Percutaneous nephrolithotomy in super obese patients (body mass index ≥ 50 kg/m2): overcoming the challenges

Assessment of Factors Responsible for Stone-Free Status After Retrograde Intrarenal Surgery

Aim The study aimed to evaluate the predictive factors that determined stone-free rate (SFR) after retrograde intrarenal surgery (RIRS). Materials and methods This prospective study was conducted on 183 patients undergoing RIRS for renal stones. Patients were categorized into two groups, depending on stone-free status one month following the procedure. SFR was defined as the complete absence of stones or stones <4 mm. The parameters studied included patient demographics, presence of hydronephrosis, presence of preoperative double J-stent, abnormal renal anatomy, and stone characteristics (stone burden, stone number, stone density, stone location, lower pole infundibulopelvic angle, and lower pole renal infundibular length (RIL)). Univariate and multivariate analyses were performed to identify risk factors for residual stones. We assessed the predictive ability of the RIRS score and Resorlu-Unsal stone score (RUSS) for evaluating SFR utilizing receiver operating characteristic (ROC) analysis. Results 183 patients were included in the study with a median age of 51 years. 131 (71.6%) patients were declared stone-free after the procedure. The mean stone size and density were 16.9 SD±7.5 mm and 1038 SD±342 Hounsfield units (HU) respectively. Stone-free patients had lower stone size (14.3 mm vs. 23.6 mm, p<0.01) and stone density (970 HU vs. 1211 HU, p<0.01) compared to non-stone-free patients. Patients with residual stones had steeper lower pole renal infundibulopelvic angle (RIPA) (31.3° vs. 40.7°, p<0.01) and longer RIL (26.6 mm vs. 21.1 mm, p<0.01). Stone multiplicity (p<0.01), lower pole stone location (p<0.01), and renal malformations (p<0.01) were significant influencing factors for residual renal stones after RIRS. Multivariate analysis revealed stone size, stone density (HU), and stone location as independent predictors for SFR after RIRS. Among the scoring systems, the RIRS score had the highest diagnostic accuracy for SFR (area under the curve (AUC): -0.882, 95% CI-0.828-0.936). Conclusion Stone size, stone density (HU), and stone number are important predictors of SFR after RIRS. Lower pole stone location and abnormal renal anatomy play a substantial role in determining SFR after RIRS. In lower pole stones, a long RIL and acute RIPA negatively influence SFR. Additionally, the RIRS score was found to be a better predictor for SFR than the RUSS score.

Has fluoroless endourology (URS and PCNL) come of age? Evidence from a comprehensive literature review

INTRODUCTION

Radiation via the use of imaging is a key tool in management of kidney stones. Simple measures are largely taken by the endourologists to implement the 'As Low As Reasonably Achievable' (ALARA) principle, including the use of fluoroless technique. We performed a scoping literature review to investigate the success and safety of fluoroless ureteroscopy (URS) or percutaneous nephrolithotomy (PCNL) procedures for the treatment of KSD.

METHODS

A literature review was performed searching bibliographic databases PubMed, EMBASE and Cochrane library, and 14 full papers were included in the review in accordance with the PRISMA guidelines.

RESULTS

Of the 2535 total procedures analysed, 823 were fluoroless URS vs. 556 fluoroscopic URS; and 734 fluoroless PCNL vs. 277 fluoroscopic PCNL. The SFR for fluoroless vs. fluoroscopic guided URS was 85.3% and 77%, respectively (p=0.2), while for fluoroless PCNL vs. fluoroscopic group was 83.8% and 84.6%, respectively (p=0.9). The overall Clavien-Dindo I/II and III/IV complications for fluoroless and fluoroscopic guided procedures were 3.1% (n=71) and 8.5% (n=131), and 1.7% (n=23) and 3% (n=47) respectively. Only 5 studies reported a failure of the fluoroscopic approach with a total of 30 (1.3%) failed procedures.

CONCLUSION

The ALARA protocol has been implemented in endourology in numerous ways to protect both patients and healthcare workers during recent years. Fluoroless procedures for treatment of KSD are safe and effective with outcomes comparable to standard procedures and could become the new frontier of endourology in selected cases.

