective, randomized comparative study was carried out on 93 patients divided into two groups: Group A included 44 patients who underwent standard PNL, whereas Group B included 49 patients who underwent mini-PNL. Results: Standard PNL showed shorter operative time, yet longer hospitalization and nephrostomy and catheterization time. The mean drop in hemoglobin level was significantly lower in the mini-PNL group. In the 1st postoperative week, the stone-free rate was higher in the standard PNL group, but this was statistically insignificant. However, 4 weeks postoperatively, the stone-free rate was significantly higher in Group A. Postoperative pain and the need for postoperative analgesia were significantly higher in standard PNL patients. Conclusions: Standard PNL achieved a higher stone-free rate and shorter operative time, while mini-PNL had the advantage of shorter hospitalization time and lower incidence of pain and postoperative complications.

Mini-versus standard percutaneous nephrolithotomy in pediatric population: A randomized controlled trial

INTRODUCTION

Mini PCNL has gained popularity in adult patients due to reduction in the complication rate with comparable stone free rate. There is paucity of level 1 evidence regarding the benefit of mini PCNL in the pediatric group.

OBJECTIVE

We performed a randomised study to compare mini PCNL (mPCNL) with standard PCNL (sPCNL) for the management of renal calculi in patients less than 18 years of age in terms of safety, efficacy, and stone-free rate (SFR).

MATERIALS AND METHODS

A randomised controlled trial was performed on 50 children who underwent PCNL from June 2015 to March 2021, who were divided into two groups. Group I had 25 patients managed with mPCNL (sheath size 16.5 Fr) and Group II had 25 patients who underwent sPCNL (sheath size 26 Fr). Primary outcomes including stone free rates (SFR) and hemoglobin drop and secondary outcomes like operative time, complications, pain score, need of analgesia, incidence of nephrostomy site leak, hospital stay in days were compared between the two groups.

RESULTS

The mean age of patients in groups I and II was 9.4 ± 2.6 and 10.4 ± 2.26 years, respectively (p = 0.15). The mean stone sizes in both groups I and II were 18.6 ± 2.56 and 20.2 ± 3.58 mm, respectively (p > 0.05). The stone free rate for group I was 88% and for group II, 92% (p = 0.64). The average drop in hemoglobin was higher in group II compared to group I (1.1 ± 0.31 g/dl and 1.7 ± 0.23 g/dl respectively; p < 0.0001), however the mean blood transfusion rate was not significantly different in both groups. The operating time was shorter in group II compared to group I (p-value - 0.0030). The pain scores were lesser for the group I. Grade I complications were higher in group II as compared to group I (p-0.047); however, grade II complications were comparable in both groups. The mean hospital stay was not significantly different in both groups.

DISCUSSION

This study confirms the role of mini PCNL in pediatric patients with renal stones. The stone clearance rate of mini PCNL is equivalent to standard PCNL, with lesser blood loss and postoperative complications, however with longer operative time during mPCNL. The small number of the participants in both arms is a limitation of this study and may also reflect fewer children with urolithiasis being treated surgically even in a tertiary care referral centre.

CONCLUSIONS

Mini-PCNL offers equivalent stone free outcome with lower complications rate compared to the standard PCNL for all types of renal stones.

What is the safe and effective dilator number during access in PCNL? Three-shot dilation versus classical sequential Amplatz dilation

BACKGROUND

Although PCNL has been used for a long time to treat nephrolithiasis, there is still contradictory information concerning the use of the dilation method. In this study, we aimed to compare conventional sequential Amplatz dilatation (SAD) using ten dilators and a method using three dilators (12, 20, and 30 Fr), which we named "three-shot dilatation" (3SD), in terms of fluoroscopy time (FT), operation time, bleeding and stone-free rates.

METHODS

The study included patients who underwent PCNL with the SAD and 3SD methods. A different surgeon with extensive endourology experience applied each technique. One of the surgeons operated on the patients using the SAD method with ten dilators, and the other surgeon performed the operations using the 3SD method involving three Amplatz dilators (12, 20, and 30 Fr).

RESULTS

A total of 283 patients, 138 in the 3SD group and 145 in the SAD group, were included in the study. The mean age of the patients was 47.32 ± 13.71 years. There was no statistically significant difference between the two groups regarding preoperative characteristics (p > 0.05). The FTs of access 2, total access, and total operation were significantly shorter in the 3SD group (p = 0.0001). The decrease in hemoglobin was statistically significant in the 3SD group compared to the SAD group (p = 0.022), while the blood transfusion requirements of the groups were similar (p = 0.176). There was no statistically significant difference between the two groups regarding stone-free rates (p = 0.973). In four patients in the SAD group, re-access was necessary due to the loss of passage due to the guide wire slipping out of its place.

CONCLUSION

Intraoperative FT can be shortened using the described 3SD method without compromising surgical safety. However, this method can be used as an intermediate step in the transition to one-shot dilation by surgeons experienced in performing SAD.

Which position is more advantageous for percutaneous nephrolithotomy: supine or prone?

