Beyond Prone Position in Percutaneous Nephrolithotomy: A Comprehensive Review

Supine versus prone pediatric percutaneous nephrolithotomy: A systematic review and meta-analysis

Percutaneous nephrolithotomy (PCNL) is the treatment of choice for pediatric nephrolithiasis more than 20 mm. Prone position was the preferred position for decades. Recently, supine position has gained more interest. This meta-analysis aims to evaluate the safety and efficacy of PCNL in supine versus prone position in pediatric population. A systematic search of PubMed, Scopus, Web of Science, and Cochrane Library was performed till 28 February 2024. The study included comparative studies comparing both positions in children that were written in English. A total of three randomized studies and three retrospective studies were included with a total number of 290 patients. Cochrane risk-of-bias tool for randomized trials was used for quality assessment, while Newcastle-Ottawa scale was used for non-randomized controlled trials. The meta-analysis was conducted using Review Manager software. Numerical data were analyzed using standardized mean difference (SMD), while the risk ratio was used for analysis of categorical data. Fixed or random effects models were used according to heterogeneity. There were statistically insignificant differences between both groups for stone-free rate (RR 1.08, 95% CI [0.98-1.18], p = 0.11) and overall complications (RR 0.93, 95% CI [0.59-1.47], p = 0.76). Operation time was significantly shorter in supine group (SMD -0.99, 95% CI [-1.67 to -0.30], p = 0.005). Therefore, comparable efficacy and safety outcomes were proved between both supine and prone positions for PCNL in pediatrics.

Prone vs supine percutaneous nephrolithotomy: does position affect renal pelvic pressures?

The purpose of this study was to measure and compare renal pelvic pressure (RPP) between prone and supine percutaneous nephrolithotomy (PCNL) in a benchtop model. Six identical silicone kidney models were placed into anatomically correct prone or supine torsos constructed from patient CT scans in the corresponding positions. A 30-Fr renal access sheath was placed in either the upper, middle, or lower pole calyx for both prone and supine positions. Two 9-mm BegoStones were placed in the respective calyx and RPPs were measured at baseline, irrigating with a rigid nephroscope, and irrigating with a flexible nephroscope. Five trials were conducted for each access in both prone and supine positions. The average baseline RPP in the prone position was significantly higher than the supine position (9.1 vs 2.7 mmHg; p < 0.001). Similarly, the average RPP in prone was significantly higher than supine when using both the rigid and flexible nephroscopes. When comparing RPPs for upper, middle, and lower pole access sites, there was no significant difference in pressures in either prone or supine positions (p > 0.05 for all). Overall, when combining all pressures at baseline and with irrigation, with all access sites and types of scopes, the mean RPP was significantly higher in the prone position compared to the supine position (14.0 vs 3.2 mmHg; p < 0.001). RPPs were significantly higher in the prone position compared to the supine position in all conditions tested. These differences in RPPs between prone and supine PCNL could in part explain the different clinical outcomes, including postoperative fever and stone-free rates.

Calcutta position: A new modified supine decubitus for supine PCNL

INTRODUCTION

PCNL (percutaneous nephrolithotripsy) is considered the gold standard treatment for renal stone more than 2 cm. In today's scenario, supine PCNL is considered equally effective as prone PCNL. The ideal position for supine PCNL is still debatable. We hereby describe our initial experiences of supine PCNL in a novel position.

METHODS AND MATERIALS

This prospective study includes 60 patients who underwent supine PCNL in the 'Calcutta position' in our institute from August 2021 to August 2022. Successful procedure was defined as a complete stone free rate or a clinically insignificant residual stone (<4 mm).

RESULTS

Average Operative room (OR) occupancy time was 130.9 ± 19.63 min. The immediate stone free rate was 84.2%, 71.4% and 37.5% for single, multiple and staghorn calculus respectively. Complications include fever, requirement of blood transfusions and renal colic. The average hospital stay was 83.6 ± 17.42 h. Eight patients (13.3%) required secondary procedures like extracorporeal shock wave lithotripsy (ESWL) or relook PCNL. At 3 months average stone free rates were 92%, 85%, 75% for single, multiple and staghorn calculus respectively. We performed supine PCNL in Calcutta position in obese, kyphoscoliosis, poliomyelitis, autosomal polycystic kidney disease (ADPKD), malrotated kidney and diverticular stone with comparable success.

CONCLUSION

Supine PCNL in Calcutta position is a safe and effective option for nephrolithiasis management. Apart from the inherent advantages of supine PCNL it also has the advantages of better C-Arm and nephroscope manoeuvrability. Supine PCNL in Calcutta position was performed in a variety of scenarios with comparable results.

Feasibility of Simultaneous Bilateral Endoscopic Surgery in Prone Split-Leg Position for Bilateral Upper Urinary Tract Calculi: A Pilot Study

INTRODUCTION

We explored the viability of simultaneous bilateral endoscopic surgery (SBES) in the prone split-leg position for managing bilateral calculi.

METHODS

We retrospectively reviewed 72 patients who underwent SBES, with procedures involving ureteroscopy (URS) and contralateral percutaneous nephrolithotomy (PNL) simultaneously, in prone split-leg position.

RESULTS

Operative times averaged 109.38 ± 30.76 min, with an average hospital stay of 7.79 ± 3.78 days. The bilateral stone-free rate (SFR) was 70.83%, while URS and PNL demonstrated comparable unilateral SFR (83.33% and 79.17%, respectively). Receiver operating characteristics curves for predicting unilateral residual fragments yielded an area under the curve of 0.84 (URS) and 0.81 (PNL) with respective cutoff values of stone diameter of 11.55 mm and 23.52 mm. Fifty-seven (79.17%) and 15 (20.83%) patients encountered grade 0-1/2 complications, with no severe complications (grade 3-5) recorded. No significant changes in blood count or renal function were observed post-SBES.

CONCLUSIONS

SBES in the prone split-leg position is a viable option for managing bilateral upper tract urolithiasis. Larger scale studies are needed to further assess safety and efficacy in various positions.

Supine tubeless upper pole PCNL under spinal anaesthesia: Safety, feasibility and outcomes from a tertiary endourology centre

Objective

Supine Percutaneous Nephrolithotomy (PCNL) is being taken up by many urologists in recent times, but there is a tendency to shift to prone PCNL for upper pole puncture. We analyzed the safety, feasibility and outcomes of upper pole access in Supine Percutaneous Nephrolithotomy (sPCNL).

