Mini PCNL for renal calculi: does size matter?

Is percutaneous nephrolithotomy effective and safe in infants younger than 2 Years old? Comparison of mini standard percutaneous nephrolithotomy

BACKGROUND

In this study, we aimed to compare the operative outcomes, postoperative outcomes, stone-free status and complications of SPCNL and MPCNL in infants younger than two years of age.

METHODS

We retrospectively analyzed 163 patients younger than two years of age who underwent percutaneous nephrolithotomy (PCNL) in our institution between September 1999 and March 2022. The patients were divided into two groups depending on the tract size. The MPCNL group consisted of 73 patients with a tract of 22 Fr or less, and the SPCNL consisted of 90 patients with a tract greater than 22 Fr.

RESULTS

The median age of 163 patients included in the study was 17.3 (range 7-24) months. Although the median stone size was lower in the SPCNL group, no statistically significant difference was found between the two groups in terms of stone size (p = 0.073). The median operative time was 74.8 min in the MPCNL group and 62.8 min in the SPCNL group, with a statistically significant difference (p = 0.002). Stone free rates (SFR) were 89 % and 90.8 % in the MPCNL and SPCNL groups, and the clinically insignificant residual fragments (CIRF) rates were 11 % and 4.6 %, respectively (p = 0.064). The fluoroscopy time, nephrostomy withdrawal time, and hospitalization stay were similar in the two PCNL groups (p = 0.535, p = 0.253, and p = 0.143, respectively). Postoperative fever was similar in MPCNL and SPCNL groups (p = 0.504). Although bleeding (6.7%-2.7 %) and blood transfusion (3.3%-1.4 %) rates were higher in the SPCNL group, there was no statistically significant difference (p = 0.248 and p = 0.420, respectively). Prolonged urinary leakage occurred in 6 (8.2 %) patients in the MPCNL group and 1 (1.1 %) patient in the SPCNL group, with a statistically significant difference (p = 0.026).

CONCLUSIONS

With the development of MPCNL, the use of SPCNL in infants has decreased considerably. However, SPCNL continues to be an effective and reliable method when needed in suitable patients. Although PCNL in infants shows some differences from adults, it is an effective and safe method for suitable patients.

LEVEL OF EVIDENCE

Although we created our study by retrospectively examining the pediatric urology data that we created prospectively, our study is of a retrospective nature. Therefore the Level of Evidence is 3.

The feasibility of ultrasound-guided mini-percutaneous nephrolithotomy for ESWL-resistant lower calyx renal stones of up to two centimeters: a single center experience

Lower pole renal stones present a significant challenge in urologic practice due to difficulty in accessing the calyx and eliminating fragments. Management options for these stones include watchful waiting for asymptomatic stones, extracorporeal shock wave lithotripsy (ESWL), ureterorenoscopy (URS), and percutaneous nephrolithotomy (PCNL). Mini-PCNL is a newer modification of conventional PCNL. The study aimed to assess the feasibility of mini-PCNL in treating lower pole renal stones equal to or less than 20mm that were not responsive to ESWL therapy. We included 42 patients (24 male and 18 female) with a mean age of 40±2.3 who underwent mini-PCNL at a single urology center between June 2020 and July 2022 and assessed operative and postoperative outcomes. The mean total operative time was 47±3.11 minutes, ranging from 40 to 60 minutes. The stone-free rate was 90%, and the overall complication rate was 26%, which included minor bleeding (5%), hematuria (7%), pain (12%), and fever (2%). The mean hospital stay was 80±3.34 hours (3-4 days). Our findings suggest that mini-PCNL is an effective treatment option for lower pole renal stones that are not responsive to ESWL therapy. The immediate stone-free rate was high, with minimum non-serious complications.

Comparison of the Efficacy and Complications of Soft Ureteroscopy Lithotripsy and Percutaneous Nephrolithotomy in the Treatment of Urinary Calculi: A Systematic Review and Meta-analysis

Objective

To systematically evaluate the efficacy and complications of soft ureteroscopic lithotripsy (SUL) and percutaneous nephrolithotomy (PCNL) in the treatment of urinary calculi and to provide evidence-proof medicine basis for the popularization and application of flexible ureteroscopic lithotripsy.

