Percutaneous nephrolithotomy: technique

Operation time as a prognostic indicator on postoperative complications following percutaneous nephrolithotomy

Objective

We aimed to find an optimal cut-off time for percutaneous nephrolithotomy to prevent complications.

Methods

This study enrolled 165 patients aged 18-80 with renal stones ⩾2 cm or ⩾1 cm in lower pole, confirmed via noncontrast computed tomography. Baseline characteristics, stone features, operation time, and anesthesia time were recorded. Logistic regression models were fitted and the ability of the surgery time to predict complications, major complications, and systemic inflammatory response syndrome was evaluated using receiver-operating characteristic curves. Area under the receiver-operating characteristic curve analysis was used as a general indicator of quality.

Results

Out of 165 enrolled patients, 157 were analyzed (8 excluded due to follow-up and surgery data issues). The cohort consisted of 115 males (73.2%) and 42 females (26.7%), with a mean (SD) age of 47.4 (12.65) years. Multivariate analysis indicated that longer operation times and lower body mass index correlated with higher complication rates. A cut-off of 65 min for operation time showed 96.8% specificity for predicting complications. Additionally, 47.8% of patients were systemic inflammatory response syndrome positive postprocedure, and operation times were not shown to be predictive of systemic inflammatory response syndrome.

Conclusion

Operation time seemed to be a potential risk factor for postpercutaneous nephrolithotomy complications and lowering the operation time could prevent postoperative complications.

The relationship between map scores and complications after standard percutaneous nephrolithotomy

PURPOSE

Upper urinary tract stones are a common condition in urology clinics. Percutaneous nephrolithotomy (PCNL) is an effective procedure frequently used for the treatment of stones larger than 2 cm. MAP scoring is used to predict oncological outcomes and intraoperative complications after partial nephrectomy by using the thickness and adhesion of perinephric adipose tissue. We examined the relationship between MAP score and clinical and demographic findings of the patients, especially postoperative Hgb drop and postoperative complications.

MATERIAL-METHOD

Patients were divided into 2 groups: Those with MAP score < 3 and ≥ 3. The impact of the MAP score on the demographic, clinical, and surgical parameters of the groups was assessed and analyzed. The relationship between MAP score and complications based on Clavien Dindo classification was also examined. The study investigated factors affecting the development of complications, the amount of bleeding, and the influence of MAP scores on these outcomes.

RESULTS

The Hgb drop was 2.56 ± 1.00 in the group with a MAP score ≥ 3 which was statistically significantly higher than the group with a MAP score < 3 (1.43 ± 1.21) (p < 0.001). The stone-free rate was 81.7% in the group with a MAP score < 3, which was statistically significantly higher than the group with a MAP score ≥ 3 (59.6%) (p = 0.012).

CONCLUSION

As the MAP score of patients scheduled for standard PNL operation increased, there was a corresponding rise in Hgb drop, a decline in stone-free rates and an uptick in postoperative urinary complications of postoperative urinary infections.

Renal Access in Pediatric Supine Miniaturized Percutaneous Nephrolithotomy: Comparative Evaluation of Ultrasound-Fluoroscopy Combined and Biplanar (0°-90°) Fluoroscopic Techniques

Introduction: Ultrasound (US)-guided puncture has the benefits of avoiding radiation and limiting the risk of visceral injury. We aimed to evaluate the results of two different renal access techniques during pediatric supine mini percutaneous nephrolithotomy (smPCNL) in a comparative manner. Patients and Methods: Data obtained from pediatric patients undergoing smPCNL by single surgeon between September 2021 and 2023 were reviewed retrospectively. Children were divided into two groups namely; biplanar 0°-90° fluoroscopy (Group-F) and US-fluoroscopy combined (Group-C). In all cases, preoperative, operative, and postoperative findings were recorded. Success was defined as the determination of either no (complete stone-free status) or < 4 mm residual fragments (CIRF) on US and X-ray (postoperative 3rd month) images. Complications were evaluated according to modified Clavien-Dindo classification. Results: Data of 54 patients with a mean age of 8.6 years (Group-F = 30, Group-C = 24) are reviewed. In addition to the similar success rates in both groups (Group-F = 86.7% Group-C = 87.5% p = 0.928), similar minor complications were noted in the majority of the cases. No child required transfusion and/or angioembolization. Although the fluoroscopy and operation time were lower in Group-C, the difference was not statistically significant. Conclusion: US-fluoroscopy combined access technique can be applied with similar success and complication rates in pediatric smPCNL. Ultimately, as experience is gained, this technique may lower radiation exposure, although this was not observed in the current study.

Exploring the competency of the comprehensive complication index over the clavien-dindo classification in standard percutaneous nephrolithotomy: a call for better complication reporting

PURPOSE

The Comprehensive Complication Index (CCI) was introduced in 2013 to overcome the limitations of the Clavien-Dindo Classification (CDC) in grading postoperative complications. The objective of this study to assess the predictive value of the CDC and the CCI for postoperative course in patients undergoing standard adult percutaneous nephrolithotomy (PCNL).

METHODS

A retrospective analysis of 320 renal units that underwent standard PCNL between July 2021 - April 2023 was conducted. The CDC and CCI systems assessed complications occurring within the first 30 days after surgery. A second CCI score was calculated only on the highest CDC grade, and this score was referred to as the noncumulative CCI. A comparative analysis was conducted to determine the predictive efficacy of both evaluation methods regarding the postoperative course.

RESULTS

The postoperative complication rate was 23.1% (74/320). Eight patients (2.5%) experienced multiple complications, resulting in a higher total CCI score than the noncumulative CCI (p = 0.010). Correlation analysis revealed that the CCI correlated with the length of hospital stay (LOS) more precisely than the noncumulative CCI (CCI: r = 0.335; p = 0.004 vs. noncumulative CCI: r = 0.325; p = 0.005). Compared with patients with a single complication, those with multiple complications had similar demographics, preoperative stone characteristics, and intraoperative features.

CONCLUSION

Cumulative CCI proves to be a more effective predictor of LOS and complication burden in standard PCNL than CDC. Hence, using CCI to evaluate complications after PCNL may be a more appropriate approach.

Value of interventional radiology and their contributions to modern medical systems

Interventional radiology (IR) is a unique specialty that incorporates a diverse set of skills ranging from imaging, procedures, consultation, and patient management. Understanding how IR generates value to the healthcare system is important to review from various perspectives. IR specialists need to understand how to meet demands from various stakeholders to expand their practice improving patient care. Thus, this review discusses the domains of value contributed to medical systems and outlines the parameters of success. IR benefits five distinct parties: patients, practitioners, payers, employers, and innovators. Value to patients and providers is delivered through a wide set of diagnostic and therapeutic interventions. Payers and hospital systems financially benefit from the reduced cost in medical management secondary to fast patient recovery, outpatient procedures, fewer complications, and the prestige of offering diverse expertise for complex patients. Lastly, IR is a field of rapid innovation implementing new procedural technology and techniques. Overall, IR must actively advocate for further growth and influence in the medical field as their value continues to expand in multiple domains. Despite being a nascent specialty, IR has become indispensable to modern medical practice.

Impact of frailty on perioperative outcomes following percutaneous nephrolithotomy in older persons: evidence from the US Nationwide Inpatient Sample

To evaluate the impact of frailty on perioperative outcomes of older patients undergoing PCNL, utilizing the US Nationwide Inpatient Sample (NIS) database. Data of hospitalized patients ≥ 60 years who received PCNL were extracted from the 2010 to 2020 NIS database, and included demographics, clinical, and hospital-related information. Patients were assigned to low (< 5), medium (5-15), and high frailty risk (> 15) groups based on the hospital frailty risk score (HFRS). Associations between frailty risk and perioperative outcomes including total hospital cost were determined using population-weighted linear and logistic regression analyses. Data of 30,829 hospitalized patients were analyzed (mean age 72.5 years; 55% male; 78% white). Multivariable analyses revealed that compared to low frailty risk, increased frailty risk was significantly associated with elevated in-hospital mortality (adjusted odds ratio (aOR) = 10.70, 95% confidence interval (CI): 6.38-18.62), higher incidence of unfavorable discharge (aOR = 5.09, 95% CI: 4.43-5.86), prolonged hospital length of stay (LOS; aOR = 7.67, 95% CI: 6.38-9.22), increased transfusion risk (aOR = 8.05, 95% CI: 6.55-9.90), increased total hospital costs (adjusted Beta = 37.61, 95% CI: 36.39-38.83), and greater risk of complications (aOR = 8.52, 95% CI: 7.69-9.45). Frailty is a significant prognostic indicator of adverse perioperative outcomes in older patients undergoing PCNL, underscoring importance of recognizing and managing frailty in older patients.

Three-dimensional printing the navigation template for precise percutaneous renal puncture to treat pyonephrosis on a porcine model and a patient ：a case report

Objective

Percutaneous nephrolithotomy (PCNL) is the main method for pyonephrosis or lithotripsy in urology. However, it often comes with high risk, as the inaccurate puncture inevitably causes bleeding, intra- and post-operative complications. So, a new inter-disciplinary approach is needed to perform the puncture more accurately.