Percutaneous nephrolithotomy (PNL) can be performed in a number of different positions. Our aim was to evaluate the convenience and advantages of the supine position following the transition from the prone to the supine position. 94 patients undergoing supine PNL (Group-1) and 93 patients undergoing prone PNL (Group-2) were retrospectively reviewed and included in the study. Patients who underwent mini-PNL (mPNL) were selected from Group-1 and Group-2 and divided into Group-1A supine mPNL patients (77) and Group-2A prone mPNL patients (53). Demographic characteristics, operative data and post-operative parameters were compared between these groups. The operation time was 74.4 ± 21.9 min in Group-1A and 79.2 ± 19.8 min in Group-2A (p = 0.076). The median value of fluoroscopy time was 30 s in Group-1A and 40 s in Group-2A (p = 0.003). In Group-1A, 59 patients had no intraoperative double-J stent (DJS) insertion and 18 patients had DJS insertion, while in Group-2A, 24 patients had no DJS insertion and 29 patients had DJS insertion (p < 0.001). MPNL was performed in 81.9% of patients in the supine position and 57% in the prone position. This difference was statistically significant (p < 0.001). No significant difference was found with regard to the success rate and the complications of mPNL. Fluoroscopy time is shorter in the supine position. Moreover, the insertion rates of DJS are low. With increasing experience, we have found that our standard PNL (sPNL) rate is gradually decreasing and more mPNL is being performed.

Concerns about stone free rate and procedure events of percutaneous nephrolithotripsy (PCNL) for 2-4 cm kidney stones by standard-PCNL vs mini-PCNL- comparative randomised study

BACKGROUND

To compare the efficacy and safety of standard percutaneous nephrolithotomy (PCNL) with mini- PCNL for kidney stones 2-4 cm.

METHODS

Eighty patients were enrolled in a comparative study, they were randomly divided into mini-PCNL group (n = 40) and standard-PCNL (n = 40). Demographic characteristics, perioperative events, complications, stone free rate (SFR) were reported.

RESULTS

Both groups showed no significant difference in clinical data about age, stone location, back pressure changes, and body mass index. The mean operative time was (95 ± 17.9 min) in mini-PCNL, and (72.1 ± 14.9 min). Stone free rate were 80% and 85% in mini-PCNL and standard-PCNL respectively. Intra-operative complications, post-operative need for analgesia, hospital stay were significantly higher in standard-PCNL compared to mini-PCNL (85% vs. 80%). The study followed CONSORT 2010 guidelines for reporting parallel group randomization.

CONCLUSION

Mini-PCNL is an effective and safe treatment of kidney stones 2-4 cm, it has the advantage over standard-PCNL being has less intra-operative events, less post-operative analgesia, shorter hospital stay, while operative time and stone free rate are comparable when considering multiplicity, hardness, and site of stones.

Ultrasound versus fluoroscopy as imaging guidance for percutaneous nephrolithotomy: A systematic review and meta-analysis

OBJECTIVES

To determine whether the outcomes of ultrasound-guided percutaneous nephrolithotomy (UG-PCNL), an alternative to traditional fluoroscopy-guided percutaneous nephrolithotomy (FG-PCNL), are comparable.

METHODS

A systematic search of PubMed, Embase, and the Cochrane Library was carried out to discover investigations comparing UG-PCNL to FG-PCNL, and accordingly, a meta-analysis of those studies was performed. The primary outcomes included the stone-free rate (SFR), overall complications based on Clavien-Dindo classification, duration of surgery, duration of patients' hospitalization, and hemoglobin (Hb) drop during the surgery. All statistical analyses and visualizations were implemented utilizing R software.

RESULTS

Nineteen studies, including eight randomized clinical trials (RCTs) and eleven observational cohorts, comprising 3016 patients (1521 UG-PCNL patients) and comparing UG-PCNL with FG-PCNL met the inclusion criteria of the current study. Considering SFR, overall complications, duration of surgery, duration of hospitalization, and Hb drop, our meta-analysis revealed no statistically significant difference between UG-PCNL and FG-PCNL patients, with p-values of 0.29, 0.47, 0.98, 0.28, and 0.42, respectively. Significant differences were discovered between UG-PCNL and FG-PCNL patients in terms of the length of time they were exposed to radiation (p-value< 0.0001). Moreover, FG-PCNL had shorter access time than UG-PCNL (p-value = 0.04).

CONCLUSION

UG-PCNL provides the advantage of requiring less radiation exposure while being just as efficient as FG-PCNL; thus, this study suggests prioritizing the use of UG-PCNL.

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

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Miniaturization in percutaneous nephrolithotomy: What is new?

Objective

To summarize recent advancements in mini-percutaneous nephrolithotomy (mini-PCNL) in surgical technique, stone removal strategy, lithotripsy, and surgical model from the current literature.

Methods

We conducted a narrative review of relevant English-language articles up to October 2022 using the PubMed and Web of Science databases. The following keywords were used in the search: "percutaneous nephrolithotomy", "minimally invasive percutaneous nephrolithotomy", "mini-PCNL", "mini-perc", "mPCNL", and "miniaturization".

Results

A series of new progress has been made in many aspects of mini-PCNL, such as further reduction of tract size-needle perc and further improvement of robotic-assisted PCNL-artificial intelligence-powered robotic devices.

Conclusion

Many studies and trials have been conducted to reduce morbidity and increase the safety and effectiveness of mini-PCNL. It is crucial to realize that miniaturization of PCNL requires not only a smaller percutaneous tract size, but also an adjustment strategically in renal access, stone removal, lithotripsy, and surgical model in general. More large-scale prospective research needs to be carried out to further validate and optimize the safety and effectiveness of mini-PCNL.