Materials and methods

A retrospective review of all patients undergoing sPCNL at a tertiary care center was done from January 2021 to December 2022. Data collection was done from the maintained imaging, laboratory and hospital records. All cases with complete data on upper pole access were included. Data analysis was done with Xlstat2021.

Results

50 patients with upper pole access were included (64%, 32 with single access and 36%, 18 with multiple accesses). The mean stone size was 23.88 ± 9.99, mean HU was 1093 ± 232.83, and the mean operative duration was 67.92 ± 34.62. Stone clearance rate was 98.82%, with all procedures performed tubeless.The mean haemoglobin drop was 0.75 ± 0.42 gm/dl with 2 (4%) patients needing a blood transfusion. The overall complication rate was 22% with only 1 Clavien Dindo III complication (1 pleural injury and hydrothorax needing USS guided aspiration) and others being Clavien Dindo I/II complications.

Conclusion

Supine PCNL is a feasible and safe approach for upper pole access. While the procedure can be done tubeless, these procedures must be done in experienced endourology units.

Application of image overlapping in percutaneous nephrolithotomy

OBJECTIVE

To investigate the application of ultrasound and CT image overlap in percutaneous nephrolithotomy (PCNL).

METHODS

A total of 140 patients with complicated kidney stones requiring PCNL were prospectively enrolled, from January 2020 to December 2022. These patients were randomly divided into 2 groups, with 70 patients each in the research group and the control group. All participants underwent dual-source, non-contrast CT scan of both kidneys and pelvis before surgery. Preoperative three-dimensional CT reconstruction and simulated puncture were performed in patients from the research group. The best puncture path was determined through ultrasound and CT image overlap. Puncture guided by regular CT and ultrasound was conducted in patients from the control group. Differences in the surgical outcomes between the two groups were compared.

RESULTS

Compared to the control group, the research group had higher stone clearance rate in stage I PCNL, success rate of one-time puncture, less percutaneous channels, less reduction of hemoglobin and shorter procedure time. Complications in stage I PCNL were comparable in the two groups, and there was no significant change in the final stone clearance rates between the two groups.

CONCLUSION

An optimal puncture channel can be chosen using ultrasound and CT image overlap. PCNL can be achieved with precise puncturing, thus achieving coincidence between imaging and anatomy and reducing the amount of blood loss during stage I of PCNL. It also shortens the procedure time and improves stone clearance rate of PCNL.

Supine Versus Prone Percutaneous Nephrolithotomy (PCNL): A Single Surgeon's Experience

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) is one of the greatest advances in the field of urology and has been considered the gold standard in the treatment of renal calculi of more than 2 cm in size. While both the supine and prone positions offer their unique advantages, it is still being debated which position offers the most in terms of surgical outcomes. We have evaluated the two approaches in terms of operative time, success rate, stone clearance rate, safety, and complications.

METHODS

This prospective cohort study was done in the urology department of a tertiary care center in South India between January 2018 and October 2020. A total of 166 patients, with 83 in supine and 83 in prone positions, were included in the study.

RESULTS

Both groups were matched in terms of age, body mass index, stone size and location, co-morbidities, medications taken, presence of diverticular stone, history of surgery, and baseline creatinine level. Mean operative time and pain scores were noted to be less in supine position as compared to prone. Ease of puncture was superior in supine position. Stone residue was noted to be higher in supine PCNL as well.

CONCLUSION

Supine PCNLs are preferred in high-risk patients while the prone position is preferred in bilateral PCNLs, complex anatomy, or larger stone burden.

Effect of patient positioning on anesthesiologic risk in endourological procedures

Objective

The objective is to compare supine and prone positions in terms of arterial blood gas during lithotripsy endourology procedures in different stages.

Material and Methods

Cases of during lithotripsy endourology procedures in our department from March to September 2020 were included prospectively. The variables registered were body mass index, age, the American Society of Anesthesiologists (ASA) score, diabetes mellitus, positive end-expiratory pressure (PEEP), FiO2, stone size, stone location, procedural type, position, procedure duration, PaO2, SaO2, PaCO2, pH, and dynamic compliance. PaO2, SaO2, PaCO2, pH, and dynamic compliance were recorded at the beginning of the procedure, 5 min later, 15 min later, and at the end of the procedure.

Results

Thirty patients in prone position and 30 in lithotomy position were included in this study. Patients in prone position underwent percutaneous nephrolithotomy, and patients in supine/lithotomy underwent retrograde intrarenal surgery or ureteroscopy. Statistically significant differences were found in PEEP, duration, PaO2 at the beginning, SaO2 at the beginning and at the end of the procedure, PaCO2 at the beginning and at minute 5 and pH at the beginning of the surgery. The saturation PaO2 increased significantly on prone position and was statistically significantly better at the end of the surgery.

Conclusions

Both prone and supine positions were safe regarding anesthesiologic risk and had no clinically relevant differences in terms of individual comparisons in arterial blood gas parameters in static moments of the procedure. Prone position was related to an increase in PaO2 and a drop in PaCO2 gradually from the beginning to the end of the surgery.

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.

An Observational Pilot Study on Supine Percutaneous Nephrolithotomy: Initial Experience at a Single-Centre

Objective To assess the surgical outcome of supine percutaneous nephrolithotomy (PCNL) in patients with co-morbidities. Materials and methods We retrospectively reviewed the data of 15 patients who underwent supine PCNL at our centre from September 2019 to May 2021. Preoperatively, a complete examination of the patients, along with biochemical and radiological investigations, was done. The data, which included patient demographics, comorbidities, complexity of renal calculi, complications, and stone clearance rate, were collected from the patients' medical records. Results Patients aged between 31 and 70 years were included in the study. The mean (SD) BMI was 26.01 (2.31). Twelve patients (80%) were overweight with a BMI of 25.3 to 29.3 kg/m². The most common comorbidities were diabetes (33.3%) and hypertension (26.7%). In our study, six patients were American Society of Anesthesiologists (ASA) grade 3 (40%), followed by grade 2 in five patients (33.3%), grade 4, and grade 1 in two patients (13.3%) each. The Guy's Stone score was one in nine patients (60%) and two in six patients (40%). Complete clearance was achieved in 13 (86.7%) patients. Two patients (13.3%) had a stone clearance of more than 80%. Data analysis showed that 14 patients (93.3%) had no perioperative complications. Postoperative abdominal distension was noted in one patient (6.7%), which was managed conservatively (Clavien-Dindo grade 1). We did not encounter any cases of organ injury following supine PCNL. Postoperatively, none of our patients received blood transfusions. Conclusion Our study shows that supine PCNL is a good surgical option, especially for high-risk patients with good stone clearance and low complication rates.