Methods

3 signs made of lead were marked onto the skin of the posterior side of the waist of a domestic pig or a patient, which was scanned by computed tomography (CT). Based on the CT images, the computer design and the 3D printing, a navigation template made of the transparent resin material is constructed. They were attached onto the surgical area on pig or patient according to the signs. During the PCNL, with this template, the puncture position, angle and depth were optimized in order to precisely enter the targeted renal pelvis or calices.

Results

With the 3D navigation templates, 18G puncture needles were used to enter the renal pelvis upon performing the PCNL on a porcine model and a patient. On the porcine model, the urine outflow was observed with minimal complication. Post-operative CT scans revealed that the needle was located in the renal pelvis. For the patient case, the puncture point was designed to target the calix with stone. No obvious bleeding and complication was found in renal puncture with template.

Conclusions

The navigation template was made with the combination of 3D printing, CT images and computer design. This template allows for accurate puncture of the renal pelvis or calix. Surgical improvement in kidney stones and pyonephrosis was observed in porcine model and patient case. In the future, prospective, trandomized, controlled clinical trials are needed to further confirm its advantage.

A Survey of Needle Steering Approaches in Minimally Invasive Surgery

In virtue of a curved insertion path inside tissues, needle steering techniques have revealed the potential with the assistance of medical robots and images. The superiority of this technique has been preliminarily verified with several maneuvers: target realignment, obstacle circumvention, and multi-target access. However, the momentum of needle steering approaches in the past decade leads to an open question-"How to choose an applicable needle steering approach for a specific clinical application?" This survey discusses this question in terms of design choices and clinical considerations, respectively. In view of design choices, this survey proposes a hierarchical taxonomy of current needle steering approaches. Needle steering approaches of different manipulations and designs are classified to systematically review the design choices and their influences on clinical treatments. In view of clinical consideration, this survey discusses the steerability and acceptability of the current needle steering approaches. On this basis, the pros and cons of the current needle steering approaches are weighed and their suitable applications are summarized. At last, this survey concluded with an outlook of the needle steering techniques, including the potential clinical applications and future developments in mechanical design.

Image-guided surgical planning of percutaneous nephrolithotomy with patient-specific CTRs

PURPOSE

We propose the utilization of patient-specific concentric-tube robots (CTRs) whose designs are optimized to enhance their volumetric reachability of the renal stone, thus reducing the morbidities associated with percutaneous nephrolithotomy procedures. By employing a nested optimization-driven scheme, this work aims to determine a single surgical tract through which the patient-tailored CTR is deployed. We carry out a sensitivity analysis on the combined percutaneous access and optimized CTR design with respect to breathing-induced excursion of the kidneys based on preoperative images. Further, an investigation is also performed of the appropriateness and effectiveness of the percutaneous access provided by the proposed algorithm compared to that of an expert urologist.

METHODS

The method is based on an ellipsoidal approximation to the renal calculi and a grid search over candidate skin areas and available renal calyces using an anatomically constrained kinematic mapping of the CTR. Percutaneous access is selected for collision-free CTR deployment to the centroid of the stones with minimal positional error at the renal calyx. Further optimization of the CTR design results in a robot tailored to the therapeutic anatomical features of each clinical case. The study examined 14 sets of clinical data of PCNL patients, analyzing stone reachability using preoperative images and breathing-induced motions of the kidney. An experienced urologist qualitatively assessed the adequacy of percutaneous access generated by the algorithm.

RESULTS

An assessment conducted by an expert urologist found that the percutaneous accesses produced by the proposed approach were found to be comparable to those chosen by the expert surgeon in most clinical cases. The simulated results demonstrated a mean volume coverage of 81.6 % ± 19.6 % for static anatomy and 63.7 % ± 27.7 % and 69.0 % ± 25.4 % when considering a 1 cm excursion of the kidney in the craniocaudal directions due to respiration or tool-tissue interaction.

CONCLUSION

The optimization-driven scheme for determining a single tract surgical plan, coupled with the use of a patient-specific CTR, shows promising results for improving percutaneous access in PCNL procedures. This approach clearly shows the potential for enhancing the quality and suitability of percutaneous accesses, addressing the challenges posed by staghorn and non-staghorn stones during PCNL procedures. Further research involving clinical validation is necessary to confirm these findings and explore the potential clinical benefits of the approach.

Comparison of safety and efficacy of tubeless vs. conventional mini percutaneous nephrolithotomy in patients with Escherichia coli bacteriuria

To evaluate the safety and efficacy of tubeless percutaneous nephrolithotomy (PCNL) in patients with Escherichia coli (E. coli) bacteriuria. We conducted a retrospective review of 84 patients with E. coli bacteriuria who underwent PCNL. Patients were divided into two groups according to whether a nephrostomy tube is placed at the end of the procedure. Preoperative clinical data, surgical outcomes, and postoperative complications were compared. Then, regression analysis of factors predicting success rate of PCNL in patients with E. coli bacteriuria was performed. After PCNL, residual fragments ≤ 4 mm were considered as success. At baseline, the two groups were similar with regard to age, gender, BMI, underlying disease, hydronephrosis, stone characteristics, and urinalysis. Postoperative fever occurred in 1 patient (3.8%) in the tubeless PCNL group, and in 5 patients (8.6%) in the conventional PCNL group (p > 0.05). There were no significant differences in terms of successful rate, decrease in hemoglobin, pain scores, blood transfusion, and hospitalization expenses. However, the tubeless PCNL group had significantly shorter operative time (60 vs. 70 min, p = 0.033), indwelling time of catheter (2 vs. 4 days, p < 0.001), and hospital stays (3 vs. 5 days, p < 0.001) than the conventional PCNL group. In the analysis of factors predicting success, the stone diameter, stone burden, and operative time were associated with success rate of PCNL. It is safe and effective to perform tubeless PCNL in patients with E. coli bacteriuria. Compared to conventional PCNL, tubeless PCNL accelerates patient recovery and shortens hospital stays.

Treatment of ureteropelvic junction obstruction in patients with renal calculi via laparoscopic pyeloplasty and flexible vacuum-assisted ureteral access sheath ureteroscopy: a multicenter retrospective observational study

BACKGROUND

Ureteropelvic junction obstruction (UPJO) is a common obstructive disease of the urinary tract. UPJO patients commonly exhibit coexistent renal calculi. The main aim of therapy is to relieve the obstruction and remove the stones at the same time.

METHODS

This retrospective study included 110 patients diagnosed with UPJO coexisting with multiple renal calculi at Shanxi Bethune Hospital and the First Hospital of Shanxi Medical University between March 2016 and January 2022. Patients were divided according to the methods used for dealing with UPJO and renal calculi. In Group A, patients underwent traditional open pyeloplasty and pyelolithotomy. In Group B, patients underwent percutaneous nephrolithotomy first and then laparoscopic pyeloplasty. In Group C, patients underwent flexible cystoscopy to remove stones and then laparoscopic pyeloplasty. In Group D, patients underwent flexible vacuum-assisted ureteral access sheath (FV-UAS)assisted flexible ureteroscopy (f-URS) and underwent laparoscopic pyeloplasty. The stones were broken up using a holmium laser. The pyeloplasty success rate, stone clearance rate, operation time, bleeding amount, complication occurrence rate, postsurgical pain, length of stay, and hospitalization cost were compared between the groups. The follow-up period was at least 2 years.

RESULTS

The use of f-URS and the FV-UAS, significantly increased the renal stone clearance rate and significantly reduced the complication incidence and operation time in UPJO patients with multiple coexisting renal calculi.

CONCLUSIONS

Laparoscopic pyeloplasty combined with f-URS and FV-UAS is safe and effective for treating UPJO in patients complicated by renal caliceal stones.

TRIAL REGISTRATION

Retrospectively registered.

Laparoscopic pyelotomy combined with ultrasonic lithotripsy via a nephroscope for the treatment of complex renal stones

The purpose of the study was to introduce a novel surgical approach of combining laparoscopic pyelotomy with ultrasonic lithotripsy via a nephroscope for the treatment of complex renal stones. Between May 2021 and April 2023, 32 patients underwent laparoscopic pyelotomy combined with ultrasonic lithotripsy via a nephroscope and their perioperative variables were retrospectively collected and outcomes were assessed. Dissection and incision of the anterior renal pelvis wall was performed via a laparoscope. A 19.5 F nephroscope was introduced into the renal pelvis through a laparoscopic trocar from the incision. Stones were fragmented and sucked out using a 3.3 mm ultrasonic probe placed through the nephroscope. All operations were completed successfully and the stone-free rate at 3 days after operation was 87.5% (28/32). Four (12.5%, 4/32) patients with staghorn stones had a small residual stone in the lower calyx after operation and did not require reintervention. No patient required perioperative transfusion and four (12.5%, 4/32) patients with struvite stones developed postoperative fever, which was successfully treated with intravenous antibiotics. The mean follow-up time was 14.0 ± 7.2 months, with no patient developing long-term complications. This approach offers a safe and effective treatment option for complex renal stones, as the method exhibits a high clearance rate with few complications.