Reliability of nephrolithometric nomograms in patients treated with minimally invasive percutaneous nephrolithotomy: A precision study

Objectives

The study aimed to evaluate quality of nephrolithometric nomograms to predict stone-free rates (SFRs) and complication rates (CRs) in case of minimally invasive percutaneous nephrolithotomy (PNL). In the last decade, nomograms have been introduced to estimate the SFRs and CRs of PNL. However, no data are available regarding their reliability in case of utilization of miniaturized devices. Herein we present a prospective multicentric study to evaluate reliability of Guy's stone score (GSS), the stone size, tract length, obstruction, number of involved calyces, and essence of stone (S.T.O.N.E.) nephrolithometry score and Clinical Research Office of the Endourological Society (CROES) score in patients treated with minimally invasive PNL.

Methods

We evaluated SFRs and CRs of 222 adult patients treated with miniaturized PNL. Patients were considered stone-free if no residual fragments of any size at post-operative unenhanced computed tomography scan. Patients demographics, SFRs, and CRs were reported and analyzed. Performances of nomograms were evaluated with the area under the curve (AUC).

Results

We included 222 patients, the AUCs of GSS, CROES score, and S.T.O.N.E. nephrolithometry score were 0.69 (95% confidence interval [CI] 0.61-0.78), 0.64 (95% CI 0.56-0.73), and 0.62 (95% CI 0.52-0.71), respectively. Regarding SFRs, at multivariate binomial logistic regression, only the GSS had significance with an odds ratio of 0.53 (95% CI 0.31-0.95, p=0.04). We did not find significant correlation with complications, with only a trend for GSS.

Conclusion

This is the first study evaluating nomograms in miniaturized PNL. They still show good reliability; however, our data showed lower performances compared to standard PNL. We emphasize the need of further studies to confirm this trend. A dedicated nomogram for minimally invasive PNL may be necessary.

Super-Mini Percutaneous Nephrolithotomy for Nephrolithiasis: A Systematic Review and Meta-Analysis

We aimed to conduct a systematic review and meta-analysis to summarize the current evidence regarding the role of super-mini percutaneous nephrolithotomy (SMP), which refers to a 7-Fr nephroscope placed through a tract sized 10-14 Fr, in treating renal stones and compare its outcomes with the standard mini-percutaneous nephrolithotomy (PCNL) techniques. A systematic literature search was conducted on the Medline database via PubMed and SCOPUS until May 2022 to retrieve the relevant studies. The titles and abstracts of unique records were screened for eligibility, followed by the full-text screening of potentially eligible abstracts. Data extraction was performed by two independent reviewers. The risk of bias assessment was conducted based on the study design. Open Meta (Analyst) and Review Manager 5.4 were used to perform all analyses. A total of 14 studies (n = 4,323 patients) were included, with two randomized controlled trials, one single-arm trial, and 11 cohort studies. The stone-free rate (SFR) of SMP was 91.4%. The pooled analysis showed no significant difference between SFR in mini-PCNL (mean difference (MD) = 1.03, 95% confidence interval (CI) = (0.99, 1.06), p = 0.12) and flexible ureteroscopy (MD = 0.84, 95% CI = (0.4, 1.76), p = 0.65]. On the other hand, SMP had a better SFR rate when compared with retrograde intrarenal surgery (MD = 1.3, 95% CI = (1.01, 1.66), p = 0.04). The pooled mean operative time of SMP was 49.44 minutes (95% CI = (41, 57.88), p < 0.001), which was longer than mini-PCNL (MD = 1.92, p < 0.001) and shorter than ureteroscopy (MD = -17.17, p < 0.00001). In the SMP group, the postoperative complications included fever (>38°C), pain, and hematuria, with an incidence of 7.6%, 2.3%, and 3.4%, respectively. The mean length of hospital stay after SMP was 2.4 days (95% CI = (2.17, 2.7), p < 0.001). The current evidence suggests that SMP is a safe and effective technique in the management of renal stones in both children and adults.

MINIMALLY INVASIVE PERCUTANEOUS NEPHROLITHOTRYPSY IN THE TREATMENT OF PATIENTS WITH KIDNEY STONES

OBJECTIVE

The aim: To evaluate the outcomes and complications rate of minipercutaneous nephrolithotripsy (MPCNL) for renal stones treatment.

PATIENTS AND METHODS

Materials and methods: MPCNL was performed to 123 patients with kidney stones from January 2020 till November 2021. All operations were performed under endotracheal inhalation anesthesia. After the ureteral catheter was introduced ultrasound controlled punction of kidney collecting system and work channel dilation were performed. Stones were fragmented by holmium laser. The fragments extracted passively with fluid flow through the outer sheath. Operation ended by introduction of nephrostomy tube 14Ch.

RESULTS

Results: In total 135 MPCNLs were performed in 123 patients. The average duration of operations was 55±5,4 minutes and stone size was 1,6±0,2 sm. 12 patients were per¬formed simultaneous MPCNL on both sides. The simultaneous MPCNL duration amounted 105±8,1 min. In 3 (2,2%) cases residual stones were observed. The average hospital stay was 1,31±0,2 days. The renal drainage was removed in 24 ± 3,2 hours after operation. Acute pyelonephritis was presented in 4 (3,3%) and postoperative bleeding in 2 (1,6%) patients, which were stopped by antibacterial and hemostatic drugs with drainage occlusion respectively.

CONCLUSION

Conclusions: To advantages of MPCNL belong short hospital stay, high safety level, insignificant intraoperative and postoperative bleeding, good operation field visualization, opportunity of quick removal of renal drainage, ureteral and urethral catheters. Benefit in patients with severe comorbidities, opportunity of simultaneous bilateral MPCNL and almost complete postoperative pain absence allow to consider MPCNL the operation of choice in kidney stone management.