Position-related anesthesiologic considerations and surgical outcomes of prone percutaneous nephrolithotomy: a review of the current literature

The aim of the current study was to perform a critical review of existing literature and report the potential morbidity of patient positioning during urological surgeries as well as evaluate the surgical outcomes and anesthesiologic benefits and risks of prone percutaneous nephrolithotomy (PCNL). A narrative review of the current literature has been performed. Articles related to position-related injuries and complications under general anesthesia in prone positions were selected, studied, and considered for the current review. We found that under general anesthesia, the prone position improved the oxygenation of patients and increased the elimination of carbon dioxide. A potential risk for position-related anesthesiologic side effects was reported for longer spine surgeries in a prone position. The injuries and position-related side effects were extremely rare following prone PCNL since the mean duration of the procedure was significantly shorter than that of spine surgery. In conclusion, the prone PCNL remains the most often utilized and preferred approach globally with well-established success and complication rates. Clinical outcomes of prone PCNL do not demonstrate an increased rate of anesthesiologic complications compared to the supine approach. Standardization of turnover of the position, and reduction of the operative time warrant a faster and complication-free recovery.

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

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

Mini-Percutaneous Nephrolithotomy With an Endoscopic Surgical Monitoring System for the Management of Renal Stones: A Retrospective Evaluation

Purpose

To compare the outcomes and postoperative quality of life of patients with renal calculi who underwent standard percutaneous nephrolithotomy (sPNL), mini-invasive percutaneous nephrolithotomy (mPNL) or mPNL with an endoscopic surgical monitoring system (ESMS) using a retrospective clinical trial.

Methods

Eighty-six adult patients with renal stones who were treated with sPNL were retrospectively compared to ninety-two patients who were treated with mPNL between July 2014 and December 2017. Next, further studies were retrospectively conducted using a matched paired method. The ninety-two patients treated with mPNL were divided into two groups based on whether the endoscopic surgical monitoring system (ESMS) was used (ESMS-mPNL vs. non-ESMS-mPNL). The ESMS used strain gauge transducers to measure the inflow and outflow of irrigation solution. Bleeding and fluid absorption during endoscopic surgery could be accurately calculated by computer program in ESMS.

Results

The fluoroscopy time, complication rate, stone-free status and clinically insignificant residual fragment (CIRF) rate were not significantly different between the two groups (sPNL vs. mPNL). The mPNL group had a significantly longer operation time than the sPNL group, and the mPNL group exhibited a markedly reduced 12-h postoperative visual analogue pain scale (VAS) score, mean hospitalization time, and return to work time, had slightly reduced haemoglobin loss, and underwent more tubeless operations. Moreover, among the 92 patients who underwent mPNL, the operation time (P = 0.090), complication rate (P = 0.996), stone-free status (P = 0.731), CIRF rates (P = 0.125) and number of tubeless operations (P = 0.760) were not significantly different between the two subgroups (non-ESMS-mPNL vs. ESMS-mPNL); however, the patients in the ESMS-mPNL group had significantly longer irrigation times than those in the non-ESMS-mPNL subgroup, along with marked reductions in irrigation fluid, blood loss, haemoglobin loss, 12 h postoperative VAS score, mean hospitalization time, and return to work time.

Conclusions

mPNL is less painful than sPNL in patients undergoing treatment for 20–40 mm renal stones. Similar stone-free rates were achieved by the two procedures, but mPNL was superior to sPNL in terms of blood loss, discomfort, hospitalization time and return to work time. We think that ESMS-mPNL is less painful for patients and more efficacious than non-ESMS-mPNL, and ESMS-mPNL achieves a stone-free rate that is similar to non-ESMS-mPNL in patients receiving treatment for 20–40 mm kidney stones.

Access and Fluoroscopy Time Difference in Patients Undergoing Prone Percutaneous Nephrolithotomy (PCNL) With Ureteric Catheter Placement in Supine Versus Lithotomy Position

Objective: To compare the operative and fluoroscopy time in two different methods of ureteral stent insertion before prone percutaneous nephrolithotomy (PCNL).

Materials and method: Over 12 months, 124 patients with urolithiasis who went through prone PCNL were included in our study. All the patients had kidney stones and were divided into two groups based on the method of ureteral catheter insertion. This was done with the help of flexible or rigid cystoscopy in to group A and group B, respectively. Both groups had an equal number of patients, i.e., 62. The main outcome variables assessed were access time (from intubation to placement of access sheath) and fluoroscopy time during access.

Results: The categorical variables (age, gender, site of the stone) between the two groups were comparable. The access time in groups A and B were 48±4.30 and 77±10 minutes, respectively. The fluoroscopy times in groups A and B were 52±14.63 and 116±47.77 seconds, respectively. A statistically significant difference (p-value < 0.05) was observed for both the access and fluoroscopy time. None of the patients in either of the groups had a misplaced ureteral catheter requiring repositioning.

Conclusion: Flexible cystoscope-assisted insertion of ureteral catheter prior to PCNL significantly reduces operative time, fluoroscopy time, and consequently radiation exposure during PCNL.

Supine versus prone percutaneous nephrolithotomy for renal calculi: Our experience

Objectives:

To compare operative times, safety, and effectiveness of percutaneous nephrolithotomy in the supine versus the prone position.

Materials and methods:

An observational study of 100 patients was conducted in our institution for 2years from 2018 to 2020 divided into 2 groups: 50 patients underwent modified supine percutaneous nephrolithotomy (PCNL) and 50 patients underwent standard prone PCNL. The inclusion criteria included a renal calculus (calyx or pelvis) of any size for which PCNL was indicated and exclusion criteria were patients having contraindications for PCNL such as bleeding disorders, pregnancy, high risk, and co-morbid conditions. The measured data included operative time, number of punctures, stone-free rate, length of hospital stays, and rate of complications.