Comparison of Contrast-Enhanced Ultrasound vs Conventional Ultrasound-Guided Percutaneous Nephrolithotomy in Nondilated Collecting System: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: It has been demonstrated that ultrasound (US)-guided renal collecting system access during percutaneous nephrolithotomy (PCNL) is efficient and secure. The puncture success rate fell to 82%, and the total complication rate rose to 15% in kidneys with nondilated collecting systems. Contrast-enhanced ultrasonography (CEUS) has been used in PCNL techniques to address this issue. Methods: We did this meta-analysis following the preferred reporting criteria for systematic reviews and meta-analysis to combine the data of published studies to compare the CEUS-guided PCNL and the standard US-guided PCNL (PRISMA). For relevant literature, we searched PubMed, Embase, Web of Science, CKNI, and the Cochrane Library. The final inclusion date for this meta-analysis was May 1, 2022, and three randomized controlled trials (RCTs) were finally included. RevMan V5.4.1 was used in this work. Standard mean difference (SMD) with a 95% confidence interval (CI) was utilized as the major estimate in the synthesis of continuous data, while odds ratio (OR) with a 95% CI was synthesized as the main estimate in the synthesis of discontinuous data. Results: We found that compared with traditional US-guided PCNL, CEUS-guided PCNL could offer more benefits in terms of single-needle success rate (OR: 3.02, 95% CI: 1.62 to 5.61, p = 0.0005), shorter puncture time (SMD: -1.33, 95% CI: -2.06 to -0.60, p = 0.0004), shorter hospital stays (SMD: -0.37, 95% CI: -0.60 to -0.13, p = 0.002), and a better stone clearance rate (OR: 2.32, 95% CI: 1.15 to 4.68. p = 0.02). Although the PCNL complication rate after surgery was not significantly reduced by the CEUS technique (overall complication: OR = 0.70, 95% CI: 0.37 to 1.30, p = 0.25. Grade 1/2 complication: OR = 0.79, 95% CI: 0.41 to 1.53, p = 0.48; Grade 3/4 complication: OR = 0.44, 95% CI: 0.10 to 1.98, p = 0.28), it could reduce hemoglobin dropping compared with conventional US-guided PCNL (SMD: -0.82, 95% CI: -1.06 to -0.58, p < 0.001). Conclusion: The CEUS-guided PCNL technique is superior to the US-guided PCNL, according to almost all synthesized data. Additional randomized studies are still required.

Percutaneous Nephrolithotripsy in Morbidly Obese Patient: A Case Report

A 50-year old male patient with morbid obesity was admitted for removal of large staghorn calculi and multiple small stones in the left kidney. The patient was managed by Percutaneous Nephrolithotomy (PCNL). Surgery was carried out in prone position and Alken's metal dilators were used for tract dilation. Alken dilators were inserted without any challenges, and the procedure was completed in a shorter span of time than anticipated with total operative time of 2 hours, including the change of positioning from lithotomy to prone. No intra-operative or post-operative complications were encountered. The patient has been followed up for 6 months post-operatively, without any complications or any evidence of stone recurrence.

A prospective, observational study to assess the feasibility and safety of supine percutaneous nephrolithotomy under regional anesthesia for obese patients with a body mass index ≥30

Introduction

Besides being a risk factor for urolithiasis, obesity is a challenge in the treatment of urolithiasis from the perspective of both the surgeon and the anesthetist. In this study, we tried to assess the feasibility and safety of supine percutaneous nephrolithotomy (PCNL) under regional anesthesia in obese patients with a body mass index (BMI) ≥30.

Methods

This was a prospective observational study and included 51 obese patients (BMI ≥30 kg/m²) with renal stones planned for PCNL. All patients underwent supine PCNL under regional anesthesia with the standard technique. A decision for totally tubeless or a tubeless PCNL was made at the end of the procedure and the intraoperative and postoperative data were recorded. All patients underwent computed tomography (CT) imaging at 1 month after surgery to assess the stone-free status and the need for additional treatment.