Mini Versus Standard Percutaneous Nephrolithotomy for the Management of Renal Stone Disease: Systematic Review and Meta-analysis of Randomized Controlled Trials

CONTEXT

Mini percutaneous nephrolithotomy (mPNL) involves the creation of a smaller access tract compared with standard PNL (sPNL). Smaller tract sizes could lead to decreased blood loss, pain, and need for blood transfusion. Previous studies on this topic have reported variable findings and were of poor quality.

OBJECTIVE

To compare the safety and efficacy of mPNL with those of sPNL for the management of patients with renal stone disease by conducting a systematic review and meta-analysis.

EVIDENCE ACQUISITION

Systematic literature search was performed to identify relevant randomized controlled trials (RCTs) for the review. The primary outcomes for the study were stone-free rate (SFR) and blood transfusion rate. The secondary outcomes were complication rates, fever, fall in hemoglobin, operative time, length of stay (LOS), need for auxiliary procedure, and visual analog scale (VAS) score at 24 h. We followed Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, and the study protocol was registered with PROSPERO in priori (CRD42021252444).

EVIDENCE SYNTHESIS

In this review, 16 RCTs with 3961 patients were included. SFR was comparable between the two groups (risk ratio [RR] 1.01 [0.99, 1.04], p = 0.30), whereas the need for transfusion was lower with mPNL (RR 0.54 [0.37, 0.78], p = 0.001). Fall in hemoglobin (mean difference [MD] -0.67 [-0.93, -0.41], p = 0.000) and LOS (MD -0.59 [-0.81, -0.37], p = 0.000) were shorter with mPNL. Operative time was significantly shorter with sPNL (MD 8.28 [3.96, 12.59], p = 0.000). Complications were lower with mPNL (RR 0.89 [0.79, 0.97], p = 0.01). The need for auxiliary procedures (RR 0.77 [0.58, 1.03], p = 0.08) and VAS at 24 h (MD -0.79 [-1.63, 0.05], p = 0.06) were similar in the two groups.

CONCLUSIONS

Mini PNL has similar efficacy to sPNL in terms of SFRs. However, mPNL has a superior safety profile with fewer overall complications and a reduced need for blood transfusion.

PATIENT SUMMARY

In this study, we conducted a meta-analysis comparing mini and standard percutaneous nephrolithotomy (PNL) for the management of patients with renal stone disease. We showed that mini and standard PNL are associated with similar stone-free rates. Overall complications and the need for blood transfusion were lower with mini PNL.

Is There Still a Place for Percutaneous Nephrolithotomy in Current Times?

Background: Percutaneous nephrolithotomy (PCNL) and its miniaturized modifications are usually considered the standard surgical options for large (>20 mm) staghorn and infected stones. Moreover, PCNL is a viable alternative to retrograde intrarenal surgery (RIRS) for smaller stones (<20 mm) in the presence of anatomical malformations or inaccessible lower pole stones. However, due to the advancements in laser and scope technology, RIRS is expanding its indications with the potential benefits of lower complications and a shorter hospital stay. Methods: A literature search using the PUBMED database from inception to June 2022 was performed to explore the current role of PCNL in endourology. The analysis involved a narrative synthesis. Results: PCNL confirmed its role in the treatment of large and complex stones; moreover, miniaturized PCNL has become more competitive, gaining space among classic indications of flexible ureteroscopy. Conclusions: considering all the evaluated subgroups, we can conclude that PCNL is an old fascinating procedure and is here to stay.

A prospective, single-centered, cohort study comparing the treatment of renal stones by following PCNL types: Standard, tubeless & totally tubeless

Introduction

Renal stones are a frequent cause of morbidity globally. The number of lumbotomies performed for benign lithiasis has been greatly decreased with the usage of Percutaneous Nephrolithotomy (PCNL). Further development is aimed at reducing tract size, leading to numerous advanced minimally invasive PCNL procedures like mini-PERC, ultra-mini-PERC, and micro-PERC. The aim of this study was to evaluate whether tubeless or totally tubeless PCNL is the safest and most efficient, less morbid management technique for renal stones compared to the standard PCNL with a nephrostomy tube.

Methodology

This is a comparative, prospective, single-centered, cohort study that took place between August 2015 and January 2018 in the Urology department of Benazir Bhutto Hospital in Rawalpindi, Pakistan. 218 patients having single/multiple stones of variable sizes were enrolled in the study. Participants were stratified into three groups; Group A: Standard PCNL treatment; Group B: Tubeless PCNL treatment; Group C Totally Tubeless treatment. Mean operation time (±SD) and stone-free rates were our primary outcomes. The rate of complications during and post-operative complications were our secondary outcomes.

Results

A total of 181 patients were included in our study. A decreasing trend can be seen in mean operation time as we move from Group A to Group C (p = 0.000). The rate of problems during operation in each group was highest (45.8%) in Group A, much lesser problems in Group C (13.3%), and least problems in Group B (8.1%) (p = 0.000). The postoperative complication rate was again the highest in Group A (30.5%), low in Group C (8.3%), and extremely low in Group B (1.6%)

Conclusion

Tubeless PCNL proved to be the safest and most effective when compared to standard and totally tubeless PCNL procedures. It also showed the highest stone-free rates and least ‘unsatisfactory’ results amongst all the groups. Conclusively, it should be performed in routine preferably.

•

In terms of safety and efficacy, tubeless PCNL outperformed both regular and completely tubeless PCNL.

•

The Tubeless PCNL is much superior than other techniques of PCNL.

•

Aftercare and difficulties during surgery are virtually nonexistent with tubeless PCNL.