Methods

PubMed, EMBASE, ScienceDirect, Cochrane Library, China knowledge Network Database (CNKI), China VIP Database, Wanfang Database, and China Biomedical Literature Database (CBM) were searched for randomized controlled trials (RCT) related to soft ureteroscopic lithotripsy and percutaneous nephrolithotomy in the treatment of urinary calculi from Jan. 2010 to Mar. 2022. The bias risk of each included literature was assessed according to the standard of Cochrane manual 5.1.0. The collected data were meta-analyzed by RevMan 5.4 statistical software.

Results

Ultimately, 6 RCT (a total of 794 samples) were included for meta-analysis. Heterogeneity test results of stone clearance rate were chi² = 2.44, df = 5, P = 0.79 > 0.05, and I² = 0%, indicating none obvious heterogeneity among the included research data. The test of WMD was Z = 2.11 (P = 0.03). It could be considered that compared with PCNL in the treatment of urinary calculi, SUL had a higher stone clearance rate in patients with urolithiasis. Secondly, heterogeneity test of operation time was chi² = 184.95, df = 5, P < 0.00001, and I² = 97%. The results of heterogeneity test of intraoperative blood loss displayed chi² = 645.47, df = 5, P < 0.00001, and I² = 99%. Then, heterogeneity test results of postoperative hospital stay existed chi² = 57.37, df = 5, P < 0.00001, and I² = 91% with an obvious heterogeneity. According to the results of this analysis, it could be considered that compared with PCNL in the treatment of urolithiasis, the operation time of SUL in the treatment of urolithiasis was longer, but the amount of intraoperative bleeding and postoperative hospital stay was significantly reduced. The results of heterogeneity of stress index level NE showed as chi² = 0.32, df = 2, P = 0.85 > 0.05, and I² = 0%, and COR was chi² = 1.09, df = 1, P = 0.30 > 0.05, and I² = 8%. It showed that there was no obvious heterogeneity. The heterogeneity of ACTH was chi² = 390.36, df = 2, P < 0.00001, and I² = 99%, suggesting obvious heterogeneity. The test of combined effect dose WMD was Z = 21.90, 4.50, and 15.42, (P < 0.00001). It could be considered that there was a statistical difference in the WMD of stress response between patients with urinary calculi treated by soft ureteroscope and percutaneous nephrolithotomy, indicating that the stress response of patients with urinary calculi treated with SUL is less than that of PCNL. For the heterogeneity test of serum creatinine level, NE showed chi² = 0.78, df = 2, P = 0.68 > 0.05, and I² = 0% without obvious heterogeneity, and the combined effect dose WMD is analyzed by random effect model. The test of combined effect dose WMD was Z = 4.22 (P < 0.00001). It can be considered that the improvement of serum creatinine level in patients with urolithiasis treated with SUL was better than that of PCNL. The results of heterogeneity test on the safety of operation are as follows: chi² = 13.76, df = 5, P = 0.02, and I² = 64%, indicating obvious heterogeneity among the included research data. The combined effect dose of WMD was Z = 5.53 (P < 0.00001). This could be considered that soft ureteroscopic lithotripsy had higher safety and less postoperative complications than percutaneous nephrolithotomy in the treatment of urinary calculi. An inverted funnel chart was used to analyze the publication bias of the study with stone clearance rate as the outcome index. The results showed that the figure was not completely symmetrical and the Egger's test showed that the figure was P = 0.0005 < 0.001. It was suggested that there may be a certain degree of publication bias.

Conclusion

PCNL and SUL can achieve higher stone clearance rate in the treatment of renal calculi. However, SUL has the advantages of less intraoperative bleeding, short stress reaction and postoperative hospital stay, less damage to renal function, and low incidence of complications, which is beneficial to the rapid recovery of patients after operation. More studies with higher methodological quality and longer intervention time are needed to further verify.

A retrospective analysis on the effect of single-channel minimally invasive percutaneous nephrolithotomy combined with retrograde flexible ureteroscopy using the completely lateral decubitus and semi-lithotomy positions to treat complex kidney stones

Background

Some types of complex kidney stones cannot be broken down and removed through single-channel percutaneous nephroscope or retrograde flexible ureteroscope. In order to be removed, these types of stones require multiple combined methods to be performed. The aim of this study was to retrospectively evaluate the clinical effect of single-channel minimally invasive percutaneous nephrolithotomy (mPCNL) combined with retrograde flexible ureteroscopy using the completely lateral decubitus and semi-lithotomy positions for treating complex renal calculi.