Results:

The 2 groups were comparable in mean age, male to female ratio, calculus size, number of punctures, residual calculi, and postoperative fever and pain. The mean difference of hemoglobin in the supine PCNL group was 0.37 g/dL whereas in the prone PCNL group it was 0.61 g/dL. The p value was significant at 0.043. The mean time to finish from initial postion was 72.24 minutes in supine PCNL and 88.12 minutes in prone PCNL. The p value was significant (p < 0.001). The mean time before puncture was 20.92 minutes in the supine position and 31.84 minutes in the prone position. The p value was significant (p < 0.001). The mean time from puncture to finish was 51.32 minutes in the supine position and 56.28 minutes in the prone position. The p value was significant (p < 0.001).

Conclusions:

As observed from this study, supine PCNL is associated with a significantly reduced operating time when compared to conventional prone position PCNL procedures. The postoperative complications such as pain and fever were not significantly different. Hence, the supine PCNL is an equally effective modality for treatment of a renal calculus with benefits of simultaneous retrograde access and less operative time compared to the prone PCNL.

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

OBJECTIVES

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

PATIENTS & METHODS

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

RESULTS

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

CONCLUSION

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

The Surgical Technique of Mini Percutaneous Nephrolithotomy

The mini percutaneous nephrolithotomy (mini-PCNL) has become a versatile tool to remove kidney stones >2 cm, lower pole stones >1 cm, renal stones previously unresponsive to shockwave therapy or inaccessible by ureteroscopy (within a caliceal diverticulum), stones within complex urinary tracts (urinary diversions, transplanted kidney, and horseshoe kidneys), and large impacted proximal ureteral stones. After positioning in either the supine or prone position, a cystoscopy is performed to place an open-ended catheter, occlusion balloon, or Accordian device into the collecting system. A foley catheter is placed in the bladder. An ultrasound with a curvilinear probe is used to survey the kidney and guide access into the collecting system with an 18 g percutaneous needle. Once access is obtained, a small 0.5 cm skin incision is made and the percutaneous tract is dilated over a wire. A 16.5F metallic or self-dilating suctioning access sheath is positioned with fluoroscopic guidance. A 12F rigid mini-PCNL nephroscope is used to evaluate the collecting system. Once a calculus is observed, options for stone fragmentation include a lithotripter with ultrasonic and ballistic energy, or laser lithotripsy using holmium or thulium laser fibers. Flexible ureteroscopy can be considered to ensure clearance of the collecting system. A 6F ureteral stent can be placed in either a retrograde or antegrade approach for drainage. The tract is sealed using Surgiflo hemostatic matrix with thrombin. Guidelines for postoperative care and troubleshooting techniques for mini-PCNL are reviewed along with the surgical steps in the accompanying video (Supplementary Video S1). There are few randomized trials comparing mini-PCNL with standard PCNL and ureteroscopy. There is some evidence to suggest a difference in transfusion rates comparing mini- and standard PCNL, as well as differences in stone-free rates when comparing mini-PCNL with ureteroscopy for the treatment of lower pole stones.

Application of S.T.O.N.E. Nephrolithometry Score for Prediction of Stone-Free Status and Complication Rates in Patients Who Underwent Percutaneous Nephrolitotomy for Renal Stone

Background: Renal stone disease is a common disorder in urology practice. Kidney stone has various treatment methods such as extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy (PCNL). In this study, we aimed to determine the value of S.T.O.N.E. nephrolithometry score, which is considered as a new scoring system for predicting residual stone rate and complications in patients undergoing PCNL due to renal calculi. Materials and Methods: A total of 120 patients >18 years old who underwent PCNL were evaluated prospectively. Five parameters available from preoperative noncontrast-enhanced computed tomography were measured: stone size (S), tract length (T), obstruction (O), number of involved calices (N), and essence or stone density (E) and then S.T.O.N.E. nephrolithometry score was calculated. The prediction of the stone-free rates and complication rates of this scoring was evaluated statistically. Results: When the age, gender, body mass index, comorbidities, and American Society of Anesthesiologists scores of the patients were evaluated according to the patients' postoperative stone-free status, no statistical difference was found between the groups. Patients had a stone-free rate of 78%. Patients' mean neuropilitometry score was calculated to be 7.75 S.T.O.N.E. nephrolithometry score statistically significant (P = .001) for prediction of stone-free status. S.T.O.N.E. nephrolithometry score was significantly correlated with operation time, estimated blood loss, duration of fluoroscopy, duration of hospital stay, and number of punctures. Complications were seen in 13 patients. Conclusions: S.T.O.N.E. nephrolithometry score can be used as an objective criterion for predicting the complexity of the PCNL process. In addition, this scoring system is expected to provide more objective preoperative counseling and can provide standardization in academic studies.

Prone versus Barts “flank-free” modified supine percutaneous nephrolithotomy: a match-pair analysis

Background/aim

In this study, we aimed to compare the results of prone and Barts “flank-free” modified supine percutaneous nephrolithotomy (PCNL) operations in our clinic.

Materials and methods

The data from patients that underwent Barts “flank-free” modified supine PCNL (BS-PCNL) (n = 52) between June 2018 and July 2020 and prone PCNL (P-PCNL) (n = 286) between April 2014 and June 2018 were retrospectively evaluated. Of those 286 patients, 104 patients whose sex, age, body mass index, American Society of Anesthesiology score, stone localization, stone size, and hydronephrosis matched the BS-PCNL group in a 1:2 ratio were included in the study. The groups were compared in terms of intraoperative outcome, complication rates, and stone-free rates.

Results

The mean age of all patients (58 females, 98 males) included in the study was 41.8 ± 15.2 years, and the mean body mass index (BMI) was 24.7 ± 2.9 kg/m2. The mean operation time was significantly shorter in the BS-PCNL group than in the P-PCNL group (80.2 ± 15.1 min vs. 92.4 ± 22.7 min and p = 0.01). There was no significant difference between the two groups in terms of fluoroscopy time, intraoperative complications, postoperative complications, and stone-free rates.

Conclusion

Our study shows that BS-PCNL is an effective and safe method that significantly reduces the operation time and should be considered as one of the primary treatment options for patients scheduled for PCNL.