•

Stone-free rates were also the highest and the least “unsatisfactory” across all groups. Finally, it's best if it's done on a regular basis.

Wireless implantable optical probe for continuous monitoring of oxygen saturation in flaps and organ grafts

Continuous, real-time monitoring of perfusion after microsurgical free tissue transfer or solid organ allotransplantation procedures can facilitate early diagnosis of and intervention for anastomotic thrombosis. Current technologies including Doppler systems, cutaneous O2-sensing probes, and fluorine magnetic resonance imaging methods are limited by their intermittent measurements, requirements for skilled personnel, indirect interfaces, and/or their tethered connections. This paper reports a wireless, miniaturized, minimally invasive near-infrared spectroscopic system designed for uninterrupted monitoring of local-tissue oxygenation. A bioresorbable barbed structure anchors the probe stably at implantation sites for a time period matched to the clinical need, with the ability for facile removal afterward. The probe connects to a skin-interfaced electronic module for wireless access to essential physiological parameters, including local tissue oxygenation, pulse oxygenation, and heart rate. In vitro tests and in vivo studies in porcine flap and kidney models demonstrate the ability of the system to continuously measure oxygenation with high accuracy and sensitivity.

Totally ultrasound-guided minimally invasive percutaneous nephrolithotomy in children: Is it safe?

OBJECTIVE

The objective of the study was to assess the outcome and feasibility of ultrasonography (US)-guided minimally invasive percutaneous nephrolithotomy (mini-PCNL) in children.

MATERIALS AND METHODS

Twenty-five children with upper urinary tract stones who had undergone US-guided mini-PCNL from June 2017 to June 2020 were enrolled in this study. Patients' demographic information and post-treatment results were retrospectively gathered and analysed. Pyelocaliceal system was punctured in prone position using US guidance, and the tract was dilated using single-shot dilation technique. All steps of renal access were done using only US. Mini-PCNL in all cases was done by using 15 Fr rigid nephroscope. Stones were fragmented with a pneumatic lithotripter and evacuated.

RESULTS

The patients' mean age was 6.30 ± 3.25 years (range: 1.5-15). The mean stone size was 16.04 ± 3.93 mm (range: 10-30). The mean access time to the stone was 1.50 ± 0.62 min (range: 1-4). The mean operation time was 94.66 ± 3.05 min (range: 90-100 min). The final stone-free rate was 96%. Post-operation fever occurred in 4 (16%) patients who were treated successfully with an antibiotic. No major complications occurred.

CONCLUSIONS

We recommend US-guided mini-PCNL as a harmless alternative treatment option, in children with renal calculi due to its excellent outcomes and little complications.

Flank free modified supine versus prone ultra mini percutaneous nephrolithotomy in treatment of medium sized renal pelvic stone a randomized clinical trial

INTRODUCTION & OBJECTIVES

percutaneous nephrolithotomy (PNL) is the standard treatment of renal stone more than 2 cm. ultra-mini-percutaneous nephrolithotomy had emerged in the last decade as a new technique in treating renal stones less than 2 cm. in this study we compare between outcomes of (UMP) in modified flank free supine (FFSP), and prone position.

MATERIALS & METHODS

A prospective randomized study was conducted between January 2016 and April 2020, including 122 patients, divided into two matched groups. Group A included 61 patients who underwent UMP in FFSP, and group B included 61 patients who underwent UMP in a prone position. All patients had a single renal pelvic stone 1-2 cm. Patients with a single kidney, renal anomalies, BMI≥40, history of ipsilateral renal surgery, and age less than 18 years were excluded. In both groups, the dilatation was done up to 13 f; a holmium laser was used through a 9f ureteroscope for fragmentation. Nephrostomy tube and ureteric stent were used only when indicated.

RESULTS

122 patients who divided into two groups. The mean age was 40.09±13.63 and 39.67±13.80 years in both groups, respectively. The operative time was 63.64±9.22 and 78.48±9.55 minutes in groups A &B, respectively (P=0.0001). The fluoroscopy time was 3.47±0.56 and 4.45±0.39 minutes in groups A &B, respectively (P=0.0001).no significant difference between both groups regarding operative and post-operative complications. Shift to miniPNL was needed in one patient in group A and four patients in group B due to impaired vision. The hospital stay was 25.36±4.23 and 26.13±4.76 hours in both groups, respectively. The initial stone-free rate was 95.1% and 91.8% in both groups, respectively.

CONCLUSIONS

ultra-mini-percutaneous nephrolithotomy in modified supine position shows comparable results to the prone position regarding stone-free rate, hospital stay, and perioperative complication, with significantly shorter operative and fluoroscopy time.

Does nephrolithometry scoring systems predict success and complications in miniPCNL?

OBJECTIVE

Auxiliary nephrolithometric scoring systems (NSSs) have been developed to predict complications and treatment success of conventional percutaneous nephrolithotomy (PCNL). However, to our knowledge, there is no study comparing these NSSs in patients undergoing miniPCNL. This study aimed to compare the NSSs in terms of their ability to predict miniPCNL-related complications and treatment success.

METHODS

The data of patients undergoing PCNL between September 2016 and May 2018 were retrospectively reviewed through the electronic medical record system, and 140 patients were included in our study. Stone-free status was evaluated using non-contrast computed tomography between 1 and 3 months after the procedure. PCNL was considered successful if the patient was completely stone free. The postsurgical complications were classified according to the modified Clavien-Dindo classification system.