Results

The mean age of the patients was 53.2 ± 8.09 years, and the mean BMI was 34.4 ± 2.369 kg/m². The mean operative time was 73.3 ± 26.2 min, the mean hospital stay was 58.3 ± 22.1 h, and the mean postoperative Visual Analog Score (VAS) for pain was 3.8 ± 1.4. The stone-free rate was 68.6% on the follow-up CT performed after 1 month, and 31.4% of the patients had significant residual fragments which required re-treatment either by retrograde intrarenal surgery (RIRS) in 19.6% (either as primary RIRS for the residual calculi in one patient [1.9%] or as RIRS for post shock wave lithotripsy (SWL) or alkalinization failure in 9 patients), SWL in 21.6%, or urine alkalinization in 7.8%.

Conclusion

Supine PCNL under regional anesthesia, in this subgroup of obese patients, was found to be feasible and safe with satisfactory stone-free rates and minimal postoperative pain.

Does body mass index impact the efficacy and complication rate of mini-percutaneous nephrolithotomy?

Aim:

This was a retrospective cohort study exploring the efficacy of mini-percutaneous nephrolithotomy in obese patients and whether stone clearance, complication rate and length of stay is impacted by an increasing body mass index.

Method:

Data was collected retrospectively for all mini-percutaneous nephrolithotomies performed at a single centre over a 21-month period commencing March 2017. The primary outcomes included length of stay, stone clearance rates and complications.

Results:

Fifty-eight percutaneous nephrolithotomies were undertaken during the study period and of these cases 81% of patients had a body mass index of 25 or greater. The stone clearance rate was 83%. However, severely obese patients were noted to have a lower stone clearance rate. No complications occurred in the normal body mass index cohort. However, there was no difference in the complication rate for the remaining groups. Post-operative stay was approximately 3 days.

Conclusion:

This study demonstrates that supine mini-percutaneous nephrolithotomies are a safe option in obese patients with no increased risk of serious complication. Whilst stone clearance rates were lower in the severely obese category, clearance was complete in the majority of cases.

Level of evidence:

3

Development and content validation of the percutaneous nephrolithotomy assessment score

OBJECTIVES

To develop and content validate a percutaneous nephrolithotomy assessment score, taking into consideration the procedure-specific risks.

METHODS

This prospective international study utilized the Healthcare Failure Mode and Effect Analysis to systematically outline percutaneous nephrolithotomy and failure modes for each step. A total of 25 h was spent observing percutaneous nephrolithotomy carried out by six expert surgeons. Hazard analysis scoring was carried out by 11 experts. It was determined if the steps were single point weaknesses. Single point weaknesses and those assigned a hazard score ≥4 were included in the percutaneous nephrolithotomy assessment score. The tool was then content validated by 16 experts from 10 countries.

RESULTS

Application of the Healthcare Failure Mode and Effect Analysis identified 64 failure modes; 37 failure modes had a hazard score ≥4. After adaptations based on expert feedback the final percutaneous nephrolithotomy assessment score was developed containing 10 phases, 21 processes and 47 subprocesses. All participants agreed that the tool contained pertinent procedural steps.

CONCLUSIONS

This study has developed and shown the international content validity of a novel percutaneous nephrolithotomy assessment score. The tool can be utilized in modular operating room training to quantify operator progress, and can be used in conjunction with other modules as part of a complete percutaneous nephrolithotomy curriculum for trainees.

Patient positioning during percutaneous nephrolithotomy: what is the current best practice?

Percutaneous nephrolithotomy (PCNL) is the gold standard procedure for treatment of large stones and complex kidney disorders, but its morbidity remains the highest among stone treatment procedures. In pursuit of minimizing complication rates, surgeons have developed different variations of the classic prone position in which PCNL is usually performed; one among them is supine position. In this study, we review the literature and present all available evidence on different variations in positioning during PCNL, in an effort to identify if there is a position that can minimize the morbidity of this procedure.

Increasing Body Mass Index Steepens the Learning Curve for Ultrasound-guided Percutaneous Nephrolithotomy

OBJECTIVE

To define how the learning curve for success in ultrasound-guided percutaneous nephrolithotomy (PCNL) is impacted by body mass index (BMI). Previous research has shown ultrasound-guided PCNL to be an effective method of nephrolithiasis treatment comparable to fluoroscopy-guided PCNL. A common concern for the ultrasound-guided approach is potential imaging difficulty in the obese patient population.