A novel double-sheath negative-pressure versus conventional minimally invasive percutaneous nephrolithotomy for large kidney stone

This study aims to evaluate the therapeutic efficacy of a novel double-sheath negative-pressure minimally invasive percutaneous nephrolithotomy (D-mPCNL) compared to conventional minimally invasive percutaneous nephrolithotomy (C-mPCNL) for large kidney stones. A total of 132 patients diagnosed with large kidney stones in our hospital were included in the study. Among them, sixty-eight patients underwent D-mPCNL, while sixty-four underwent C-mPCNL. Parameters such as operative duration, stone-free rate, incidence of postoperative complications, and the need for auxiliary procedures were evaluated between the two groups. Compared to the C-mPCNL group, the D-mPCNL group demonstrated a significantly shorter operative time (41.97 ± 8.24 min vs. 52.30 ± 13.72 min; P < 0.000), lower rates of auxiliary procedures (5.9% vs. 17.2%; P = 0.041), and lower fever rates (2.9% vs. 14.1%; P = 0.021). The group also had a significantly higher primary stone-free rate (85.3% vs. 70.3%; P = 0.038). However, there were no statistically significant advantages in terms of the final stone-free rate, hemoglobin drops, and stone composition in the D-mPCNL group (P > 0.05). D-mPCNL is a novel surgical method that is safe and effective, reducing operative time, improving stone-free efficiency, and decreasing postoperative complications.

Endoscopic dilation using two guidewires: a novel approach for establishing access tract during percutaneous nephrolithotomy under ultrasonographic guidance

OBJECTIVE

To evaluate the efficacy and safety of a novel endoscopic dilation (END) method during percutaneous nephrolithotomy under ultrasonographic guidance.

METHODS

We retrospectively reviewed the clinical records of 138 patients who underwent percutaneous nephrolithotomy from June 2020 to December 2021. The patients were divided into three groups based on the method of nephrostomy tract creation: those who underwent fascial Amplatz serial fascial dilation (AMD) (n = 45), one-shot dilation (OSD) (n = 45), and END (n = 48). For END, a 20-Fr dilator with sheath was accessed over the first guidewire. A second guidewire was inserted into the collecting system via the endoscope. The nephroscope was then accessed to enlarge the renal puncture point using both guidewires. Demographic variables and important intraoperative and postoperative findings were compared among the three groups.

RESULTS

The preoperative characteristics were similar among the three groups. The END group had a significantly shorter access time than both the AMD and OSD groups and significantly less severe hemoglobin loss than the OSD group. There were no significant differences in the other important perioperative findings.

CONCLUSION

Use of this novel END method with two guidewires may be associated with less blood loss and a reduced access time.

Efficacy and safety of Kumpe access catheter for pre-percutaneous nephrolithotomy renal access in modified supine percutaneous nephrolithotomy

INTRODUCTION

Traditionally, a pigtail catheter (PCN) is placed for preoperative renal access before performing percutaneous nephrolithotomy (PCNL). However, PCN can hamper the passage of the guidewire to the ureter, due to which, access tract can be lost. Therefore, Kumpe Access Catheter (KMP) has been proposed for preoperative renal access before PCNL. In this study, we analyzed the efficacy and safety of KMP for surgical outcomes in modified supine PCNL compared to those in PCN.

MATERIALS AND METHODS

From July 2017 to December 2020, 232 patients underwent modified supine PCNL at a single tertiary center, of which 151 patients were enrolled in this study after excluding patients who underwent bilateral surgery, multiple punctures, or combined operations. Enrolled patients were divided into two groups according to the type of pre-PCNL nephrostomy catheter used: PCN versus KMP. A pre-PCNL nephrostomy catheter was selected based on the radiologist's preference. A single surgeon performed all PCNL procedures. Patient characteristics and surgical outcomes, including stone-free rate, operation time, radiation exposure time (RET), and complications, were compared between the two groups.

RESULTS

Of the 151 patients, 53 underwent PCN placement, and 98 underwent KMP placement for pre-PCNL nephrostomy. Patient baseline characteristics were comparable between the two groups, except for the renal stone type and multiplicity. The operation time, stone-free rate, and complication rate were not significantly different between the two groups; however, RET was significantly shorter in the KMP group.

CONCLUSION

The surgical outcomes of KMP placement were comparable to those of PCN and showed shorter RET during modified supine PCNL. Based on our results, we recommend KMP placement for pre-PCNL nephrostomy, particularly for reducing RET during supine PCNL.

Impact of the implementation of Identification-Situation-Background-Assessment-Recommendation (ISBAR) tool to improve quality and safety measure in a lithotripsy and endourological unit

INTRODUCTION

A lack of professional communication and collaboration may be one of the main causes of medication errors. The objective was to evaluate the results of the implementation of ISBAR as a communication and safety tool in a Lithotripsy and Endourologic Unit of a tertiary public hospital.

METHODS

A total of 457 patients were included in a retrospective study from 2014 to 2019. Patients were divided into two groups: group A (357 patients) in which an endourological procedure was performed before march of 2018 (without the implementation of ISBAR tool) and Group B (100 patients) with the implementation of ISBAR tool. The inclusion criteria were patients accepted for surgical intervention by anaesthesiology Department and operated in the period of the study. The variables analysed included number of procedures, global, intraoperative and postoperative complications rate, urinary infection or sepsis, NPR (FMEA), percentage of suspended surgical patients and hospital stay.

RESULTS

The postoperative complications showed no significant differences between groups, but a trend to diminishing was seen in the complication in the group B. The sepsis reduced its incidence and it was close to significant difference. The operative time was shorter in group B 119,11min (114,63-123,59) vs 115,11min (109,63-121,67) p = 0,3. The reduction in the main postoperative complication (sepsis) explained the lower hospital stay for group B. The severe adverse events detected were reduced completely.

CONCLUSIONS

ISBAR tool was an effective patient safety tool improving quality care. To provide safe patient care and improving quality is indispensable an effective communication flow.

Predictors of Urosepsis Post Percutaneous Nephrolithotomy at King Abdulaziz Medical City, Riyadh

INTRODUCTION

The procedure of percutaneous nephrolithotomy (PCNL) is considered a minimally invasive method for removing stones from the kidneys or ureters. PCNL can cause a wide range of complications, such as urosepsis, a rare but serious complication.

METHODS

A retrospective cohort study of patients who underwent PCNL from the period 2016 to 2022 was conducted at King Abdulaziz Medical City. Data were collected by chart review using the BestCARE system. SPSS version 23 (IBM Corporation, Armonk, NY, USA) was used. Qualitative variables were expressed as percentages and frequencies. The chi-square test was used to compare the qualitative variables. The K-S test was used to check the normality of the data. Quantitative variables were compared between groups using the independent sample t-test and the nonparametric Mann-Whitney test. Fisher's exact test was used to compare categorical variables.

RESULTS

A total of 155 patients were included in this study. The mean age of the participants overall was found to be 49. About 108 (69.7%) of the participants were male. Regarding risk factors for urosepsis, diabetes mellitus was found in 54 (34.8%) of the participants. The incidence of urosepsis following PCNL was found to be 3 (1.9%) of the patients. The most frequently reported indication was found to be unilateral renal stones. The most frequently reported type of stone in the analysis was found to be calcium oxalate in nearly two-thirds 98 (63.2%) of the patients.

CONCLUSION

The incidence of urosepsis among the patients who underwent PCNL was less than 2%. Diabetes mellitus, followed by hypertension, were the most prevalent co-morbidities among the participants. Cefuroxime was the antibiotic of choice when treating patients and following urosepsis.

A mathematical method to estimate angle and distance for percutaneous renal puncture based on computed tomography data: Description and validation

Introduction

Gaining access to the kidney is crucial step in percutaneous nephrolithotomy (PCNL); it has a steep learning curve.

Objective

Describe the mathematical method to predict renal puncture angle and distance based on preoperative computed tomography (CT) measurements. Then evaluating how it correlates with measured values.

Patients and Methods

The study was prospectively designed. After ethical committee approval, the study uses data from preoperative CT to construct a triangle so we can estimate puncture depth and angle. A triangle of three points, the first is point of entry to the pelvicalyceal system (PCS), the second is point on the skin perpendicular to it, and the third where the needle punctures the skin. The needle travel is estimated using the Pythagorean theorem and puncture angle using the inverse sine function. We evaluated 40 punctures in 36 PCNL procedures. After PCS puncture using fluoroscopy-guided triangulation, we measured the needle travel distance and angle to the horizontal plane. Then compared the results with mathematically estimated values.