Methods

We selected 117 patients with complex renal calculi who were admitted to Peking University Shougang Hospital and Weifang People’s Hospital from January 1, 2017, to January 31, 2021. All patients were treated with single-channel mPCNL combined with retrograde flexible ureteroscopy in the completely lateral decubitus and semi-lithotomy positions. During the operation, the patients were placed in a completely lateral decubitus position, or their lower limbs were placed in a semi-lithotomy position for a single attempt only.

Results

An 18-Fr percutaneous channel was successfully established in all patients. The mean operation time was 112±37 minutes, and the average blood loss was 71±31 mL. A 14-Fr renal fistula was maintained for 7 days, a urethral catheter for 2–3 days, and a ureteral stent tube for 2 weeks after each surgery. According to the results of computed tomography (CT) scans performed 3–5 days after the operation, the total lithotripsy success rate reached 100%, with a first-stage lithotripsy rate of 98.29%. Two patients were found to each have 1 residual stone, with a diameter of 4 mm, left in kidney by CT, which then was to be removed under local anesthesia. The average postoperative hospitalized time was 7±2 days, and no severe complications occurred perioperatively.

Conclusions

Single-channel mPCNL combined with retrograde flexible ureteroscopy in the completely lateral decubitus and semi-lithotomy positions is a safe, feasible, and highly effective method of treating complex renal calculi, which is of benefit to save operation time and facilitate operation process, because patient’s position could not need to be changed repeatedly during the surgery.

THE FUNCTIONAL STATE OF THE RENAL PARENCHYMA AFTER VARIOUS VIDEO ENDOSURGICAL METHODS OF TREATMENT OF PATIENTS WITH LARGE AND COMPLEX KIDNEY STONES

The work is based on the analysis of literature data devoted to the problem of preserving the functional state of the kidneys with various video endoscopic methods of surgical treatment of large and complex kidney stones. The purpose of the review is to highlight the likelihood of deterioration in the functional state of the kidneys in the postoperative period. A detailed analysis of postoperative outcomes in various minimally invasive methods of treatment of patients with large and complex kidney stones was carried out, with an overview of the possibility of using dynamic nephroscintigraphy as a method of objectively assessing the functional state of the kidneys.

Outcome of Mini-Percutaneous Nephrolithotomy in Patients Under the Age of 18: An Experience With 112 Cases

Purpose: Renal calculi are becoming more common among children. Although, extracorporeal shock wave lithotripsy (ESWL) is the first choice in this age group, minimal invasive surgeries, such as percutaneous nephrolithotomy (PCNL), are indicated for some patients. Recently, PCNL devices have become smaller in size with acceptable efficacy and lower complications. We evaluated the outcomes and complications of mini-PCNL (MPCNL) surgery in our referral training centers.

Materials and Methods: Between September 2012 and January 2020, a total of 112 children under the age of 18, who had shown failure of ESWL, and/or their parents refused to do it, underwent MPCNL (15 Fr). The patients' profiles were reviewed for data collection including preoperative and stone data, operation information, and postoperative complications.

Results: Of 112 patients, 69 were boys, and 43 were girls. Their mean age was 8.6 years (14 months to 18 years). Mean stone size was 20 mm (14–34 mm). Seventy-four cases had renal pelvic stone, 22 had pelvis and lower pole, and 16 had staghorn. The mean operation time was 65 min (35–100 min), and mean radiation time was 0.6 min (0.2–1.4 min). Low-grade fever was detected in 14 patients (12.5%). Four patients needed blood transfusion and two had increased creatinine, which improved with conservative management. One patient developed urosepsis that resolved with antibiotic therapy. None of the patients had kidney perforation or other organ injury or death. Early stone-free rate (SFR) after operation was 90.2% (101 patients). Six patients had residual fragment <5 mm, which passed spontaneously in 2 weeks after operation (total SFR 95.3%). Three patients underwent second-look nephroscopy, and ureteroscopy was done for two patients due to migrated stone fragments to the distal ureter.

Conclusion: MPCNL is recommended as a safe alternative option for treatment of the nephrolithiasis in children with good outcome and acceptable complications.