FACTORS AFFECTING PATIENT RADIATION EXPOSURE DURING PRONE AND SUPINE PERCUTANEOUS NEPHROLITHOTOMY

Purpose Radiation exposure from fluoroscopy poses risks to patients and surgeons. Percutaneous Nephrolithotomy (PCNL) has traditionally required fluoroscopy, however the use of ultrasound (US) has decreased radiation exposure. US-guidance in supine PCNL may further reduce radiation exposure. In this study we investigate patient and operative factors affecting fluoroscopy time (s), total radiation dose (mGy) and effective radiation dose (ERD) (mSv) in patients undergoing US-guided supine or prone PCNL. Methods: We performed a retrospective study of patients undergoing US-guided PCNL in prone position and supine position. Patients with multiple access tracts, pre-existing renal access or fluoroscopic renal access were excluded. Patient demographic, radiologic and operative data were collected, and compared between the two groups. Results: 99 patients were included: 45 prone (P-PCNL) and 54 supine (S-PCNL). There were no significant demographic differences between the two groups. Operative time, access location, tract length and total radiation dose (mGy) also did not differ. S-PCNL was associated with lower ERD (2.92mSv ± 0.32 vs 5.3mSv ± 0.7, p=0.0014) despite increased fluoroscopy time (86.32s ± 7.7 vs. 51.00s ± 5.1, p=0.004), and was more likely a mini-PCNL (35.2‰ vs 15.9‰, p=0.032). In multivariate analysis, supine PCNL remained associated with reduced ERD compared to prone (p=0.002), whereas BMI (p<0.001) and staghorn calculi (p<0.001) were independently associated with increased ERD.

Classification and standardized reporting of percutaneous nephrolithotomy (PCNL): International Alliance of Urolithiasis (IAU) Consensus Statements

BACKGROUND

The aim of this study was to reach a consensus in the classification and standardized reporting for the different types of PCNLs.

METHODS

The RAND/UCLA appropriateness methodology was used to reach a consensus. Thirty-two statements were formulated reviewing the literature on guidelines and consensus on PCNLs, and included procedure specific details, outcome measurements and a classification for PCNLs. Experts were invited to two rounds of input, the first enabled independent modifications of the proposed statements and provided the option to add statements. The second round facilitated scoring of all statements. Each statement was discussed in the third round to decide which statements to include. Any suggestion or disagreement was debated and discussed to reach a consensual agreement.

RESULTS

Twenty-five recommendations were identified to provide standardized reporting of procedure and outcomes. Consensual scoring above 80% were strongly agreed upon by the panel. The top treatment related outcomes were size of sheath used (99.1%) and position for PCNL (93.5%). The highest ranked Outcome Measures included definition of postoperative hospital length of stay (94.4%) and estimated blood loss (93.5%).

CONCLUSIONS

The consensus statements will be useful to clarify operative technique, in the design of clinical trials and standardized reporting, and presentation of results to compare outcomes of different types of PCNLs.

Frequency of Blood Transfusion in Percutaneous Nephrolithotomy

Introduction

Percutaneous nephrolithotomy (PNL) has replaced open surgery for the treatment of kidney stones due to its less invasive nature. Bleeding still occurs due to renal vascular injuries, dependent upon the access route of the procedure. Several other factors are also related to the increased risk of bleeding. This study aims to find the association between blood transfusion and other factors such as age, gender, body mass index (BMI), size of the stone, operative time, preoperative hemoglobin (Hb) level, stone surface area, hypertension, and diabetes mellitus.

Materials and methods

This was a descriptive cross-sectional study conducted over a period of six months between November 2019 and April 2020 at a tertiary care hospital in Karachi, Pakistan. The sample size of 131 patients was calculated using open-source epidemiological software (Open-Epi). Inclusion criteria included patients from both genders and ages between 26 and 70 years. Patients ≤25 years, having a liver disease or bleeding disorders, or refusing to participate in the study, were excluded. Laboratory data included preoperative routine complete blood count, serum creatinine (normal 0.5-1.5 mg/dL), platelet count, bleeding and coagulation profile, and urine culture. All patients also underwent renal ultrasound scans. Treatment was postponed until a negative urine culture was obtained from patients with a positive urine culture. 

Results

The mean age of the patients was 42.4 ± 15.65 years. One third (29.8%) of the patients were females. The stone size was 850 ± 121.43 mm², the mean operative time of the procedure was 125.76 ± 53.4 minutes, and the mean number of cell packs transfused was 1.10 ± 0.31 units. Blood transfusion was done in 24 (18.3%) of the patients. Gender, diabetes mellitus, stone size, preoperative Hb level, and operative time were significantly related to blood transfusion. 

Conclusions

Increased bleeding risk while performing PNL has been associated with many factors such as operating time, the gender of the patients, and stone size. Therefore, these factors should be controlled for the procedure to decrease the risk of bleeding and the need for blood transfusion. Furthermore, the kidney vasculature should not be compromised while performing the procedure.

Update on Surgical Management of Pediatric Urolithiasis

Urolithiasis has always been a fascinating disease, even more so in children. There are many intriguing facets to this pathology. This article is a nonsystematic review to provide an update on the surgical management of pediatric urolithiasis. It highlights the pros and cons of various minimally invasive surgical options such as extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL), laparoscopy, and robotics. This article also describes the various intracorporeal disintegration technologies available to fragment the stone, including the newer advancements in laser technology. It also emphasizes the cost considerations especially with reference to the emerging economies. Thus, this manuscript guides how to select the least-invasive option for an individual patient, considering age and gender; stone size, location, and composition; and facilities and expertise available.

Observational prospective study for surgical outcome and anesthetic feasibility of tubeless and totally tubeless supine PCNL: A single centre initial experience

OBJECTIVE

To evaluate surgical outcome and spinal anesthetic feasibility of supine percutaneous nephrolithotomy (PCNL) by tubeless and totally tubeless method.

MATERIAL AND METHODS

This observational study included a totally 53 patients. Initial diagnosis of renal stone was based on urinary ultrasonography, kidney, ureter and bladder X-ray, and later confirmed by computed tomography urography. PCNL was done with the patient in Galdakao-modified supine Valdivia position. Nephrostomy was not done using tubeless method, while in totally tubeless method instead of insertion of double j stent, ureteral catheterization was done and the ureter catheter was kept for <24 hours. During postprocedural period, patients were observed for development of fever, perinephric collection, need for blood transfusion and duration of hospital stay.

RESULTS

Patients aged between 14 and 75 years were included in the study. Out of totally 53 patients, supine tubeless PCNL was done in 23 patients while 30 were operated using totally tubeless method. Twenty-nine patients were induced by spinal anesthesia and 24 by general anesthesia. Stone sizes were found to be in the range of 1.4cm to 5.1 cm. Forty-six (86.7%) patients were managed by inferior calyceal puncture. Three patients required double puncture in whom 2 had developed perinephric collection. Complete stone clearance achieved in 49 (92.4%) patients. Four patients developed fever and 2 cases required one unit blood transfusion postoperatively.