Results

We targeted posterior lower calyx in 21 (70%) case. The correlation between measured and estimated needle travel distance with Rho coefficient of 0.76 with P < 0.001. The mean difference between the estimated and the measured needle travel was - 0.37 ± 1.2 cm (-2.6-1.6). Measured and estimated angle correlate with Rho coefficient of 0.77 and P < 0.001. The mean difference between the estimated and the measured angle was 2° ± 8° (-21°-16°).

Conclusion

Mathematical estimation of needle depth and angle for gaining access to the kidney correlates well with measured values.

The efficacy and safety of one-stage endoscopy combined with intrarenal surgery (mini-nephrostomy tract) in the prone split-leg position for complex renal calculi

Background

The goal of this study was to determine the safety and efficacy of endoscopic combined intrarenal surgery (ECIRS) performed in the prone split-leg position for the treatment of complex renal stones.

Materials and methods

A mature ECIRS protocol was designed. Retrospective analysis was conducted of medical records between January 2020 and December 2021 of patients with complex renal stones at one center who underwent ECIRS by 2 skilled surgeons using retrograde flexible ureteroscopy and mini-percutaneous nephrolithotomy in the prone split-leg position.

Results

A total of 44 patients were included in this study. Mean stone size was 26.1 ± 12.7 mm, and the number of calyces involved was 4.36 ± 2.09. Mean operative time was 71.1 ± 21.8 minutes. Postoperative decline in hemoglobin was 15.8 ± 9.8 g/L. Seventy-five percent of patients achieved stone-free status. The mean number of residual stones was 2.8 ± 2.3, and the mean residual stone size was 10.30 ± 4.76 mm. Six patients (13.6%) developed postoperative complications, including 4 with fever during the first 2 days postoperatively and 2 patients with transient postoperative pain. No patients developed severe complications.

Conclusions

Endoscopic combined intrarenal surgery in the prone split-leg position can be performed safely by experienced surgeons using retrograde flexible ureteroscopy in conjunction with mini-percutaneous nephrolithotomy as a successful technique for the treatment of complex renal stones.

Efficacy of Ultrasound-Guided Thoracic Paravertebral Block on Postoperative Quality of Recovery in Patients Undergoing Percutaneous Nephrolithotomy: A Randomized Double-Blind Placebo-Controlled Trial

Purpose

This study aimed to examine the effectiveness of ultrasound-guided thoracic paravertebral block on postoperative quality of recovery in patients undergoing percutaneous nephrolithotomy.

Patients and Methods

In this randomized, double-blind, placebo-controlled trial, we enrolled patients scheduled for unilateral percutaneous nephrolithotomy. Patients were randomly allocated to receive thoracic paravertebral block either with 20 mL of 0.5% ropivacaine (PVB group) or an equal volume of saline (control group). The primary outcome was the quality of patient recovery at 24 h postoperatively, assessed using the 15-item Quality of Recovery scale. The secondary outcomes included the area under the curve of pain scores over time, time to first rescue analgesia, and postoperative 24 h morphine consumption.

Results

We analyzed the data of 70 recruited participants. The median Quality of Recovery-15 score at 24 h postoperatively was 127 (interquartile range, 117-133) in the PVB group, which was significantly higher than 114 (interquartile range, 109-122) in the control group, with a median difference of 10 points (95% confidence interval, 5-14; P<0.001). The area under the curve of pain scores over time was lower in patients receiving thoracic PVB than in those receiving saline block (P<0.001). The median time to first rescue analgesia in the PVB group (10.8 h, interquartile range 7.1-22.8 h) was longer than that in the control group (1.9 h, interquartile range 0.5-4.3 h) (P<0.001). Similarly, the median postoperative 24-hour morphine consumption was nearly half as low in the PVB group as in the control group (P<0.001). The occurrence of postoperative nausea and vomiting, and pruritus were significantly higher in the control group (P=0.016 and P=0.023, respectively).

Conclusion

Preoperative ultrasound-guided single injection of thoracic paravertebral block with ropivacaine improved the postoperative quality of recovery and analgesia in patients undergoing percutaneous nephrolithotomy.

Correlation analysis between renal anatomical factors and residual stones after an ultrasound-guided PCNL

Introduction

To predict the factors of residual stones after percutaneous nephrolithotomy (PCNL) by analyzing the characteristics of the renal anatomical structure in intravenous urography, so as to make a reasonable operation plan, reduce the risk of residual stones in PCNL, and improve the stone-free rate (SFR).

Methods

A retrospective study was performed between January 2019 and September 2020 for patients treated with PCNL. According to the results of a kidney ureter bladder review after PCNL, 245 patients were divided into a residual stone group (71 patients, stone size >4 mm) and a stone-free group (174 patients, stone size ≤4 mm). An independent sample t-test was used to analyze the age, the length and width of channel calices, the angle between the channel calices and the involved calices, and the length and width of the involved calices. The gender, the channel types, the number of channels, the degree of hydronephrosis, and the number of involved calices were analyzed by using the chi-square test. A score of p < 0.05 was considered statistically significant. At the same time, logistic regression analysis was carried out to explore the independent influencing factors of the SFR after PCNL.

Results

A total of 71 patients developed residual stones after surgery. The overall residual rate was 29.0%. The width of the channel calices (p = 0.003), the angle between the channel calices and the involved calices (p = 0.007), the width of the involved calices (p < 0.001), the channel types (p = 0.008), and the number of involved calices (p < 0.001) were all significantly correlated with residual stones after PCNL. Logistic regression analysis showed that the width of the channel calices (p = 0.003), the angle between the channel calices and the involved calices (p = 0.012), the width of the involved calices (p < 0.001), the channel types (p = 0.008), and the number of involved calyces (p < 0.001) were all independent influencing factors of the SFR after PCNL.

Conclusion

A larger caliceal neck width and angle can reduce the risk of residual stones. The more calyces that are involved, the higher the risk of residual stones. There was no difference between F16 and F18, but F16 had a higher SFR than F24.

Paravertebral block vs. epidural block for percutaneous nephrolithotomy: A prospective, randomized study

Background

Percutaneous nephrolithotripsy (PCNL) is the main method for urinary calculi. An anesthesia method with little effect on the blood circulation and which does not affect the postoperative activity of a patient is lacking.

Objective

To compare the effects of paravertebral nerve block (PNB) and epidural block (EPB) on quadriceps femoris muscle (QFM) strength in patients after PCNL.

Methods

163 patients were separated into two groups: EPB (81) and PNB (82). Primary outcome parameters were QFM strength and range of motion (RoM) of the knee 1 h, 2 h, 3 h, and 24 h after anesthesia induction (AI). Secondary outcome parameters were: time from AI beginning to first ambulation; time of sensory-plane recovery; amount of additional analgesics given during and after surgery; prevalence of nausea and vomiting; duration of hospital stay (DoHS); mean arterial pressure (MAP), heart rate (HR), and oxygen saturation (SpO₂) before, 0.5 h, and 1 h after AI; visual analog scale (VAS) score 0.5 h, 1 h, 2 h, 3 h and 24 h after AI.

Results

There was no significant difference in QFM strength or knee RoM before or 24 h after AI between the two groups (P > 0.05). The time from AI to first ambulation was shorter (P < 0.05) and the sensory plane took longer to recover (P < 0.05) in the PNB group than in the EPB group. The amount of additional analgesics during surgery was more in the PNB group than in the EPB group (P < 0.05), but there was no significant difference after surgery (P > 0.05). VAS scores were higher in the PNB group than in the EPB group 0.5 after AI (P < 0.05). MAP 1 h after AI was higher in the PNB group than in the EPB group (P < 0.05). There was no significant difference in the prevalence of postoperative nausea and vomiting, DoHS, HR, or SpO₂ at 0.5 h and 1 h after AI between the two groups (P > 0.05).

Conclusions

For patients undergoing PCNL, PNB can meet the need for surgical analgesia while having little effect on QFM strength.

Trial registration

http://www.chictr.org.cn/, identifier ChiCTR2200060606.

Superior calyceal access vs. other calyceal access in percutaneous nephrolithotomy: A systematic review and meta-analysis

Purpose

To evaluate the superior calyceal access’s performance and safety in relation to other calyceal access during percutaneous nephrolithotomy (PCNL).

Methods

The suggested reporting items for systematic reviews and meta-analysis were used to conduct this meta-analysis (PRISMA). To find pertinent studies for this meta-analysis, we searched PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI). Operation time and hospital stay are two secondary outcomes, whereas failed stone clearance and complication events are the two major outcomes. Utilizing Stata 15.0, RevMan 5.3, and R 4.0.2, relative data were extracted and evaluated.

Results

This meta-analysis was based on 16 studies with 8,541 individuals. Pooled results suggested that superior calyceal access could offer fewer failed stone clearance [odds ratio (OR): 0.64, 95% confidence interval (CI), 0.47–0.88, P = 0.006] and lower additional puncture rate (OR: 0.35, 95% CI, 0.24–0.51, P < 0.001) than other calyceal access. No complication difference was found (OR: 1.10, 95% CI, 0.78–1.56, P = 0.57). Superior calyceal access could offer shorter operation time [standard mean difference (SMD): −0.57, 95% CI, −0.98 to −0.15, P = 0.007]. No hospital stay difference was found (SMD: 0.07, 95% CI, −0.09 to 0.22, P = 0.38). Large heterogeneity was detected in stone clearance comparison (I²= 71%, P < 0.001) and operation time (I²= 97%, P < 0.001). The stone clearance comparison also identified significant publication bias (P = 0.026). These defects weaken the credibility of the results.

