Percutaneous Nephrolithotomy in Obese Patients: Comparison Between the Prone and Total Supine Position

Impact of Obesity on the Outcomes of Supine Percutaneous Nephrolithotomy: A Propensity Score Analysis

Objectives: The aim of this study was to evaluate whether obesity could influence the success and safety of percutaneous nephrolithotomy (PCNL) performed in the supine position. Patients and Methods: This prospective cohort study included 664 patients who underwent supine PCNL between September 2008 and June 2023. Patients were stratified into two groups: obese (272 patients) and nonobese (392 patients). To minimize bias, a 1:1 matching was performed between the groups based on Guy's stone score, preoperative stone burden, and potential confounding variables. Procedural success was defined as the complete absence of stones on CT performed 3 months postoperatively. Safety was assessed by the incidence of overall, infectious, and hemorrhagic complications, with complications graded using the modified Clavien-Dindo classification. Results: The obese patient group showed a significantly higher prevalence of hypertension, diabetes mellitus, and higher anesthetic risk according to the American Society of Anesthesiologists' classification. However, the complexity of the cases and the surgical technique employed were compared between the two groups. In the univariate analysis, no significant differences were observed in success rates (p = 0.118), overall complications (p = 0.222), hemorrhagic (p = 0.104), or infectious complications (p = 0.326). After matching, a significant reduction in hemorrhagic complications was identified in the obese patient group (odds ratio 0.43; 95% confidence interval: 0.18-0.97; p = 0.027). However, obesity was not associated with an increased likelihood of overall (p = 0.093) or infectious complications (p = 0.869), nor did it affect procedural success (p = 0.219). Conclusions: Obesity should not compromise the success or safety of PCNL when performed in the supine position. On the contrary, it may offer a protective effect against hemorrhagic complications. These findings suggest that supine PCNL is a safe and effective surgical option for obese patients, and obesity should not be regarded as a contraindication when the procedure is otherwise indicated.

Ultrasound-guided percutaneous nephrolithotomy (PCNL) success rates in patients with elevated body mass index: a comparative study

Percutaneous nephrolithotomy (PCNL) is considered gold standard treatment of renal stones larger than 20 mm. Several studies have shown that ultrasound guidance during this procedure is more effective and safer than fluoroscopy. A higher body mass index (BMI) can make ultrasound-guided renal access more difficult and unsuccessful. We present a prospective analysis and comparison of ultrasound-guided PCNL in patients with normal and increased body mass index. We performed a prospective comparison of patients who underwent ultrasound-guided PCNL to remove renal stones by a single surgeon between 2020 and 2022. Patients with BMIs greater than 30 (mean 33.87-obese) were compared to those with BMIs less than 30 (mean 25.69-non-obese). Demographic, perioperative, and follow-up data were collected, analyzed, and included in this study. Total of 98 consecutive patients, with 49 patients in each group were analyzed. No statistically significant differences were observed in terms of stone volume (P = 0.085), stone density (P = 0.5590), location of renal access (P = 0.108), surgery duration (P = 0.38), blood loss (P = 0.54), or laboratory changes after surgery (P = 0.60). 87.76% of obese patients were stone free per CT scan at follow-up, compared to 73.47% of normal-weight patients (P = 0.1238). According to Clavien-Dindo classification, six patients in the non-obese group experienced grade II (10%) and grade III (2%) complications, as opposed to six patients in the obese group with grade I (2%), grade II (6%), and grade III (2%) complications. There was no significant correlation between body mass index and the success or safety of ultrasound-guided PCNL. Although more challenging, a higher BMI should not be an impediment to performing this approach. This method is safe, with no increased incidence of postoperative complications or compromise in stone-free status postoperatively and can diminish or avoid both patient's and medical team's exposure to ionizing radiation.

Effect of Body Mass Index on Outcomes of Percutaneous Nephrolithotomy: A Systematic Review and Meta-Analysis

Objective

The current study aimed to assess the efficacy and safety of percutaneous nephrolithotomy (PCNL) in obese and overweight individuals based on body mass index (BMI).

Methods

We electronically explored the databases of PubMed, CENTRAL, ScienceDirect, Embase, and Google Scholar databases for all types of comparative studies investigating the role of BMI on PCNL outcomes. Only studies defining obesity as >30 kg/m² were included. Efficacy outcomes were stone-free rates and operating time while safety outcomes were complications and length of hospital stay (LOS).