METHODS

A prospective cohort study of consecutive patients undergoing PCNL with ultrasound guidance for renal tract access was performed. Clinical data collected included success in gaining renal access with ultrasound guidance, patient BMI, and clinical outcomes over time. Nonparametric LOWESS regression modeling was performed in R using locally weighted scatterplot smoother (R version 3.3.3) for gradations of patients by BMI group (<30, 30-40, and >40).

RESULTS

A total of 150 cases were examined. Case number and BMI were evaluated as continuous variables. Multivariate logistic regression revealed that BMI (P = .010; OR 0.93) and case number (P<.001; OR 1.03) were significantly correlated with ultrasound success. Sex, age, hydronephrosis, stone type, puncture location, and stone size did not influence success at obtaining ultrasound-only access in a statistically significant fashion. LOWESS regression modeling of the relationship between case number and renal access success depicts that the curve representative of the BMI >40 group is downward and right-shifted relative to the other two groups.

CONCLUSION

The learning curve for successful ultrasound-guided PCNL is impacted by patient's BMI as well as case number. Increasing BMI makes access more challenging when performing ultrasound-guided PCNL.

Skin to calyx distance is not a predictive factor for miniaturized percutaneous nephrolithotomy outcomes

Objective

To evaluate the predictive value of the distance from skin to calyx (SCD) on the outcome and complication rates of patients undergoing mPNL.

Materials and Methods

Patient’s charts, who had undergone mPNL between June 2012 and June 2015, were analyzed retrospectively. Patients who had a preoperative computerized tomography (CT) were enrolled into the study. Two separateurologists evaluated the CT scans and calculated the SCD defined as the distance between the skin and surface/lateral edge of the calyx, which was the preferred site of entry for percutaneous access. The average value of the two measurements was included inthe final analysis to avoid bias. The mean SCD was 75mm. According to the median SCD value, patients were divided into two groups: group 1 (SCD ≤75) and group 2 (SCD >75).

Results

A total of 140 patients and 130 patients were enrolled in groups 1 and 2, respectively. The mean operation time and the mean fluoroscopy time was significantly longer in group 2 (p:0.004 vs. p:0.021). The rate of blood transfusion was significantly higher in group 1 (6 patients). None of patientsin group 2required blood transfusion (p:0.017). Stone-free status after a single session of mPNL was 67.1% in group 1 and 75.4% in group 2 (p:0.112). After additional procedures, stone-free rates increased to 84.3% and 85.4% in group 1 and group 2, respectively (p:0.802).

Conclusion

Our study demonstrated that longer SCD was not a predictive factor for stone-free rates after mPNL. However, SCD over 75mm was associated with longer operation time and fluoroscopy time with lower rates of transfusion.

Predictability and Practicality of Image-Based Scoring Systems for Patient Assessment and Outcome Stratification During Percutaneous Nephrolithotomy: a Contemporary Update

Preoperative nomograms offer systematic and quantitative methods to assess patient- and stone-related characteristics and their impact on successful treatment and potential risk of complication. Discrepancies in the correlation of perioperative variables to patient outcomes have led to the individual development, validation, and application of four independent scoring systems for the percutaneous nephrolithotomy: Guy's stone score, S.T.O.N.E. nephrolithometry, Clinical Research Office of the Endourology Society nomogram, and Seoul National University Renal Stone Complexity. The optimal nomogram should have high predictive ability, be practically integrated into clinical use, and be widely applicable to urinary stone disease. Herein, we seek to provide a contemporary evaluation of the advantages, disadvantages, and commonalities of each scoring system. While the current data is insufficient to conclude which scoring system is destined to become the gold standard, it is crucial that a nephrolithometric scoring system be incorporated into common practice to improve surgical planning, patient counseling, and outcome assessment.

Obesity and its implications on nononcological urological surgery

PURPOSE OF REVIEW

To review and summarize the current literature of the implications of obesity on nononcological urological surgery. We conducted a comprehensive search of the current literature with emphasis on the published literature in the last 18 months.