Conclusion

Superior calyceal access in PCNL may result in a higher stone clearance rate, a lower rate of subsequent punctures, and a faster operation duration with no increase in postoperative complications or hospital stay for kidney stone patients, despite the significant heterogeneity and publication bias. By conducting bigger randomized controlled studies, this discovery still has to be confirmed.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The treatment option for calyceal diverticulum stones: flexible ureteroscopy lithotripsy (FURL) or all-seeing needle-assisted percutaneous nephrolithotomy (PCNL)?

The purpose of this study was to investigate the effectiveness and safety of flexible ureteroscopy lithotripsy (FURL) and all-seeing needle-assisted percutaneous nephrolithotomy (PCNL) for the treatment of calyceal diverticula (CD) stones. From June 2012 to November 2020, 24 patients, including 14 females and 10 males, with an average age of 45.6 ± 17.4 years were retrospectively reviewed in this study. Among these patients, 14 were treated with FURL, and 10 underwent all-seeing needle-assisted PCNL. The demographic data, perioperative parameters and complications, as well as follow-up data, were recorded. In the FURL group, the ostium of CD was not identified in two patients, and these patients were finally treated with all-seeing needle-assisted PCNL. The stone clearance rate (SCR) was 64.3%, and the mean blood loss was 0.9 ± 0.8 g/dL. The average operation time was 57.5 ± 17.4 min, and the mean hospital stay was 3.5 ± 1.4 days. A complete resolution of CD was observed in five (41.7%) patients over the average follow-up of 10.8 months. In terms of the all-seeing needle-assisted PCNL, the average operation time was 83.5 ± 32.4 min, and the mean hospital stay was 4.38 ± 2.25 days. The SCR reached 91.7%, and the blood loss was 1.7 ± 1.1 g/dL. Nine patients (75%) were observed to have complete CD resolution over an average of 12.2 months of follow-up. All complications were grade I and II in both the groups. CD stones can be treated minimally invasive and effectively by FURL and PCNL. The effect of FURL greatly depends on the location and anatomy of the diverticula. PCNL is more efficient, and its safety was improved with the help of the all-seeing needle assistance.

Comparison of renal parenchymal trauma after standard, mini and ultra-mini percutaneous tract dilation in porcine models

OBJECTIVE

To evaluate whether reducing tract dilation diameter in PCNL (percutaneous nephrolithotomy) procedures results in minimizing of renal trauma of the percutaneous tract.

METHODS

A percutaneous renal access tract was established bilaterally to 11 pigs. Two pigs were euthanized immediately after the experiment, while nine pigs were sacrificed 1 month later. The percutaneous accesses were dilated up to 30Fr, 22Fr or 12Fr. The animals underwent a contrast-enhanced computer tomography immediately after the procedure and 30 days later. DMSA-scintigraphy with SPECT-CT was also performed. The kidneys of all animals were harvested for histological evaluation. The volume of scar tissue and the percentage of renal volume replaced by scar tissue were calculated.

RESULTS

Immediate post-procedural CT-scans revealed a significant difference in defect diameter among the three modalities. However, the scar volume calculated on CT-images and histopathology showed a significant difference only when 30Fr dilation was compared to 12Fr dilation. The percentage of scar volume was negligible in all cases, but there was still a statistical difference between 30 and 12Fr dilation. Dilation up to 22Fr revealed no statistical differences compared to the other two modalities. DMSA-scintigraphy showed no scar tissue in any case.

CONCLUSION

Dilation up to 30Fr may cause a significantly larger scar tissue on renal parenchyma compared to 12Fr dilation as it was shown on CT-images and microscopic evaluation, but based on the DMSA/SPECT-CT this difference seems to be insignificant to the renal function. The scar tissue caused by 22Fr dilation seemed to have no significant difference from the other modalities.

Needle-perc-assisted endoscopic surgery for patients with complex renal stones: technique and outcomes

Our aim was to investigate the safety and efficacy of needle-perc-assisted percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS), namely, needle-perc-assisted endoscopic surgery (NAES), in a series of patients with large and/or complex renal stones. From May 2018 to August 2021, a total of 119 patients underwent NAES at our institute. Among them, 94 patients underwent needle-perc-assisted standard PCNL in prone position and 25 underwent needle-perc-assisted RIRS in the Galdakao-modified supine Valdivia position or prone split-leg position. Clinical factors including age, sex, medical history, and stone characteristics were collected. Intraoperative and postoperative outcomes were retrospectively evaluated. The patients' mean age ± standard deviation was 50.3 ± 14.3 years. The mean stone size was 7.6 ± 3.7 and 1.7 ± 0.8 cm for needle-perc-assisted PCNL and RIRS, respectively. Of the 119 patients, 51 had staghorn stones, 16 had solitary kidneys, 17 had a history of ipsilateral renal surgery, and 6 had calyceal diverticular stones. The mean operative time was 83.4 ± 25.9 min for needle-perc-assisted PCNL and 66.3 ± 21.8 min for needle-perc-assisted RIRS. The stone-free rate (SFR) for needle-perc-assisted PCNL was 77.7% after the first treatment and 88.3% after auxiliary treatments. The SFR for needle-perc-assisted RIRS was 88.0% and no auxiliary treatments were carried out in this group. Eleven (11.7%) patients who underwent needle-perc-assisted standard PCNL developed Clavien-Dindo grade I or II complications. Three (12.0%) patients who underwent needle-perc-assisted RIRS developed a fever (grade I). The overall complication rate for NAES was 11.8%, with no urosepsis, angioembolization, or other grade III to V complications. In conclusion, NAES is a safe and effective procedure for one-step complete resolution of large and/or complex renal stones with no additional procedure-related complications.

Laparoscopic assisted mini-ECIRS for ectopic kidney lithiasis: A case report and literature review

INTRODUCTION

Ectopic kidney is a rare anatomic variant with an incidence of about 1 in 900. Renal stones can pose a challenge when a standard approach is not possible. Laparoscopic-assisted endourologic procedure can be a feasible and safe choice.

CASE REPORT AND LITERATURE REVIEW

We present a case of 32 years old man with spastic quadriplegia, megacolon and pelvic kidney undergoing intervention of laparoscopic-assisted Mini ECIRS for staghorn stone of the left pelvic kidney. To the best of our knowledge, only 59 cases are reported in the literature concerning laparoscopically assisted encdourologic treatment which seems a feasible, safe and adaptable technique in selected complex cases.

CONCLUSION

Laparoscopic-assisted mini ECIRS is a viable option for the treatment of ectopic kidney stones. This technique should be considered when anatomical anomalies are encountered, to avoid puncture-related complications.

Transcatheter Angiographic Embolization of Percutaneous Nephrolithotomy-Related Bleeding: A Single-Center Experience

BACKGROUND

To evaluate the clinical characteristics and angiographic features of transcatheter angiographic embolization (TAE) in patients with active bleeding after percutaneous nephrolithotomy (PCNL).

METHODS

Between 2009 and 2018, 45 patients who underwent TAE for hemorrhage control after PCNL were reviewed retrospectively. Patient clinical characteristics and angiographic features of TAE were analyzed.

RESULTS

Of the 3148 patients, 45 (1.4%) patients were treated with TAE after PCNL. The interval from the bleeding episode to TAE was 3 days (1,6). Arterial laceration, arteriovenous fistula, and negative angiographic finding were found in 28 (62.2%), 7 (15.6%), and 10 patients (22.2%). Thirty-five patients (92.1%) achieved primary clinical success. The median-corrected hemoglobin decrease from bleeding episode to TAE was 52 g/L (25.25, 71.00). The median-corrected hemoglobin decrease rate from bleeding episode to TAE was 13.11 g/L·d (5.60, 26.12). The hemoglobin decrease from bleeding episode to TAE was lesser in negative angiographic patients (28.50 (10.75,51.25) g/L VS 53.7 (35.0,73.13) g/L) than in positive angiographic patients (P < 0.05).

CONCLUSIONS

TAE is a safe and effective treatment for post-PCNL bleeding patients. Previous kidney surgery is associated with a higher risk of TAE. Patients with bleeding from multiple negative angiographic findings can be considered for prophylactic embolization.

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).

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.