CONCLUSION

Tubeless and totally tubeless supine PCNL is technically feasible with good surgical outcomes and can be done under spinal and general anesthesia in properly selected patients.

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

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

Total tubeless ultra-mini supine percutaneous nephrolithotomy: A feasibility study

OBJECTIVE

The ultra-mini percutaneous nephrolithotomy (PCNL) for treating low-volume renal nephrolithiasis is being used as an alternative modality to the conventional PCNL. However its use in the supine position has been scarcely reported.

MATERIAL AND METHODS

Patients who underwent ultra-mini PCNL in the supine position within the time frame of January 2017 to July 2017 were studied. All these patients had this as their first-line treatment. The patients had calculus limited to either a single calyx or just extending to the pelvis and the stone size was less than 2 cm in its maximal dimension. An 8.5 Fr operating nephroscope was used. The patients were positioned in the Galdakao modified Valdivia supine position. The stones were fragmented using Holmium-YAG laser. Various surgical outcomes including duration of the surgery, stone-free rate and any subsequent complications-if any-were analyzed.

RESULTS

The study includes a series of 14 patients with 15 renal units (one patient treated with bilateral renal stone disease). The mean age of the patients was 39.07 years and body mass index was 25.5 kg/m². Intrarenal stone location was as follows: lower calyx, n=8; middle calyx, n=3, upper calyx, n=1, and pelvis, n=3. Median operative time was 52.66 min (range: 40-70) and the stone-free rate was 93.3%. Only one patient had residual fragments and needed subsequent extracorporeal shock wave lithotripsy.

CONCLUSION

Ultra-mini PCNL in supine position with a complete tubeless approach for renal stone disease is a safe method for treating low-volume disease. Studies with a larger cohort may be required to finally validate this technique.

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.

A Complication after Percutaneous Nephrolithotomy: Anesthesia Mumps

Some surgical procedures performed under moderate and sometimes extreme positions expose patients to nonphysiological changes. Especially, the manipulations of a patient in prone and lateral decubitus position might increase complications. Anesthesia mumps has been reported as one of these complications. It has been found to be rare but known entity associated with patients of all age groups and all surgical positions. We herein describe an early noticed acute case of unilateral anesthesia mumps that developed after endotracheal intubation in prone position in a 54-year-old female. Anesthesia mumps may occur in the immediate postoperative period with no suspicious predisposing factor. The reports of such cases would increase the awareness among anesthesiologists and postoperative caregivers regarding this benign complication.

[S2k guidelines on diagnostics, therapy and metaphylaxis of urolithiasis (AWMF 043/025) : Compendium]

Every tenth German citizen will suffer from at least one urinary calculus during the lifetime. The diagnostics, treatment and follow-up treatment of urolithiasis are, therefore, part of the daily routine practice for all urologists in hospitals and private practices as well as in many other disciplines, such as general practitioners, internists, nephrologists and pediatricians. Although the diagnostics and therapy have experienced substantial alterations over the last 10 years, the possibilities of metabolic diagnostics and secondary prevention for patients at risk are, unfortunately and unjustly, in many places very poorly represented. The present S2k guidelines, which for the first time were established in an interdisciplinary consensus process, represent the current practical recommendations and, whenever possible, use tables and algorithms in order to facilitate easy reference in the routine daily work. Last but not least, this greatly simplifies the measures for metaphylaxis.

Upper Calyx Accessibility Through a Lower Calyx Access Is Not Influenced by Morphometric and Clinical Factors in Supine Percutaneous Nephrolithotomy

OBJECTIVE

To assess whether morphometric and clinical parameters influence accessibility to the upper calyx through a lower calyx tract during supine percutaneous nephrolithotomy (SPCNL).

PATIENTS AND METHODS

Data for 114 consecutive SPCNLs performed between June 2014 and March 2016 in an academic medical center were analyzed. Successful approachability was defined as rigid nephroscopic access to the upper calyx introduced through a lower calyx access as attested by direct visualization of the upper calyx papillae and position of the nephroscope on intraoperative pyelography. Demographic, morphometric, and clinical parameters were assessed. Analysis of variance, Fisher's exact, chi-square tests, and univariate and multivariate models were applied.

RESULTS

Successful approach was achieved in 94 (82%) patients. In univariate analyses previous kidney operations (p = 0.03), body weight (p = 0.04), and acute lower calyx access to the upper calyx axis angle (p = 0.01^E-13) correlated with failed access. Multivariate analyses revealed that an acute angle was the sole independent factor for failed access (odds ratio [OR] 1.4, p < 0.05; confidence interval [95% CI] 1.021, 2.035). Limitations include the inability to objectively determine the mobility of the kidney as a co-factor in successful approachability.

CONCLUSIONS

SPCNL offers effective endoscopic accessibility through a lower calyx access. Previous kidney operations and body weight tend to negatively influence this accessibility. An acute angle between the lower calyx and the upper calyx is the single independent factor associated with failed accessibility.

Implementation of supine percutaneous nephrolithotomy: a novel position for an old operation

Introduction

Supine percutaneous nephrolithotomy (PCNL) has become increasingly widespread during the last 2 decades.

The aim of this study was to analyze the transition from prone to mainly supine PCNL in 2 endourologic centers.

Material and methods

We retrospectively analyzed data on 214 consecutive supine PCNLs divided into the first (2011–2013) and last (2014–2016) 3 years of this study. The first 27 cases were also included in a randomized controlled trial (RCT) by comparison with 24 prone PCNLs. We compared the clinical outcome and implementation rate. The surgical team was surveyed for their overall impression of performing supine PCNLs.

Results

The RCT revealed a trend toward shorter operative time (138 vs. 150 minutes), anesthesia time (174 vs. 192 minutes) and hospitalization (2.2 vs. 2.6 days) in the supine PCNL group, without statistical significance and similar stone free rates (SFR) as for the prone PCNL group. Implementation of the supine PCNL reached 96% in 3 years. There was a decrease in operative time (110 vs. 154 minutes; P <0.0001), hospital stay (1.5 vs. 2.1 days; P <0.01), blood transfusion (5% vs. 14%; P <0.05) and rate of ancillary procedures (5% vs. 16%; P <0.05) in the last 3 years of the study. SFR remained stable. Both the surgeons and anesthesiologists expressed their unanimous preference for the supine position over the prone position.