RESULTS

The Clinical Research Office of the Endourological Society (CROES) and STONE NSSs significantly predicted miniPCNL treatment success (p = 0.043, p = 0.018). However, the Guy's NSS did not significantly predict the treatment success (p = 0.415). Guy's, CROES and STONE NSSs were not found to significantly predict postsurgical complications (p = 0.584, p = 0.823, p = 0.189).

CONCLUSION

To the best of our knowledge, our study is the first of its kind to investigate the ability of NSSs to predict treatment success and postsurgical complications in patients undergoing miniPCNL. The study found that STONE and CROES NSSs are independent parameters for predicting stone-free status after miniPCNL. In addition, our study found that none of the NSSs were useful in predicting postsurgical complications in patients undergoing miniPCNL.

Mini percutaneous nephrolithotomy versus standard percutaneous nephrolithotomy for the management of renal stones over 2 cm: a systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

Standard percutaneous nephrolithotomy (sPCNL) is recommended for renal stones over 2cm. Mini percutaneous nephrolithotomy (mPCNL) has also emerged as a promising technique in this setting. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing the safety and efficacy of sPCNL to mPCNL for the management of renal stones over 2cm.

EVIDENCE ACQUISITION

We systematically searched PubMed, Cochrane Library and Scopus databases until April 2021 and sources of grey literature for relevant RCTs. We performed a meta-analysis of odds ratios (ORs) to compare bleeding or other complications and stone-free rate (SFR) between sPCNL and mPCNL. Similarly, we undertook a metaanalysis of weighted mean differences for the mean operative and hospitalization time between the two techniques (PROSPERO: CRD42021241860).

EVIDENCE SYNTHESIS

Pooled data from 8 RCTs (2535 patients) were available for analysis. sPCNL was associated with a higher hemoglobin drop (0.59g/dl, 95%CI: 0.4-0.77, I2=93%), higher likelihood of postoperative blood transfusion (OR: 2.58, 95%CI: 1.03-6.45, I2=30%) and longer hospital stay (0.75 days, 95%CI: 0.45-1.05, I2=73%) compared to mPCNL. No significant differences were demonstrated in SFR (OR: 0.92, 95%CI: 0.74-1.16, I2=0%) and mean operative time (4.05 minutes, 95%CI: -9.45-1.37, I2=91%) after sPCNL versus mPCNL. Similarly, no significant differences were observed for postoperative fever, pain and Clavien-Dindo complications.

CONCLUSIONS

mPCNL represents a safe and effective technique and may be also recommended as a first-line treatment modality for well-selected patients with renal stones over 2cm. Still, further high-quality RCTs on the field are mandatory, since the overall level of evidence is low.

Super-mini percutaneous nephrolithotomy (SMP) vs retrograde intrarenal surgery (RIRS) in the management of renal calculi ≤ 2 cm: a propensity matched study

OBJECTIVE

To compare the effectiveness and safety of Super-Mini PCNL (SMP) and Retrograde Intrarenal Surgery (RIRS) in the management of renal calculi ≤ 2 cm.

PATIENTS AND METHODS

A prospective, inter-institutional, observational study of patients presenting with renal calculi ≤ 2 cm. Patients underwent either SMP (Group 1) or RIRS (Group 2) and were performed by 2 experienced high-volume surgeons.

RESULTS

Between September 2018 and April 2019, 593 patients underwent PCNL and 239 patients had RIRS in two tertiary centers. Among them, 149 patients were included for the final analysis after propensity-score matching out of which 75 patients underwent SMP in one center and 74 patients underwent RIRS in the other. The stone-free rate (SFR) was statistically significantly higher in Group 1 on POD-1 (98.66% vs. 89.19%; p = 0.015), and was still higher in Group 1 on POD-30 (98.66% vs. 93.24%, p = 0.092) SFR on both POD-1 and POD-30 for lower pole calculi was higher in Group 1 (100 vs. 82.61%, p = 0.047 and 100 vs 92.61% p = 0.171). The mean (SD) operative time was significantly shorter in Group 1 at 36.43 min (14.07) vs 51.15 (17.95) mins (p < 0.0001). The mean hemoglobin drop was significantly less in Group 1 (0.31 vs 0.53 gm%; p = 0.020). There were more Clavien-Dindo complications in Group 2 (p = 0.021). The mean VAS pain score was significantly less in Group 2 at 6 and 12 h postoperatively (2.52 vs 3.67, 1.85 vs 2.40, respectively: p < 0.0001), whereas the mean VAS pain score was significantly less in Group 1 at 24 h postoperatively (0.31 vs 1.01, p < 0.0001). The mean hospital stay was significantly shorter in Group 1 (28.37 vs 45.70 h; p < 0.0001).

CONCLUSION

SMP has significantly lower operative times, complication rates, shorter hospital stay, with higher stone-free rates compared to RIRS. SMP is associated with more early post-operative pain though.

Use of retrograde intrarenal surgery (RIRS) compared with mini-percutaneous nephrolithotomy (mini-PCNL) in pediatric kidney stones

OBJECTIVE

We aimed to compare the cost-effectiveness and safety of retrograde intrarenal surgery (RIRS) and mini-percutaneous nephrolithotomy (mini-PCNL) for pediatric kidney stones management.

PATIENTS AND METHODS

Ninety pediatric patients with single or multiple renal stones 1-3 cm in diameter were collected prospectively and equally divided into two groups to undergo RIRS or mini-PCNL. The groups were compared for fluoroscopy and operative time, postoperative hospital stay time, stone-free rate (SFR), need for auxiliary procedures, and cost as well as complications.