Assessment of Three-Dimensional Reconstruction in Percutaneous Nephrolithotomy for Complex Renal Calculi Treatment

Introduction: Three-dimensional (3D) reconstruction is a novel imaging technique widely used to improve surgical operations. Some studies have identified its role in Urology for percutaneous nephrolithotomy (PCNL). Objective: To explore the potential benefits of 3D reconstruction technology in PCNL for complex renal calculi treatment. Methods: A retrospective study involving 139 patients with complex kidney stones who underwent PCNL was conducted between September 30, 2018, to September 30, 2019. Group A patients (72) underwent the 3D reconstruction technique before PCNL, while group B (67) did not. The operation time, the duration of the hospital stay, the puncture accuracy, the decrease in hemoglobin concentration, the stone clearance rate, and the postoperative complications were noted and compared between the two groups. Results: The initial stone clearance rates 2 weeks after PCNL were 81.9 and 64.2% in groups A and B, respectively (P < 0.05). The first-time puncture success rates were 87.5 and 47.8 % in groups A and B, respectively (P < 0.05). Group A had a shorter operation time than group B (62 vs. 79 min, P < 0.05). Besides, the 3D reconstructive technique-assisted patients (91.7%) had no or mild complications, compared with (74.6%) group B patients. There was no significant difference in hemoglobin decline and hospital stay between the two groups. Conclusions: The 3D reconstruction technology is an effective adjunct to PCNL in the complex renal calculi treatment.

Approach to nephrostomy tubes in the emergency department

BACKGROUND

Nephrostomy tubes are commonly placed for urinary obstruction, urinary diversion, or future endourologic procedures. While the technical success of nephrostomy tube placement is high, nephrostomy tube complications may occur.

OBJECTIVE OF REVIEW

Limited literature exists regarding the complication of nephrostomy tubes and their approach in the emergency department. This review summarizes the existing literature and provides a framework for emergency providers regarding the evaluation and management of nephrostomy tube complications.

DISCUSSION

Nephrostomy tube failure, caused by kinking, dislodgment, or migration can manifest with obstructive signs and symptoms. In well appearing patients, asymptomatic bacteriuria is common and should not be treated. However, in the presence of infectious symptoms, patients should be treated similarly to complicated cystitis or pyelonephritis. While gross hematuria is common following catheter placement, prolonged hematuria, or the return of hematuria after previous resolution should trigger investigation for hematoma formation or a delayed presentation of an intraoperative vascular injury. Finally, clinicians should obtain laboratory testing, advanced imaging, and specialty consultation if serious complications are suspected.

CONCLUSION

This narrative review highlights general nephrostomy tube care, minor complications, and troubleshooting in the emergency department. The majority of these minor complications can be managed at the bedside without specialty consultation. However, in patients with more serious complications including dislodgement, obstruction, infection, bleeding, and pleural injury, laboratory assessment and advanced imaging to include ultrasound and computed tomography with specialty consultation are essential in the patient's evaluation and management, particularly in cases of immune compromise and worsening renal function.

Is it necessary to have a guidewire down through the ureter during mini percutaneous nephrolithotomy? Single-centre experience with 1052 cases

OBJECTIVES

In this study, it is aimed to identify the rate of successful placement of a guidewire down through the ureter during PNL and to compare the outcomes of different locations of guidewires in the collecting system following renal puncture in terms of success and complications rates.

PATIENTS AND METHODS

Data of 1052 patients who underwent miniPNL in our institution between January 2014 and November 2020 were analysed. Patients were divided into three groups. Group I consisted of patients with the guidewire coiled within the punctured calyx, group II consisted of patients with the guidewire reaching the renal pelvis and group III consisted of patients with the guidewire passed down through the ureter. The groups were compared for successful tract creation and complication rates.

RESULTS

There were 303 (28.8%) patients in group I, 330 (31.4%) patients in group II and 419 (39.8%) patients in group III. Successful tract dilation at the first attempt was established in 298 (94.7%) patients in group I, 328 (99.4%) patients in group II and in all of the 419 (100%) patients in group III. Successful tract creation was established in a second attempt in all of the patients failed in the first attempt. The groups were similar for stone-free and complication rates.

CONCLUSIONS

Placement of guidewire down through the ureter could not be established in more than 60% of the cases. Location of guidewire prior to dilation did not affect the outcomes. Therefore, we suggest to proceed with tract creation even when the guidewire coils within the punctured calyx.

Effects of Transcutaneous Electrical Acupoint Stimulation on Systemic Inflammatory Response Syndrome of Patients after Percutaneous Nephrolithotomy: A Randomized Controlled Trial

Purpose

Transcutaneous electrical acupoint stimulation (TEAS) is widely used. However, no study evaluated TEAS on systemic inflammatory response syndrome (SIRS) of patients after percutaneous nephrolithotomy (PCNL). The study was to evaluate TEAS on SIRS of patients after PCNL.

Methods

67 patients were enrolled and divided into group TEAS and group sham TEAS. Data were collected from 60 participants finally. In the study, TEAS or sham TEAS on bilateral Shenshu (BL23), Yinlingquan (SP9), Hegu (LI4), and Neiguan (PC6) was performed continuously throughout the procedure. The primary outcome included the incidence of systemic inflammatory response syndrome (SIRS) within 48 h after surgery. The secondary outcomes included the serum levels of inflammatory cytokines, hemodynamics changes, complications, and hospital stay after surgery. The serum levels of tumor necrosis factor- (TNF-) α and interleukin- (IL-) 6, mean arterial pressure (MAP), and heart rate (HR) at 30 min before anesthesia (T₀), the time after surgery (T₁), 24 h postoperation (T₂), and 48 h postoperation (T₃) were recorded. The consumption of analgesic during surgery was also recorded, as well as the complications and duration of hospital stay after PCNL.

Results

The incidence of SIRS in group TEAS was lower than group sham TEAS (30% vs. 6.67%, p=0.023). Compared with the sham TEAS group, both levels of TNF-α and IL-6 at T₁, T₂, and T₃ were lower in the TEAS group (p < 0.05). The levels of MAP and HR in sham TEAS at T₁, T₂, and T₃ were markedly higher than that in the TEAS group (p < 0.05). The total consumption of propofol and remifentanil during surgery in group TEAS was lower than that in the sham TEAS group. The incidence of hypotension, hypertension, emergence agitation, and postoperative nausea and vomiting (PONV) was also lower in group TEAS after PCNL (p < 0.05).

Conclusions

TEAS could effectively reduce the incidence of SIRS and inflammatory cytokines for patients who underwent PCNL. In addition, TEAS helped to maintain the hemodynamic stability and cut down the consumption of analgesics during PCNL, reducing the complications after PCNL.

Predictive Model for Systemic Infection After Percutaneous Nephrolithotomy and Related Factors Analysis

Objectives: To investigate the factors associated with systemic infection after percutaneous nephrolithotomy (PCNL) and establish a predictive model to provide theoretical basis for the prevention of systemic inflammatory response syndrome (SIRS) and urosepsis correlate to percutaneous nephrostomy.

Methods: Patients received PCNL between January 2016 and December 2020 were retrospectively enrolled. All patients were categorized into groups according to postoperative SIRS and urosepsis status. Single factor analysis and multivariate logistic regression analysis were performed to determine the predictive factors of SIRS and urosepsis after PCNL. The nomograms were generated using the predictors respectively and the discriminative ability of was assessed by analyses of receiver operating characteristic curves (ROC curves).

Results: A total of 758 PCNL patients were enrolled in this study, including 97 (12.8%) patients with SIRS and 42 (5.5%) patients with urosepsis. Multivariate logistic regression analysis suggested that there were 5 factors related to SIRS, followed by preoperative neutrophil to lymphocyte ratio (NLR) (odds ratio, OR = 1.721, 95% confidence interval, CI [1.116–2.653], p = 0.014), S.T.O.N.E. score (OR = 1.902, 95% CI [1.473–2.457], p < 0.001), female gender (OR = 2.545, 95% CI [1.563–4.144], p < 0.001), diabetes history (OR = 1.987, 95% CI [1.051–3.755], p = 0.035), positive urine culture (OR = 3.184, 95% CI [1.697–5.974], p < 0.001). And there were four factors related to urosepsis, followed by preoperative NLR (OR = 1.604, 95% CI [1.135–2.266], p = 0.007), S.T.O.N.E. score (OR = 1.455, 95% CI [1.064–1.988], p = 0.019), female gender (OR = 2.08, 95% CI [1.063–4.07], p = 0.032), positive urine culture (OR = 2.827, 95% CI [1.266–6.313], p = 0.011). A nomogram prediction model was established to calculate the cumulative probability of SIRS and urosepsis after PCNL and displayed favorable fitting by Hosmer–Lemeshow test (p = 0.953, p = 0.872). The area under the ROC curve was 0.784 (SIRS) and 0.772 (urosepsis) respectively.

Conclusion: Higher preoperative NLR, higher S.T.O.N.E. score, female gender, and positive urine culture are the most significant predictors of SIRS and urosepsis. Diabetes history is the predictor of SIRS. These data will help identify high-risk individuals and facilitate early detection of SIRS and urosepsis post-PCNL.

Double-sheath vacuum suction versus vacuum-assisted sheath minimally invasive percutaneous nephrolithotomy for management of large renal stones: single-center experience

PURPOSE

To compare double-sheath vacuum suction minimally invasive percutaneous nephrolithotomy (DS-mini-PCNL) with vacuum-assisted mini-PCNL (VS-mini-PCNL) and to better define the potential benefits of DS-mini-PCNL.