Conclusions

Supine PCNLs are easy to implement without a significant learning curve for an experienced endourologist. They can be employed in complex cases and improve surgeon's ergonomics and anesthesiologist's access to the patient.

Positioning for percutaneous nephrolithotomy

PURPOSE OF THE REVIEW

To highlight the progressive evolution of the issue of patient positioning for percutaneous nephrolithotomy (PNL), explain the history of the prone and supine positions, report respective advantages and drawbacks, critically interpret the past and current literature supporting such arguments, identify the best candidates for each position, and reflect on the future evolution of the two approaches.

RECENT FINDINGS

Positioning for PNL has become a matter of debate during the last decade. The traditional prone PNL position - most widely performed with good success and few complications, and exhibiting essentially no limits except for the treatment of pelvic kidneys - is nowadays flanked mainly by the supine and supine-modified positions, equally effective and probably safer from an anesthesiological point of view. Of course, both approaches have a number of advantages and drawbacks, accurately reported and critically sieved.

SUMMARY

The current challenge for endourologists is to be able to perform PNL in both prone and supine positions to perfectly tailor the procedure on any patient with any stone burden, including increasingly challenging cases and medically high-risk patients, according to the patient's best interest. Intensive training and experience is especially needed for supine PNL, still less popular and underperformed worldwide.

VIDEO ABSTRACT

http://links.lww.com/COU/A8.

Kidney Stones in Several Spinal Abnormalities: A Challenging Treatment

Patients with severe skeletal deformities are a challenging group to treat. A female, white, 35-year-old presented with right kidney stones located in renal pelvis, lower calyx, and upper ureter. She was affected by severe spinal deformity with restrictive respiratory obstruction, caused by kyphoscoliosis. Percutaneous nephrolithotomy in supine position was performed, achieving complete removal of kidney stones. The treatment of renal stones in this patient was complex, so special attention to respiratory function was mandatory; this was a challenging but feasible situation.

Unplanned flexible ureteroscopy during percutaneous nephrolithotomy in the prone position

BACKGROUND

Over time, the prone position has been shown to be effective and safe for performing percutaneous nephrolithotomy. One of its disadvantages, however, is the inability to simultaneously perform an ureteroscopy after positioning the patient, which is feasible in the supine position. Our objective is to demonstrate the feasibility of implementing flexible ureteroscopy with the patient in the prone position.

MATERIAL AND METHODS

We present a case of percutaneous nephrolithotomy of partial staghorn calculi in the prone position during which access to the middle calyx was not possible. It was therefore necessary to conduct flexible ureteroscopy. The 64-year-old female patient had consulted for lumbar pain of 6 months of evolution.

RESULTS

We performed percutaneous nephrolithotomy in the prone position. After extracting calculi from the inner calyx and renal pelvis, access to the fragments located in the middle calyx could not be achieved. Rather than performing a new puncture, we decided to enter in a retrograde manner with a flexible ureteroscope, succeeding in extracting the residual calculi, leaving the patient completely free of calculi.

CONCLUSION

In our case, the implementation of retrograde flexible ureteroscopy was feasible without changing the patient's original position.

Percutaneous Nephrolithotomy in Patients With BMI >50: Single Surgeon Outcomes and Feasibility

OBJECTIVE

To evaluate the use of percutaneous nephrolithotomy (PNL) and technical approach in the super obese population (body mass index [BMI] ≥ 50).

MATERIALS AND METHODS

We performed a retrospective review of 31 consecutive PNL cases with a BMI > 50 from a single surgeon (SYN) from 1995 to 2013. Procedures were performed in the prone position, and upper pole access was used. Operative time, length of hospital stay, stone burden, complication rates, and stone-free rates were measured.

RESULTS

Of the 31 patients who underwent PNL (age 51.2 ± 12; 71% female), the mean BMI was 59.1 ± 6 kg/m(2) (range 50.4-71.7 kg/m(2)). Mean stone burden was 3.8 cm ± 2. The majority of patients (90.3%) had an upper pole puncture site for access with an operative time of 122.1 ± 75 minutes. The technique was similar to non-obese patients; however, there was a need for extra-long instrumentation. The overall stone-free rate was 71%, with utilization of a second-look PNL in 11 cases. The complication rate, Clavien grade 3 or higher, was 9.7% (3 of 31).

CONCLUSION

PNL is technically feasible, safe, and effective in patients with a BMI ≥ 50. The complication rate, length of hospital stay, and stone-free rate with use of second-look PNL in super obese patients are comparable to severely obese patients. Intervention should not be automatically ruled out or delayed based on the patient's BMI alone.

Recent advancement or less invasive treatment of percutaneous nephrolithotomy

Since its initial introduction in 1976, percutaneous nephrolithotomy (PCNL) has been widely performed for the management of large renal stones and currently is recommended for staghorn calculi, kidney stones larger than 2 cm, and shock wave lithotripsy-resistant lower pole stones greater than 1 cm. However, except for open and laparoscopic surgery, PCNL is the most invasive of the minimally invasive stone surgery techniques. Over the years, technical and instrumental advances have been made in PCNL to reduce morbidity and improve effectiveness. A thorough review of the recent literature identified five major areas of progress for the advancement of PCNL: patient positioning, method of percutaneous access, development of lithotriptors, miniaturized access tracts, and postoperative nephrostomy tube management. This review provides an overview of recent advancements in PCNL and the outcomes of each area of progress and notes how much we achieve with less invasive PCNL. This information may allow us to consider the future role and future developments of PCNL.

Efficacy of endoscopic combined intrarenal surgery in the prone split-leg position for staghorn calculi

Abstract Purpose: To evaluate the efficacy of endoscopic combined intrarenal surgery (ECIRS) using retrograde flexible ureteroscopy and miniature percutaneous nephrolithotomy (PNL) for the treatment of patients with staghorn calculi in the prone split-leg position.

PATIENTS AND METHODS

We retrospectively reviewed the records of 42 patients with staghorn calculi (45.8±3.2 mm) who underwent ECIRS using retrograde flexible ureteroscopy and miniature PNL in the prone split-leg position for the treatment of staghorn calculi in our center between December 2010 and August 2013. A flexible ureteroscope with a laser fiber was inserted through a ureteral access sheath, and lithoclast lithotripsy was performed through a mini-percutaneous tract. Both procedures were performed simultaneously by two urologists. Surgical parameters, including surgical time, stone-free (SF) rates, modified Clavien complication grades, and risk factors for residual stones, were analyzed.