RESULTS

There were no differences found between RIRS and mini-PCNL groups with regard to operative time and postoperative DJ stent application, while the mean of fluoroscopy time and postoperative hospital stay was significantly shorter in the RIRS than in the mini-PCNL group. The SFR, auxiliary treatment on residual stones, and complications were comparable. In both groups, no major (Clavien IV-V) complications were observed. The mean cost of RIRS was $1210 and $733 for the mini-PCNL.

CONCLUSIONS

Both RIRS and mini-PCNL are effective and safe treatment modalities for pediatric renal stones 10-30 mm in size. However, mini-PCNL is more cost-effective making it a viable alternative to RIRS.

Size Distribution of Fragments by High-power Holmium Laser Lithotripsy in MiniPCNL with Suction

PURPOSE OF REVIEW

Data are lacking on distribution of size of fragments created with the laser lithotripsy, stone density, and composition. Dust (< 1 mm) and small fragments (1-3 mm) may be too small to be efficiently removed with forceps compared to larger fragments (> 3 mm). We aim to report the size distribution of fragments formed during holmium laser lithotripsy.

RECENT FINDINGS

One hundred ten patients with renal calculi < 3 cm underwent miniPCNL using ClearPetra sheath (Well Lead Medical Co., China) with controllable irrigation and suction system that minimizes fragment dispersion and maximizes fragment aspiration. Moses holmium laser (Lumenis INC, Israel) was used with predefined laser energy settings for lithotripsy. Proportion of fragment size < 1 mm was 46.36 ± 16.68%, 1-3 mm was 28.18 ± 10.01%, and > 3 mm was 25.19 ± 16.18% for the entire cohort. Complete stone clearance at 48 h was achieved in 77.3% cases. The remaining 22.7% patients had complete clearance at 1-month follow-up CT. In all the stone density, volume, and composition groups, majority of fragments created were either < 1 mm or 1-3 mm. Only 25% fragments were > 3 mm that would get aspirated out through the sheath with suction or could be retrieved with forceps. The combination of a high-power holmium laser and suction would help in complete stone clearance with effective aspiration of smaller stone fragments and dust simultaneously during lasing.

Comparison of Vacuum Suction Sheath and Non-Vacuum Suction Sheath in Minimally Invasive Percutaneous Nephrolithotomy: A Meta-Analysis

Objective To evaluate the clinical efficacy of minimally invasive percutaneous nephrolithotomy (mPCNL) with vacuum suction sheath in the treatment of renal calculi. Methods: We collected relevant studies of vacuum suction sheath and non-vacuum sheath mPCNL from PubMed, Embase, and Cochrane databases for a meta-analysis following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Results: 7 studies were included (4 randomized controlled studies, 3 retrospective studies involving 1803 patients). The final meta-analysis results showed that the operative time (Standardised Mean Difference [SMD] = -0.84, 95% CI [-1.20; -0.48], P < 0.001), auxiliary procedures (Odds Ratio [OR] = 0.61, 95% CI [0.46; 0.81], P < 0.001) and complications in the vacuum suction sheath group were significantly lower than those in the non-vacuum sheath group. The immediate and final stone-free rates (OR = 1.69, 95% CI [1.30; 2.18], P < 0.001; OR = 1.44, 95% CI [0.98; 2.13], P = 0.039) were also significantly lower in the vacuum suction sheath group. Conclusion: This study indicates that the application of vacuum suction sheath in mPCNL can significantly shorten the operative time and patient hospitalization, reduce auxiliary procedures and complications (especially fever, urinary tract infection, and pain).

Ultra-mini-percutaneous nephrolithotomy in flank-free modified supine position versus prone position in treatment of pediatric renal pelvic and lower calyceal stones

OBJECTIVES

To report the safety and efficacy of ultra-mini-percutaneous nephrolithotomy (UMPCNL) in flank free modified supine (FFMS) and prone positions in management of pediatric renal calculi.

PATIENTS & METHODS

This prospective randomized study included 55 pediatric patients with symptomatic renal stones and suitable for ultra-mini-percutaneous nephrolithotomy. They were randomized into two groups. Group A included 28 patients who were treated by UMPCNL in FFMS position (with a pad below the ipsilateral shoulder and buttocks, putting ipsilateral upper limb over the chest, and crossing the extended ipsilateral lower limb over the flexed contralateral one) and Group B included 27 patients treated by UMPCNL in the prone position. In both groups dilatation was done to 13 French sheath allowing the introduction of 6/7.5 French semi-rigid ureteroscope and fragmentation of stones by Ho:YAG laser with a 550-μm fiber laser lithotripter.

RESULTS

The operation time in FFMS position UMPCNL group was significantly shorter than prone position UMPCNL group (84.3±9.87 vs. 99.3±8.75) minutes with p=0.022. There was no significant difference between both groups in terms of stone free rate (89.3% vs. 88.9%), overall complication rate (including transient fever) (21.4% vs. 18.5%), post-operative pain (VAS score) (3.4±0.8 vs. 3.3±0.9), or hospital stay (3.53±0.8 vs. 4.1±1.1) days.

CONCLUSION

Both ultra-mini-percutaneous nephrolithotomy in FFMs and prone positions are feasible, safe and effective in treatment of pediatric renal stones with relatively shorter operative time in FFMS position.