Results

Eighteen studies with 101,363 patients were included. We noted no difference in the stone-free rates after PCNL for morbid obese vs normal BMI patients (OR: 0.78 95% CI, 0.57, 1.08 I²= 7% p = 0.13), overweight vs normal (OR: 1.01 95% CI, 0.89, 1.15 I²= 1% p = 0.83) and obese vs normal patients (OR: 1.00 95% CI, 0.87, 1.16 I²= 0% p = 0.95). PCNL operative time was significantly increased in morbid obese (MD: 9.36 95% CI, 2.85, 15.88 I²= 76% p = 0.005) and obese patients as compared with normal patients (MD: 2.15 95% CI, 1.20, 3.10 I²= 0% p < 0.00001), but not for overweight patients. There was no difference in the odds of complications between morbid obese vs normal (OR: 1.26 95% CI, 0.93, 1.72 I²= 0% p = 0.13), overweight vs normal (OR: 1.11 95% CI, 0.96, 1.28 I²= 0% p = 0.15), and obese vs normal patients (OR: 1.07 95% CI, 0.91, 1.27 I²= 0% p = 0.40). LOS was significantly reduced in obese patients (MD: −0.12 95% CI, −0.20, −0.04 I²= 0% p = 0.004) as compared to normal patients, but not for morbid obese or overweight patients.

Conclusion

PCNL has similar efficacy and safety in morbidly obese, obese, and overweight patients as compared to normal BMI patients with no difference in the stone-free and complication rates. Evidence suggests that operating time is increased in morbidly obese and obese patients and the latter may have shorter LOS.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, identifier: CRD42022313599.

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.

Evaluating outcomes of complete supine percutaneous nephrolithotomy for staghorn vs multiple non-staghorn renal stones: a 10-year study

PURPOSE

To evaluate the outcomes of complete supine percutaneous nephrolithotomy (csPCNL) for staghorn stones and multiple large non-staghorn stones.

METHODS

The records of 886 patients who underwent csPCNL from September 2009 to October 2019 were considered. Out of them, 201 cases met the eligibility criteria and they were divided into three groups: 63 cases of staghorn, 68 cases of multiple medium (20 mm < diameter ≤ 30 mm) non-staghorn and 70 cases of multiple large non-staghorn (> 30 mm) stones. Almost all outcomes and stone-related factors were analyzed.

RESULTS

There was not any significant difference regarding age, body mass index, history of urinary tract infection, transfusion rate, complication rate, pre and post-surgery serum creatinine, hemoglobin drop and total hospital stay between the three groups. Stone free rate was 98.5% in multiple medium group, 97.1% in multiple large group and 84.1% in staghorn group (P = 0.001). The operation duration was significantly shorter for the multiple medium group (P < 0.001) but it was not significantly different between the multiple large non-staghorn and staghorn group.

CONCLUSION

The results demonstrated that almost all outcomes were not significantly different between the three groups (especially between staghorn and larger non-staghorn ones). These findings reveal that surgeons could choose csPCNL for treatment of staghorn stones and multiple large non-staghorn stones and consider staghorn stones as challenging as multiple large (especially diameter > 30 mm) non-staghorn stones.

Percutaneous nephrolithotomy outcomes based on body mass index: A 5-year retrospective study in an Indonesian tertiary hospital

Objectives:

The aim of this study was to evaluate the impact of body mass index (BMI) on percutaneous nephrolithotomy (PCNL) outcomes and complications for nephrolithiasis.

Patients and methods:

Patients with a history of PCNL surgery from 2012 to 2017 in Dr. Soetomo General-Academic Hospital were retrospectively evaluated. Patients were then categorized into four groups: underweight (BMI <18.5 kg/m2), normal (BMI 18.5 to 24.99 kg/m2), overweight (BMI ⩾25–29.9 kg/m2), and obese (BMI ⩾30 kg/m2). The association between BMI, subjects’ characteristics, length of stay, stone-free rate (SFR), and complications were analyzed using one-way analysis of variance (ANOVA) and univariate logistic regression.

Results:

The study included 430 male patients (58%) and 310 female patients (42%). They were classified based on their BMI into underweight ( n = 5, 1%), normal weight ( n = 291, 39%), overweight ( n = 271, 37%), and obese ( n = 173, 23%) groups. The underweight BMI group had a higher average blood loss ( p=0.002) compared to the other groups; however, the univariate logistic regression showed that BMI had no significant effect on SFR ( p=0.491).