A systematic review and meta-analysis of minimally invasive vs. standard percutaneous nephrolithotomy in the surgical management of renal stones

The present study aimed to assess current evidence on the effectiveness and safety of minimally invasive vs. standard percutaneous nephrolithotomy (PCNL) in the management of renal stones. A systematic search of electronic databases, which included PubMed, EMBASE and the Cochrane Library up to May 2019 was performed. Using Review Manager statistical software (version 5.3), primary outcomes, including stone-free rates (SFRs), were evaluated. Meanwhile, analysis was also performed to compare secondary outcomes, such as peri- and postoperative complications and operative data. Fourteen studies involving 1,611 patients with renal stones were analyzed based on the inclusion criteria. On the basis of the present analysis, mini percutaneous nephrolithotomy (MPCNL) was proven to have non-inferior clinical efficacy with respect to the SFR compared with PCNL [odds ratio (OR)=1.10; 95% confidence interval (CI), 0.84-1.44; P=0.48]. In addition, the meta-analysis showed that MPCNL had a significantly lower hemoglobin decrease [mean difference (MD)=-0.68; 95% CI, -1.05 to -0.31; P=0.0003] and fewer blood transfusions (OR=0.36; 95% CI, 0.18-0.71; P=0.003) compared with PCNL. Moreover, the MPCNL group had a shorter inpatient stay (MD=-0.81; 95% CI, -1.55 to -0.08; P=0.03) compared with the PCNL group. However, the overall evidence was insufficient to suggest a statistically significant difference in the adverse event profile for MPCNL compared with PCNL. The present meta-analysis indicates that MPCNL is an effective method for treating renal stones. Compared with PCNL, MPCNL not only has similarly high SFRs but is also associated with less blood loss, fewer blood transfusions, more favorable recovery time and shorter inpatient stays. However, the findings of the present study should be further confirmed by well-designed prospective randomized controlled trials with a larger patient series.

Stone clearance times with mini-percutaneous nephrolithotomy: Comparison of a 1.5 mm ballistic/ultrasonic mini-probe vs. laser

INTRODUCTION

A limitation of mini-percutaneous nephrolithotomy (mPCNL) is the narrow working channel of mini-nephroscopes, typically restricting instrumentation to 5 French (F) or smaller. We evaluated the efficacy of the 1.5 mm Swiss LithoClast ^® Trilogy (Trilogy) rigid probe and compared the results to consecutive cases performed with a 30 W Holmium:YAG (Ho:YAG) laser.

METHODS

A retrospective review of 30 consecutive mPCNL cases using the Trilogy and 30 W Holmium laser was performed. A 12 F MIPS nephroscope with a 16.5 F access sheath and 6.7 F working channel was used for all mPCNL cases. The Trilogy was used with a disposable 1.5 mm × 440 mm probe with dual ultrasonic and ballistic energy. The Ho:YAG laser was used with a 550 micron fibre and a maximum of 30 W. Stone clearance time (SCT) was defined by the total time interval between activation of the lithotripter until insertion of the nephrostomy tube and measured in mm²/minutes. SCT included time for fragment retrieval, equipment adjustments, and rigid and flexible nephroscopy during and after lithotripsy.

RESULTS

Eleven cases using a 1.5 mm Trilogy probe and 16 cases using a Ho:YAG laser met final inclusion criteria. Three cases using the Trilogy were excluded from final analysis due to conversion to alternative energy sources - two of those were upsized to standard PCNL and one was converted to laser. Mean stone diameter and density in the final Trilogy cohort was 26.7 mm and 1193 Hounsfield units (HU). Mean diameter and density in the laser cohort was 25.2 mm and 1049 HU. The mean stone area clearance time for Trilogy was 4.7±1.8 mm²/minute vs. 3.4±0.7 mm²/minute with Ho:YAG laser (p=0.21). For hard stones, defined as density >1000 HU, the Trilogy averaged 3.7±1.6 mm²/minutes, while the laser averaged 3.1±1.3 mm²/minutes (p=0.786). For soft stones, defined as <1000 HU, the Trilogy averaged 8.9±1.0 mm²/minutes compared to the Ho:YAG, which averaged 3.6±1.8mm²/minutes (p=0.019). No device-related complications occurred in either cohort.