Mini Percutaneous Kidney Stone Removal: Applicable Technologies

Percutaneous nephrolithotomy (PCNL) remains the treatment of choice for large and complex renal stones. The technological advances over the past several decades gave birth to different varieties of minimally invasive PCNLs, including the mini-PCNL, ultra-mini PCNL, super mini-PCNL, and micro-PCNL, with indications being extended to stones even larger than 20 mm. This article provides an update of all these available techniques of miniaturized PCNL along with its anatomic and physiologic impact. This should assist urologists in providing a personalized approach to the patient based on various patient- and stone-related factors to provide the best of all available technology for treatment.

Comparison of Micro-Percutaneous and Mini-Percutaneous Nephrolithotomy in the Treatment of Renal Stones: A Systematic Review and Meta-Analysis

Background: To assess the efficacy and safety of micro-percutaneous nephrolithotomy (Microperc) and mini-percutaneous nephrolithotomy (Miniperc) in the treatment of moderately sized renal stones. Methods: Literature search of PubMed, Web of Science, and Embase was performed prior to January 2021. We used odds ratios (OR) and weighted mean difference (WMD) for dichotomous variables and continuous variables, respectively. Results were pooled using Review Manager version 5.3 software. Results: A total of six studies involving 291 Microperc and 328 Miniperc cases was included. The overall stone-free rate (SFR) of Microperc was 87.29% (254/291), while the SFR of Miniperc was 86.59% (284/328). Microperc was associated with lower hemoglobin drop (WMD: -0.98; P = 0.03) and higher renal colic requiring D-J stent insertion (OR: 3.49; P = 0.01). No significant differences existed between Microperc and Miniperc with respect to SFR (OR: 1.10; P = 0.69), urinary tract infection (OR: 0.38; P = 0.18), operative time (WMD: -5.76; P = 0.62), and hospital stay time (WMD: -1.04; P = 0.07). Conclusions: Our meta-analysis demonstrated that Microperc could produce an SFR that was comparable with that of Miniperc. Microperc was associated with lower hemoglobin drop, while Miniperc was associated with lower renal colic rates. In addition, the operation time and hospital stay time for both these procedures were similar.

Comparison of mini percutaneous nephrolithotomy and standard percutaneous nephrolithotomy for renal stones >2cm: a systematic review and meta-analysis

BACKGROUND

The purpose is to compare the efficacy and safety of mini percutaneous nephrolithotomy (mini-PCNL) versus standard percutaneous nephrolithotomy (standard-PCNL) in patients with renal stones >2cm.

MATERIALS AND METHODS

A systematic literature search was conducted in PubMed, Web of Science, Scopus, and the Cochrane Library databases to identify relevant studies before March 8, 2021. Stone-free rate (SFR), operation time, fever rate, hemoglobin drop, blood transfusion rate, and hospitalization time were used as outcomes to compare mini-PCNL and standard-PCNL. The meta-analysis was performed using the Review Manager version 5.4.

RESULTS

Seven randomized controlled trials were included in our meta-analysis, involving 1407 mini-PCNL cases and 1436 standard-PCNL cases. Our results reveal that, for renal stones >2cm, mini-PCNL has a similar SFR (risk ratio (RR)=1.01, 95% confidence interval (CI): 0.98 to 1.04, p=0.57) and fever rate (RR=1.22, 95% CI: 0.97-1.51, p=0.08). Standard-PCNL was associated with a significantly shorter operating time (weighted mean difference (WMD)=8.23, 95% CI: 3.44 to 13.01, p <0.01) and a longer hospitalization time (WMD=-20.05, 95% CI: -29.28 to -10.81, p <0.01) than mini-PCNL. Subgroup analysis showed hemoglobin drop and blood transfusion for 30F standard-PCNL were more common than mini-PCNL (WMD=-0.95, 95% CI: -1.40 to -0.50, p <0.01; RR=0.20, 95% CI: 0.07 to 0.58, p <0.01).

CONCLUSION

In the treatment of >2cm renal stones, mini-PCNL should be considered an effective and reliable alternative to standard-PCNL (30F). It achieves a comparable SFR to standard-PCNL, but with less blood loss, lower transfusion rate, and shorter hospitalization. However, the mini-PCNL does not show a significant advantage over the 24F standard-PCNL. On the contrary, this procedure takes a longer operation time.

TRIAL REGISTRATION

This meta-analysis was reported consistent with the PRISMA statement and was registered on PROSPERO, with registration number 2021CRD42021234893.

Changes in percutaneous approach to kidney stones in children: A single institute experience over 500 cases

PURPOSE

The aim of this study is to identify the changes in patient age and stone sizes with technological advancement over time.

METHODS

This study was conducted retrospectively with 404 patients (504 renal units) who underwent percutaneous nephrolithotomy (PCNL) between January 1997 and June 2020. Patient characteristics and trends on instrument preferences were investigated.

RESULTS

Median age was 7 (1-18) years. Male to female ratio was 1.48:1 (301/203). Median stone burden was 2 cm² (0.20-25) and median operative time was 90 minutes (20-240). The stone-free rate was 74.6%. Patients were divided into four groups according to the size of the instrument. It was found that the size of sheath used increased significantly with increasing age and stone burden. The micro-PCNL group had the shortest hospitalisation and lowest blood transfusion rate. Chronologically categorised four equal groups were compared to analyse changing patient profiles and trends. Median patient age, stone burden, operation time, sheath size, blood transfusion and complication rates decreased significantly with time. However, the use of tracts smaller than 20F and the number of patients with previous intervention increased significantly.

CONCLUSION

Our study demonstrated that the patient's age and stone size at the time of initial diagnosis decrease over time while miniaturisation techniques increase in paediatric urology.