RESULTS

Fifteen patients (35.7%) had complete staghorn calculi. Among the 42 staghorn calculi treated, 23 had 0 to 5 stone branches, 14 had 6 to 10 stone branches, and 5 had ≥11 stone branches. All procedures were performed successfully using a single lithotripsy tract with the patient in the prone split-leg position. The mean surgical time was 143.2±9.2 minutes. The initial SF rate was 71.4%, and the final SF rate was 83.3% after further treatment. One patient required a blood transfusion (2.4%), but no patient experienced a ≥3 Clavien grade complication. Risk factors for residual stones were stone size, stone surface area, complete staghorn calculi, and the number of stone branches.

CONCLUSIONS

ECIRS for staghorn calculi in the prone split-leg position is a safe, efficient, and versatile method for the effective management of staghorn calculi without the creation of multiple percutaneous tracts.

Does Peak Inspiratory Pressure Increase in the Prone Position? An Analysis Related to Body Mass Index

PURPOSE

Percutaneous nephrolithotomy is commonly performed with the patient prone. There is concern that the prone position, especially in obese patients, negatively affects ventilation due to the restriction of chest compliance and respiratory mechanics. We analyzed the change in airway resistance between supine and prone positioning of patients undergoing percutaneous nephrolithotomy.

MATERIALS AND METHODS

We retrospectively reviewed the intraoperative respiratory parameters of 101 patients who underwent prone percutaneous nephrolithotomy. Peak inspiratory pressure was assessed with the patient supine, at several time points after being turned prone and at the end of the case. The change in peak inspiratory pressure with time was calculated. Results were stratified based on body mass index and data were compared using the paired t-test and Spearman ρ.

RESULTS

Of 101 patients 50 (50%) were obese (body mass index 30 kg/m(2) or greater). Median body mass index was 25.6 kg/m(2) in the nonobese cohort and 38.3 kg/m(2) in the obese cohort. Average peak inspiratory pressure while supine and prone was 18.0 and 18.5 cm H2O in the nonobese cohort, and 25.5 and 26.6 cm H2O, respectively, in the obese cohort. Obese patients had significantly higher peak inspiratory pressure in the supine and the prone positions relative to nonobese patients (p <0.0001). However, there was no change in peak inspiratory pressure from the supine to the prone position in either cohort.

CONCLUSIONS

Obese patients have higher baseline peak inspiratory pressure regardless of position. However, prone positioning does not impact peak inspiratory pressure in either cohort. It remains a safe and viable option.

Mini percutaneous nephrolithotomy in the treatment of renal and upper ureteral stones: Lessons learned from a review of the literature

The aim of this review is to present the most recent data regarding the indications of mini percutaneous nephrolithotomy (PCNL), the results and the complications of the method. Medline was searched from 1997 to January 2014, restricted to English language. The Medline search used a strategy including medical subject headings and free-text protocols. PCNL is a well-established treatment option for patients with large and complex renal calculi. In order to decrease morbidity associated with larger instruments like blood loss, postoperative pain and potential renal damage, a modification of the technique of standard PCNL has been developed. This is performed with a miniature endoscope via a small percutaneous tract (11–20 F) and was named as minimally invasive or mini-PCNL. This method was initially described as an alternative percutaneous approach to large renal stones in a pediatric patient population. Furthermore, it has become a treatment option for adults as well, and it is used as a treatment for calculi of various sizes and locations. However, the terminology has not been standardized yet, and the procedure lacks a clear definition. Nevertheless, mini-PCNL can achieve comparable stone-free rates to the conventional method, even for large stones. It is a safe procedure, and no major complications are reported. Although less invasiveness has not been clearly demonstrated so far, mini-PCNL is usually related to less blood loss and shorter hospital stay than the standard method.

Supine pediatric percutaneous nephrolithotomy (PCNL)

INTRODUCTION/BACKGROUND

Many authors reported their experience with supine PCNL in adult population comparing the outcome with prone PCNL and they found that the stone free rate and the operative time were in favor of prone PCNL with a lower patient morbidity among patients with supine PCNL. This encouraged us to perform supine PCNL in pediatric population.

AN OBJECTIVE

In this study we evaluated the safety and efficacy of supine PCNL in pediatric population.

STUDY DESIGN (SUBJECTS/PATIENTS/MATERIALS/METHODS)

Between April 2011 and February 2014 a total of 27 children (6 girls and 21 boys) presented with renal calculi. The stones were single pelvic stone in 14 cases, pelvic stone with lower calyceal stones in 7 cases and pelvic stone with upper calyceal stones in 6 cases. The mean stone size was 32 mm (range 20-47 mm). All patients were managed with supine PCNL performed by a single surgeon. Marking the posterior axillary line in standing position before the operation is a mandatory initial step. The patients were placed in supine position with elevation of the ipsilateral shoulder and hip by means of two bags one underneath the shoulder and the other underneath the hip to widen the operative field. The technique was performed using a sheathless 19 fr. Richard wolf rigid nephroscope after acute tract dilation by amplatz dilators. Complications (intraoperative and postoperative) and stone free rate rates were reported.

RESULTS

A single lower calyceal access was used in all cases through which we could successfully remove even the upper calyceal stones. Kinking of the guide wire during tract dilatation were encountered in 4 cases and the guide wire was successfully exchanged using a small Teflon dilator in 2 cases while ultrasonographic guided lower calyceal repuncture was done in 2 cases. The average operative time (from the beginning of the puncture trial to nephrostomy tube insertion) was (41 ± 15) min. The operation was successfully completed as planned in all cases with two cases of intraoperative complications (one case of pelvicalyceal system perforation and another case of intraoperative bleeding and blood transfusion). The initial stone free rate was (92.5%). Postoperative complications was reported in the form of 2 cases of fever that respond to medical treatment for 72 h.

DISCUSSION

The main advantages of supine pediatric PCNL is that it is comfortable for the surgeon, the anesthetist and the child. The main disadvantages of supine pediatric PCNL is that it is not familiar for most urologists and small field of operation. The short outcome of our study is the small number of cases and the lack of comparative study with prone pediatric PCNL.

CONCLUSIONS

Pediatric supine PCNL is a safe and effective method for management of pediatric renal stones. It carries the advantages of easily upper calyx access through the lower calyceal tract, low incidence of fluid absorption or hypothermia and easy anesthesia monitoring. However a larger number of cases are needed to be evaluated.