Conclusion:

PCNL is safe and feasible to be performed in patients with different BMI as obesity has no impact on the outcomes and complications associated with PCNL.

Level of evidence

3

Prone versus supine percutaneous nephrolithotomy: a systematic review and meta-analysis of current literature

INTRODUCTION

Percutaneous nephrolithotomy (PNL) can be performed either in prone or supine position. This study aimed at gathering together randomized controlled trials (RCTs) comparing efficacy and safety between prone and supine PNL.

EVIDENCE ACQUISITION

Systematic review of literature was conducted using the Scopus, Medline and Web of Science databases. Study selection, data extraction and quality assessment were independently assessed by two authors. Meta-analysis was performed with Review Manager 5.3. Sensitivity analyses were performed to exclude studies with high risk of bias.

EVIDENCE SYNTHESIS

Pooled data from 12 studies including 1290 patients were available for analysis. Only one study was found to have overall low risk of bias. Significantly shorter operative time was found in favor of supine PNL (mean difference 13 minutes, 95% confidence interval [CI]: 3.4-22.7; P<0.01). Stone-free rate (SFR)≥14 days after surgery was significantly higher in prone PNL (odds ratio [OR]=2.15, 95% CI: 1.07-4.34; P=0.03). Significantly higher fever rate was found in prone PNL (OR=1.60, 95% CI: 1.03-2.47; P=0.04). Overall SFR, hospital stay length, complications rate, transfusions rate and blood loss, as well as non-lower calyx puncture rate, puncture attempts and tubeless intervention rate did not differ between prone and supine PNL (P>0.05).

CONCLUSIONS

Efficacy of PNL seems balanced between prone and supine position, with comparable overall SFR and shorter operative time in favor of supine PNL. Safety of PNL appears in favor of supine PNL, with lower fever rate. Because of study heterogeneity and possible risks of outcome bias, results from this study should be interpreted with caution. Altogether, both prone and supine PNL account for appropriate therapy options.

Impact of Obesity on Outcomes of Supine Percutaneous Nephrolithotomy

Objectives: To determine whether obesity has an impact on the outcomes of supine percutaneous nephrolithotomy (PCNL). Patients and Methods: We retrospectively evaluated a prospectively created database of patients who underwent PCNL in the supine position from June 2009 to June 2014. The patients were divided into two groups according to their body mass index (BMI): <30 kg/m² (group 1, nonobese) and ≥30 kg/m² (group 2, obese). Pre, peri, and postoperative data were analyzed. Stone complexity was classified according to Guy's stone score. The primary endpoint was the absence of stone fragments of ≥4 mm on CT scans at postoperative day 1. Complications were graded according to the modified Clavien classification. Results: Of the 401 patients, 307 (76.6%) were nonobese and 94 (23.4%) were obese. Regarding demographic and stone characteristics, group 2 (BMI ≥30 kg/m²) had a higher percentage of female patients (67.3% vs 50.4%, p = 0.002) and a higher mean BMI (34.8 vs 24.5 kg/m², p < 0.001) than group 1. Success rates were not statistically different between the groups (group 1 = 61.8%, group 2 = 51%, p = 0.08). There were no differences in the transfusion rate (group 1 = 2.9%, group 2 = 4.2%, p = NS) or total number of complications greater than Clavien grade 1 (group 1 = 13.6%, group 2 = 13.8%, p = NS). Conclusion: In a retrospective study of 400 patients undergoing PCNL, the outcomes were not different between nonobese and obese patients. To our knowledge, this is the first study evaluating these outcomes for PCNL performed in the supine position. Further multicenter and prospective studies are necessary to verify these findings.

PCNL in COPD patient in the sit position under local infiltration anesthesia case report

Background

Percutaneous nephrolithotomy is traditionally performed in the prone or supine position. We report the first case of percutaneous nephrolithotomy in sit position under local infiltration anesthesia.

Case summary

A 69-year-old male presented with left flank pain. Kidney B ultrasound and computed tomography scan showed multiple left renal calculi and hydronephrosis. He had a long history of chronic obstructive pulmonary disease, with severe ventilatory and cardiac dysfunction, and cannot tolerate the prone or supine position. The patient received the surgery in sit position under local infiltration anesthesia. The operative time was 1 h. The visual analogue scale score during the surgery was 3. The patient had no intraoperative and postoperative complications. The postoperative plain radiography showed no residual stone fragments.

Conclusions

We believe that in high-risk patients who need to undergo PCNL, a combination of sit position and local infiltration anesthesia is an alternative method.