CONCLUSIONS

The 1.5 mm mPCNL Trilogy probe was comparable to 30 W Ho:YAG laser for clearing hard stones. The Trilogy performed better than laser on soft stones with a HU density <1000 HU.

Use of a Novel Vacuum-Assisted Access Sheath in Minimally Invasive Percutaneous Nephrolithotomy: A Feasibility Study

Objective: To assess the safety and efficacy of a novel vacuum-assisted access sheath (VAAS) in minimally invasive percutaneous nephrolithotomy (MPCNL). Materials and Methods: Seventy-five consecutive patients with single renal pelvic stone were treated with MPCNL combined with a novel VAAS. Patients' demographics and surgical outcomes, as well as perioperative and postoperative data, were recorded. Matched-pair analysis in a 1:1 scenario was done in patients who underwent MPCNL by peel-away access sheath (PAAS). All MPCNL was done with a rigid 12F mini-nephroscope and an 18F access sheath. MINDRAY-PM9000 monitor was used to record the renal pelvic pressure (RPP) data. Results: Patients' demographics, stone size, burden, and density (HU) were comparable between the two groups. Operative time was significantly shorter in the study group, at a mean of 32.4 ± 9.6 vs 46.2 ± 11.8 minutes (p < 0.001). The immediate stone-free rate was 89.3% for the VAAS group and 77.3% for the PAAS group (p = 0.049). Patients in the VAAS group had a lower visual analogue pain scale score at postoperative 6 and 24 hours. Mean perioperative RPP was lower in the VAAS group (10.3 ± 4.3 vs 17.8 ± 5.1 mmHg, p < 0.001). More than 50 seconds of accumulative time of high RPP (>30 mmHg) was shown in 13 patients of the VAAS group vs 30 of the PAAS group (p = 0.002). Conclusion: Combining VAAS with high-power holmium laser in MPCNL significantly improves the efficiency of stone retrieval with low RPP. This novel approach also reduces operative time, postoperative fever, and pain due to its simultaneous suction property.

Present indications and techniques of percutaneous nephrolithotomy: What the future holds?

The purpose of the review was to present the latest updates on percutaneous nephrolithotomy (PCNL) procedure in terms of indications and evolving techniques, and to identify the advantages and disadvantages of each modality. The data for this review were collected after a thorough PubMed search in core clinical journals in English language. The key words included “PCNL” and “PNL” in combination with “indications”, “techniques”, “review” and “miniaturized PCNL”. Publications relevant to the subject were retrieved and critically reviewed. Current European and American Urology Association Nephrolithiasis Guidelines were included as well. The indications for standard PCNL have been changed through the past decade. Despite evolution of the procedure, innovations and the development of new technical approaches, the indications for miniaturized PCNL have not been standardized yet. There is a need for well-constructed randomized trials to explore the indications, complications and results for each evolving approach. A continuous reduction of tract size is not the only revolution of the last years. There is constant ongoing interest in developing new efficient miniature instruments, intracorporeal lithotripters and sophisticated tract creation methods. We can summarize that, PCNL represents a valuable well-known tool in the field of endourology. We should be open minded to future changes in surgical approaches and technological improvements.

Miniaturised percutaneous nephrolithotomy: Its role in the treatment of urolithiasis and our experience

Miniaturized percutaneous nephrolithotomy (PCNL) procedures have gained increased popularity in recent years. They aim to reduce percutaneous tract size in order to lower complication rates, while maintaining high stone-free rates. Recently, miniaturized PCNL techniques have further expanded, and can currently be classified into mini-PCNL, minimally invasive PCNL (MIP), Chinese mini-PCNL (MPCNL), ultra-mini-PCNL (UMP), micro-PCNL, mini-micro-PCNL, and super-mini-PCNL (SMP). However, despite its minimally-invasive nature, its potential superiority in terms of safety and efficacy when compared to conventional PCNL is still under debate. The aim of this review is to summarise different available modalities of miniaturized PCNL, details of instruments involved, and their corresponding safety and efficacy. In particular, this article highlights the role of the SMP and our experience with this novel technique in management of urolithiasis. Overall, miniaturized PCNL techniques appear to be safe and effective alternatives to conventional PCNL for both adult and pediatric patients. Well-designed, randomized studies are required to further investigate and identify specific roles of miniaturized PCNL techniques before considering them as standard rather than alternative procedures to conventional PCNL.