METHODS

Between July 2019 and May 2020, 117 patients with large radiopaque renal stones underwent mini-PCNL. Of these, 63 underwent DS-mini-PCNL and 54 underwent VS-mini-PCNL. For VS-mini-PCNL, a F20 Y-shaped sheath was used and the oblique arm of the sheath was connected to the vacuum suction. For DS-mini-PCNL, the oblique arm of a F20 Y-shaped sheath (the outer sheath) and a F16 Y-shaped sheath (the inner sheath) was connected to the perfusion inflow and the vacuum suction, respectively. A 550-μm holmium-YAG laser was used for stone fragmentation.

RESULTS

Compared with VS-mini-PCNL group, DS-mini-PCNL group had significantly shorter operative time (35.78 ± 7.77 min vs. 44.56 ± 13.19 min; P = 0.000) and significantly lower fever rate (1.6% vs. 11.1%; P = 0.048). It was not significantly different between the two groups despite the higher initial stone-free rate seen for DS-mini-PCNL group relative to VS-mini-PCNL group (87.7% vs. 81.5%, P = 0.346). Auxiliary procedure rates were 4.8% (three patients) in DS-mini-PCNL group and 16.7% (nine patients) in VS-mini-PCNL group, with a significant difference (P = 0.034). The difference in the final stone-free rate between the two groups was rendered insignificant (93.8% vs. 89.1%, P = 0.510).

CONCLUSIONS

DS-mini-PCNL is a safe and effective modality for large renal stones, which could increase the efficiency of stone extraction and decrease infectious complications compared with VS-mini-PCNL.

Urinary System Iatrogenic Injuries: Problem Review

INTRODUCTION

From May to December 2019, a literature review of the urinary system iatrogenic injury problem was performed. The most cited, representative articles in PubMed, Scopus, and WoS databases dedicated to this problem were selected. Urinary system iatrogenic injuries include ureter, bladder, urethra, and kidney traumas. It is widely thought that the main causes of such injuries are urological, obstetric, gynecological, and surgical operations on the retroperitoneal space, pelvis, or perineum.

METHODS

The purpose of the study is to describe all aspects of the iatrogenic injure problem, under the established scheme and for each of the most damaged organs: the urethra, bladder, kidney, and ureter. The treatment of confirmed iatrogenic injuries largely depends on the period of its detection. Modern medical procedures provide conservative or minimally invasive treatment. An untimely diagnosis worsens the treatment prognosis. "Overlooked" urinary system trauma is a serious threat to society and a particular patient. Thus, incorrect or traumatic catheterization can lead to infection (RR 95%) and urethral stricture (RR ≥11-36%), and percutaneous puncture nephrostomy can cause the risk of functional renal parenchyma loss (median 5%), urinary congestion (7%), or sepsis (0.6-1.5%).

RESULTS

Lost gain, profits, long-term and expensive, possibly multistage treatment, stress and depression, and the risks of suicide put a heavy financial, moral, and ethical burden on a person and society. Also, iatrogenic injury might have legal consequences.

DISCUSSION/CONCLUSION

Thus, the significant problem of urinary tract iatrogenic injuries is still difficult to solve. There is a need to implement mandatory examining algorithms for patients at risk, as well as the multidisciplinary principle for all pelvic surgery.

Pneumatic Lithotripsy versus Holmium Laser Lithotripsy in Percutaneous Nephrolithotomy for Patients with Guy's Stone Score Grade IV Kidney Stone

BACKGROUND AND OBJECTIVE

The aim of this study was to compare the efficacy and reliability of holmium (Ho:YAG) laser lithotripsy (HLL) and pneumatic lithotripsy (PL) in percutaneous nephrolithotomy (PCNL) in the treatment of patients with Grade IV kidney stones based on Guy's Stone Score.

STUDY DESIGN/MATERIALS AND METHODS

This retrospective study included 103 patients with Grade IV kidney stones out of 440 patients who underwent PCNL through HLL and PL in Second Affiliated Hospital of Shantou University Medical College, China, from January 2016 to December 2018. We analyzed preoperative, intraoperative, and postoperative variables of the patients to evaluate the efficacy and reliability of PCNL procedures.

RESULTS

Patients were categorized as Grade I, II, III, and IV, and the patients of each grade were 85 (19.32%), 39 (8.86%), 213 (48.41%), and 103 (23.41%), respectively. In Grade IV, the total operative time (min) for the PL and HLL groups was 137.7 ± 47.79 and 134.27 ± 53.38, respectively (p = 0.744). The variation in laboratory examination values including ΔHGB (g/L), ΔHCT, ΔPCT, and ΔCr (μmol/L) for PL and HLL groups was 19 ± 11.23/12 ± 15.42 (p = 0.012), 0.057 ± 0.034/0.038 ± 0.045 (0.009), 0.027 ± 0.034/0.026 ± 0.034 (0.702), and 3.07 ± 17.4/20.54 ± 65.93 (0.692), respectively. The postoperative hospitalization day was 8.94 ± 4.2 and 7.73 ± 2.75 (p = 0.015), respectively. As for the stone-free rate (SFR), the SFRs for PL and HLL were 48.15% (n = 39/81) and 59.09% (n = 13/22) (p = 0.363), respectively.

CONCLUSIONS

HLL showed a comparable advantage of not only decreased postoperative hemoglobin and hematocrit but also fewer postoperative hospitalization days. Based on the results of our retrospective study, for those Grade IV kidney stone patients who have a risk of bleeding before PCNL operation, HLL can be a considerable treatment option. Besides, in consideration of reducing human care cost, HLL which showed fewer hospitalization days, would be more welcome by patients.

Study on risk factors, bacterial species, and drug resistance of acute pyelonephritis associated with ureteral stent after percutaneous nephrolithotomy

The purpose of this study is to explore the risk factors, bacterial species, and drug resistance of acute pyelonephritis (AP) associated with ureteral stent after percutaneous nephrolithotomy (PCNL) and to provide reference for clinical intervention. The clinical data of 415 patients with indwelling ureteral stent after PCNL from December 2016 to May 2019 were analyzed retrospectively. The patients were divided into infection group (n = 54) and non-infection group (n = 361) according to whether patients had AP. Patients' clinical data, blood and urine bacterial culture, and drug sensitivity were collected and analyzed. The incidence of AP associated with ureteral stent after PCNL was 13.01% and diabetes mellitus (P = 0.001), postoperative stone residue (P = 0.002), urinary leucocytes ≥ 100/HP (P = 0.018), positive urine culture results (P = 0.001), ureteral stent retention time ≥ 8 weeks (P = 0.004), and high S.T.O.N.E. score (P = 0.014) are independent risk factors for it. Escherichia coli (40.54%, 47.82%), Klebsiella pneumoniae (16.21%, 15.21%), Pseudomonas aeruginosa (10.81%, 4.34%), Enterococcus faecalis (21.6%, 19.56%), and epidermis Staphylococci (10.81%, 13.33%) are the main pathogens in blood and urine. The main sensitive drugs of pathogenic bacteria are imipenem, meropenem, tigecycline, piperacillin/tazobactam, ceftazidime, linezolid, teicoplanin, levofloxacin, vancomycin, tigecycline, etc., while levofloxacin, norfloxacin, penicillin G, first, and second-generation cephalosporins showed a strong drug resistance rate (> 70%). This study found that diabetes, postoperative stone residuals, urinary leukocytes ≧ 100 cells/HP, positive urine culture results, ureteral stent indwelling time ≧ 8 weeks, and high S.T.O.N.E. score were independent of AP associated with ureteral stent after PCNL risk factors and Escherichia coli is the main pathogenic bacteria and shows drug resistance.

The clinical research of 1,470 nm laser in percutaneous nephrolithotomy

Background

Percutaneous nephrolithotomy (PCNL) is the primary method for the treatment of renal calculi. The preservation of the nephrostomy tube after operation brings severe pain to the patients. We use a 1,470 nm semiconductor laser to stop bleeding after the operation, which cannot reserve the nephrostomy tube, fully reflect its safety and effectiveness, and provide a new method for clinical practice.

Methods

Forty-two patients with renal stones who came to our hospital from March 2016 to September 2019 were randomly divided into two groups: laser operation group (20 patients) and traditional operation group (22 patients). The stone removal rate, surgical effect, and postoperative complications were compared between the two groups.

Results

There was no significant difference in the stone clearance rate between the two groups at the 4th week after operation (P>0.05). However, the incidence of postoperative infection, incision pain, and massive bleeding in the laser surgery group were lower than those in the traditional surgery group (P<0.05). However, there was no significant difference in urine extravasation and postoperative hematuria between the two groups (P>0.05). The average postoperative hospital stay in the laser surgery group was shorter than that in the traditional surgery group, and the difference was statistically significant (P<0.05). Simultaneously, there was no significant difference in operation time, intraoperative blood loss, and medical expenses between the two groups (P>0.05).