Supine percutaneous nephrolithotomy: tips and tricks

This paper aims to give an exhaustive overview of supine percutaneous nephrolithotomy (PCNL) illustrating some tips and tricks in order to optimize its execution in full safety. Critical review of Pros and cons of supine PCNL is accomplished to allow the urologist to experience the beauty of this position while being ready to overcome its minimal shortcomings.

Prone percutaneous nephrolithotomy: its advantages and our technique for puncture

Percutaneous nephrolithotomy (PCNL) is considered the treatment of choice for large urinary calculi and staghorn lithiasis. The approach for this surgery may be either supine or prone, and different access techniques are described in the literature with the use of ultrasound, fluoroscopy, or both combined. We believe that prone PCNL offers to the urologist key advantages, such as the possibility of puncturing anatomically abnormal urinary tracts, to perform multiple percutaneous tracts in the same kidney, experiencing the vacuum cleaner effect, ease of exploring the upper calyx through the inferior calyx, possibility to perform endoscopic combined intrarenal surgery (ECIRS) and bilateral simultaneous surgery, and to performed over local anesthesia. An adequate training for the endourologist should include both the prone and supine techniques for PCNL and to know which patient can benefit the most from each one.

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.

Effects of body mass index on the outcomes of percutaneous nephrolithotomy

OBJECTIVE

To examine the the effect of body mass index (BMI) on PNL results and complications with a large number of patients.

MATERIALS AND METHODS

A total of 958 patients were included in the study, who underwent percutaneous nephrolithotomy in our clinic between 2008 and 2015. Patients were divided into 2 groups according to their body mass index. Patients with a BMI < 30 kg/m2 were classified as group 1 (n:676) and patients with a BMI ≥ 30 kg/m2 were classified as group 2 (n:282). Achieving stone-free status or having residual stones of ≤ 4 mm were considered as operational success.

RESULTS

The mean age was 47.9 years for group 1 and 48.9 years for group 2 patients. At postoperative first month CT analysis, residual stone was not observed in 466 patients (69%) of group 1 and 20 (72%) patients of group 2. There was no significant difference between the groups in terms of stone-free status (p=0.348). There was no significant difference between two groups complications. Also, there was no difference between the groups for requiring additional intervention (p=0.924). No other complications were observed in the patients.

CONCLUSIONS

BMI does not affect the outcomes of percutaneous nephrolithotomy as well as complication rate.

Prone Versus Supine Percutaneous Nephrolithotomy: What Is Your Position?

PURPOSE OF REVIEW

Percutaneous nephrolithotomy (PCNL) is the gold standard surgical procedure for treating large, complex renal stones. Due to its challenging nature, PCNL has undergone many modifications in surgical technique, instruments, and also in patient positioning. Since the first inception of PCNL, prone position has been traditionally used. However, alternative positions have been proposed and assessed over the years. This is a comprehensive review on the latest developments related to positioning in the practice of PCNL.

RECENT FINDINGS

The prone position and its modifications are the most widely used positions for PCNL, but with the introduction of various supine positions, the optimal position has been up for debate. Recent meta-analysis has shown a superior stone-free rate in the prone position and comparable complication rates to the supine position. The advantage of ease of access to the urethra for simultaneous retrograde techniques in the supine position is also possible with modifications in the prone position such as the split-leg technique. Modern-day PCNL has transformed from an operation traditionally undertaken in the prone position to a procedure in which a prone or supine position may be employed; however, published data have not shown significant superiority of either approach.

Modified supine versus prone percutaneous nephrolithotomy: Surgical outcomes from a tertiary teaching hospital

Purpose

The traditional prone positioning of percutaneous nephrolithotomy (PCNL) is associated with various anesthetic and logistic difficulties. We aimed to compare the surgical outcomes of PCNLs performed using our modified supine position with those performed in the standard prone position.

Materials and Methods

A prospective group of 236 renal units (224 patients) undergoing PCNL were included in this 2 site study: 160 were performed in the modified supine position were compared with 76 undergoing PCNL in the prone position. The outcomes of radiation dose, radiation time, stone free rate, body mass index (BMI), stone size, operative time, length of stay (LOS), in hospital and complications were compared. Chi-square and t-tests were used.