RECENT FINDINGS

Over time, obese patients have become a more common encounter in clinical practice. Obesity represents a considerable operative challenge and has been linked to a higher rate of postoperative complications. Data regarding surgery for incontinence are inconsistent. Nevertheless, the success rates in obese women are high, and complication rates are relatively low with comparable results to nonobese women. In renal surgery, percutaneous nephrolithotomy and minipercutaneous nephrolithotomy are feasible, well tolerated, and effective even in obese patients. However, certain precautions and availability of proper instruments are necessary.

SUMMARY

Although randomized clinical data are lacking and the results of many studies are inconsistent, evidence supports the feasibility and safety of different nononcological urological interventions in obese patients. Moreover, the success rates and the overall complication rates seem to be comparable to nonobese patients with some exceptions.

Percutaneous Nephrolithotomy in Immunocompromised Patients: Outcomes from a Matched Case-Control Study

OBJECTIVE

To compare the outcomes of percutaneous nephrolithotomy (PCNL) in immunocompromised patients with those of PCNL in healthy population.

PATIENTS AND METHODS

A matched case-control study was performed from January 2009 through December 2014 using our prospectively collected kidney stone database. Patients with positive serology to human immunodeficiency virus (HIV), hepatitis C (cellular immune dysfunction), and patients on high dose of immunosuppressive drugs for treatment of autoimmune diseases composed the case group. Control group included patients with kidney stones and no other comorbidity. Patients were randomly matched based on Guy's score as a surrogate of case complexity.

RESULTS

Sixty-two patients were enrolled in this study, 21 cases and 42 controls. There were no significant differences in age, gender, and body mass index between groups. Regarding PCNL technique, there were no differences in patient positioning, number of accesses, and operative time. Complication rate was higher in the case group (38.1% vs 14.3%; p = 0.032); however, major complications, defined by Clavien score ≥3, were not statistically different (4.8% vs 2.4%; p = 0.611). There was a tendency of more postoperative urinary tract infection in the case group (19% vs 4.8%; p = 0.069). Mean decrease in hemoglobin level (3.3 vs 2.4 mg/dL; p = 0.037) and blood transfusion rate (23.8% vs 4.8%; p = 0.036) was significantly higher in the case group. Immunocompromised patients had a 2.8-fold increased risk of complications (odds ratio [OR] = 2.0, 95% confidence interval [CI] 1.01, 7.74) and a 5.8-fold increased risk of blood transfusion (OR = 5.8, 95% CI 1.29, 26.55). There were no differences in stone-free rate, nephrostomy tube time, and length of hospital stay.

CONCLUSION

Immunocompromised patients are at higher risk for complications such as bleeding after PCNL.

Percutaneous Nephrolithotomy in the Superobese: A Comparison of Outcomes Based on Body Mass Index

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is considered the gold standard for treatment of large renal calculi. Although several investigators have examined the feasibility and outcomes associated with PCNL in obese patients, these studies have been limited by small sample size, lack of a comparator group, or few patients at body mass index (BMI) extremes. We thus compared outcomes of superobese (BMI >50) patients undergoing PCNL vs both an "overweight" and "ideal" cohort.

METHODS

We used a prospectively maintained database to identify ideal (BMI 18.5-25), overweight (BMI 25.1-49.9), and superobese (BMI ≥50) patients who underwent PCNL. Our primary objective was to compare surgical outcomes between groups measured by the percent of patients who required secondary PCNL. We then compared complication rates, need for transfusion, and length of stay (LOS) using chi-square testing and ANOVA where appropriate.

RESULTS

A total of 1152 patients were identified of which 254 were classified as ideal, 840 as overweight, and 58 as superobese. The overweight cohort had a higher mean age and greater proportion of males, whereas staghorn stones were more common in the superobese group. Comorbid conditions were more commonly observed in the superobese cohort. Otherwise, the groups were similar. Surgical outcomes were comparable with 47.2%, 42.0%, and 38.0% of ideal, overweight, and superobese patients requiring secondary PCNL (p = 0.25) with no difference in complication rates, need for transfusion, or LOS.

CONCLUSION

PCNL can be effectively and safely performed in superobese patients with no difference in surgical outcomes or complications when compared to ideal or overweight patient cohorts.