Conclusions

The 1,470 nm laser is safe, effective, and feasible in PCNL operation, especially in hemostasis of the renal puncture channel, and it is worth popularizing.

Clinical Assessment of Risk Factors for Renal Atrophy After Percutaneous Nephrolithotomy

Background

This study explored the risk factors for renal atrophy after percutaneous nephrolithotomy (PCNL), and provides a reference for clinical prevention of renal atrophy after PCNL.

Material/Methods

According to the inclusion and exclusion criteria, the clinical data of 816 patients who underwent PCNL in our hospital from May 2013 to February 2018 were retrospectively collected. Depending on whether the patient had kidney atrophy, they were divided into a renal atrophy group and a non-renal atrophy group. We collected and analyzed data on patient sex, age, kidney location, duration of disease, stone size, hydronephrosis, renal calculus position (renal ureteral junction or multiple pyelonephritis-associated stones), operation time, intraoperative blood loss, perfusion pressure, and pyonephrosis. The indicators with statistically significant differences were selected and multivariate logistic regression analysis was carried out to determine the risk factors for renal atrophy.

Results

Among 816 patients, 49 had renal atrophy and the incidence rate was 6.01%. Univariate analysis and multivariate logistic regression analysis showed that independent risk factors for renal atrophy after PCNL were: duration of the disease longer than 12 months (OR=4.216, P=0.003, 95% CI: 1.714, 7.354), perfusion pressure >30 mmHg (OR=3.895, P=0.001, 95% CI: 1.685, 8.912), moderate and severe hydronephrosis (OR=5.122, P<0.001, 95% CI: 1.847, 9.863), stones located at the junction of the renal pelvis (OR=3.787, P=0.001, 95% CI: 1.462, 7.654), stones located in multiple calyces (OR=4.531, P=0.014, 95% CI: 1.764, 8.196), and pyonephrosis (OR=10.143, P<0.001, 95% CI: 2.214, 16.248).

Conclusions

The main risk factors for renal atrophy after PCNL are: course of disease more than 12 months, moderate and severe hydronephrosis, pyonephrosis, multiple calyceal stones, stones at the junction of the renal pelvis, and intraoperative high perfusion pressure.

Comparing different kidney stone scoring systems for predicting percutaneous nephrolithotomy outcomes: A multicenter retrospective cohort study

OBJECTIVE

To compare the predictive performance of five previously described scoring systems (i.e., S.T.O.N.E., Guy's, Clinical Research Office of the Endourological Society (CROES), the Seoul National University Renal Stone Complexity (S-RESC) and the new Stone Kidney Size (SKS) score) for postoperative outcomes regarding stone-free rate (SFR) and complications in adult patients.

METHODS

Data from 349 patients who underwent percutaneous nephrolithotomy (PCNL) in three urology departments were analyzed. SKS, S.T.O.N.E., S-ReSC, CROES and Guy's nephrolithometry scoring systems were used to retrospectively calculate predictions for each patient. Univariate and multivariate analyses were performed to evaluate factors associated with SFR and complication rates. Receiver operating characteristic (ROC) curves were generated and areas under curves (AUC) were compared to identify the method with the highest predictive value.

RESULTS

Median SKS, S.T.O.N.E., S-ReSC, CROES and Guy's scores were 4, 7, 3, 170.8 and 2, respectively. Overall, SFR was 67.0% (234/349) with a complications rate of 36.7% (128/349). AUCs of each method for predicting stone-free status, highlighted reasonable predictive capabilities with 0.709, 0.806, 0 0.869, 0.207, and 0.735, respectively; however, the S-ReSC scoring system had the best discriminative performance. According to multivariate logistic regression and AUC results, none were effectively capable of predicting complications.

CONCLUSIONS

All scoring systems correlated significantly with stone-free status; although, S-ReSC appears to have the greatest predictive ability. This method is also relatively easy to implement and highly reproducible. However, none of the methods analyzed are able to accurately predict postoperative complications.

Renal pelvis urine Gram stain as a traditional, but new marker in predicting postoperative fever and stone culture positivity in percutaneous nephrolithotomy: an observational, prospective, non-randomized cohort study

PURPOSE

The aim of this study was to evaluate the diagnostic value of renal pelvis urine Gram staining (RPUGS) in predicting postoperative fever and renal stone culture (RSC) positivity in percutaneous nephrolithotomy (PCNL).

METHODS

Totally 141 consecutive patients undergoing PCNL for renal stone were included between January 2018 and December 2019. The RPUGS and renal pelvis urine culture (RPUC) were performed using urine sample from renal collecting system, while RSC was performed using stone fragments. Patients were divided into two groups as Group 1 (n = 119) without postoperative fever (< 38 °C) and Group 2 (n = 22) with postoperative fever (≥ 38 °C). Stone culture and Gram staining models were created for predicting postoperative fever using constant covariates of the presence of residual stone, hydronephrosis, and stone burden.

RESULTS

A significantly higher number of patients in Group 2 had RPUGS, RSC, and RPUC positivity (p < 0.001, for each). The sensitivity, specificity, positive predictive value, and negative predictive value of RPUGS in predicting postoperative fever were 72.7%, 89.9%, 57.1%, and 94.7%, respectively. It was observed that both models had similar predictive values and diagnostic performances. Although RSC and RPUGS had a similar diagnostic value in predicting postoperative fever in univariable analysis, both were found to be independent predictors in multivariable analysis (OR: 10.6, 95% CI 4.07-27.9, p < 0.001 and OR: 15.0, 95% CI 5.4-41.2, p < 0.001, respectively).

CONCLUSIONS

In conclusion, RPUGS is as effective as RSC in predicting fever after PCNL. We recommend RPUGS during PCNL to manage post-PCNL infectious complications.

[Navigation systems for the percutaneous access to the kidney]

BACKGROUND

Percutaneous access to the renal pelvis still remains the most difficult step before nephrolitholapaxy (PCNL). New imaging techniques, such as 3D imaging and various navigation instruments such as electromagnetic, sonographic, CT-controlled and marker-based/iPAD try to simplify this step and reduce complications.

OBJECTIVES

In this review, various new techniques for puncturing the renal collecting system are presented and their advantages and disadvantages are evaluated.

MATERIALS AND METHODS

A systematic literature search was carried out in MEDLINE, whereby only puncture techniques that have already been evaluated in clinical studies were included.

RESULTS

Five different navigation methods for puncturing the renal pelvis before PCNL were found.

CONCLUSION

Intraoperative navigation can be useful when puncturing the collecting system. The combination of ultrasound and fluoroscopy currently remains the gold standard. However, there is still a need for further, primarily clinical, prospective studies to determine which new imaging technology and navigation systems will prevail and thus facilitate the access route to the kidney, especially in the case of special anatomical conditions.

Systematic Review of Current Ultrasound Use in Education and Simulation in the Field of Urology

PURPOSE OF THE REVIEW

We investigate articles in the literature published in the last 5 years (2014-2019) regarding ultrasound education in the specialty of urology.

RECENT FINDINGS

Ultrasound has been touted as the modern day stethoscope. Medical educational governing bodies have encouraged the incorporation of ultrasound in medical school education. However, in this review, we find that there are gaps in educational opportunities and standardization in residency and continuing education for urology practitioners. We have identified several new tools for procedure-specific training published in the last 5 years including MRI fusion prostate biopsy and percutaneous nephrolithotomy. New technology is being fused with traditional ultrasound training to provide procedure-specific ultrasound knowledge. There is a need to incorporate new technology and standards into resident and continuing medical education.

The analgesic efficacy of paravertebral block for percutaneous nephrolithotomy: A meta-analysis of randomized controlled studies

INTRODUCTION

The analgesic efficacy of paravertebral block for percutaneous nephrolithotomy remains controversial. We conduct a systematic review and meta-analysis to explore the analgesic efficacy of paravertebral block for patients with percutaneous nephrolithotomy.

METHODS

We have searched PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases, and randomized controlled trials (RCTs) assessing analgesic efficacy of paravertebral block for percutaneous nephrolithotomy are included in this meta-analysis.

RESULTS

Five RCTs are included in the meta-analysis. Overall, compared with control group after percutaneous nephrolithotomy, paravertebral block is associated with the decrease in analgesic consumption (standard mean difference (Std. MD) = -1.55; 95% confidence interval (CI) = -2.18 to -0.92; P < .00001) and additional analgesics (risk ratio (RR) = 0.17; 95% CI = 0.07 to 0.44; P = .0003), prolonged time to first analgesic requirement (Std. MD = 1.51; 95% CI = 0.26 to 2.76; P = .02). There is no statistical difference of adverse events including nausea or vomiting (RR = 0.51; 95% CI = 0.11 to 2.35; P = .38), or itching (RR = 0.69; 95% CI = 0.26 to 1.81; P = .45) between 2 groups.

CONCLUSIONS

Paravertebral block is effective for pain control after percutaneous nephrolithotomy.