Results

There were no significant differences in mean radiation time, radiation dose or stone size between the modified supine and prone groups. The supine group had a higher mean BMI (31 kg/m² vs. 28 kg/m², p=0.03), shorter mean surgical time (93 minutes vs. 123 minutes, p<0.001), shorter mean LOS (2 days vs. 3 days, p=0.005) and higher stone free rate (70% vs. 50%, p=0.005). There were no differences in septic or bleeding complications but the prone group had a higher rate of overall complications.

Conclusions

Modified supine PCNL has significantly lower operative time, shorter LOS and higher stone-free rate compared with prone in our series, while remaining a safe procedure.

How well tolerated is supine percutaneous nephrolithotomy?

PURPOSE OF REVIEW

Supine percutaneous nephrolithotomy (PCNL) has been described in 1988 and several modifications followed since. Despite claimed benefits, supine PCNL is still neglected by the majority of urologists. Lack of experience and the fear of complications are possible explanations for the resistance to supine positioning. This review evaluates recent literature on the use of supine PCNL, focussing on benefits and safety.

RECENT FINDING

The Clinical Research Office of the Endourological Society Global Study and several (retrospective) reports comment on efficacy and safety of PCNL, differences in techniques, or identify conditions and patient factors for best practice. Anesthesiologic benefits (especially in the high risk, cardiopulmonary compromised, patient) and anatomical advantages are described in supine position theoretically favoring safety of supine PCNL. However, there are no prospective randomized studies conducted to support this assumption. Overall, benefits in efficacy or safety, of one position over the other, are not yet proven.

SUMMARY

Supine PCNL has advantages in selected patients. Ultimately, the decision on position should be made on patient's characteristics and surgeon's preference and experience.

[Flexible ureterorenoscopy in obese patients: results from a large monocenter cohort]

OBJECTIVE

To analyze results and morbidity after flexible ureterorenoscopy (fURS) in patients with a body mass index (BMI)>30 kg/m² and to compare with results obtained in a large cohort of non-obese patients.

METHODS

We conducted a retrospective monocenter study including all fURS for urinary lithiasis performed in our institution between January 2004 and December 2010. During the study period, 497 procedures were performed. Twenty-three had to be excluded because of missing data on BMI. Thus, a total of 474 procedures were included in the final analysis, 93 for obese patients (OP) and 381 for non-obese patients (NOP). Characteristics of the patients, stones and procedures were analyzed. Success was defined as clear imaging (completely stone-free) on renal tomography and ultrasonography.

RESULTS

Mean BMI was 33.5 ± 0.3 in OP vs 23.9 ± 0.1 kg/m² in NOP (P<0.0001). Mean stone size, location, and composition were not significantly different between groups. Technical aspects (operative time, ureteral dilatation, access sheath, monobloc extraction) were also similar in OP and NOP. The immediate (63.5% for OP vs 66.1% in NOP, P=0.62) and follow-up (65.1% for OP vs 71% in NOP, P=0.26) stone-free rate were not significantly different between the groups. For stone size<1cm, SFR raised to 77% in OP vs 83% in NOP (P=0.28). The rate of minor complications Clavien II was similar in OP (7.5%) and NOP (12%). No major complication (Clavien III or IV) was observed.

CONCLUSION

fURS is a safe and efficient option for the management of urinary lithiasis in obese patients.

Is the supine position superior to the prone position for percutaneous nephrolithotomy (PCNL)?

The objective of this study is to update the two previous meta-analyses in order to evaluate the efficacy and safety of percutaneous nephrolithotomy (PCNL) for patients in the prone position versus supine position. An electronic database search of MEDLINE, EMBASE, google scholar, and the Cochrane library was performed up to June, 2013. All studies comparing prone with supine position for PCNL were included. The outcome measures were stone-free rate, operative time, complication and hospital stay. Two randomized controlled trials (RCTs) and 7 non-RCTs, including 6,413 patients (4,956 patients in the prone position group and 1,457 patients in the supine position group), met the inclusion criteria. Meta-analysis of extractable data showed that PCNL in the supine position was associated with a significantly shorter operative time (WMD: 21.7; 95% CI 2.46-40.94; p = 0.03) but lower stone-free rate (OR: 1.36; 95% CI 1.19-1.56; p < 0.0001) than PCNL in the prone position. There was no difference between the two positions regarding hospital stay (WMD = 0.05; 95% CI -0.16-0.25; p = 0.66) and complication rate (OR: 1.1; 95% CI 0.94-1.28; p = 0.24). In conclusion, the present study found different results from the two previous meta-analyses results regarding stone-free rate; PCNL in the supine position had a significantly lower stone-free rate than that in prone position.