Renal access by urologist or radiologist during percutaneous nephrolithotomy

Comparison of radiation exposure for interventional radiology vs urology-guided renal access for percutaneous nephrolithotomy

INTRODUCTION

Radiation exposure during percutaneous nephrolithotomy (PCNL) can vary depending on the method used for renal access. This study aimed to compare fluoroscopy time and dose during PCNL when renal access is achieved via interventional radiology (IR) versus urology.

METHODS

A retrospective review of patients who underwent unilateral PCNL between January 2020 and February 2023 was conducted. Patients were categorized by renal access method: endoscopic combined intrarenal surgery performed by a urologist (ECIRS) or IR-assisted. A Wilcoxon rank-sum test and multivariate analyses were done to compare several parameters of the two groups.

RESULTS

66 patients underwent ECIRS (group 1), and 31 underwent IR-assisted access (group 2). The groups were similar in age, BMI, sex, and stone size. The difference in medians for fluoroscopy dose, fluoroscopy time, operative time and length of stay were statistically significant (p < 0.001). Average fluoroscopy dose (39.6 vs. 327 mGy) and time (1.46 vs. 10.9 min), along with average operative time (1.97 vs. 3.00 h) and length of stay (1.26 vs 3.06 days) were all lower in group 1. In the IR group, a positive correlation was noted between BMI and fluoroscopy dose (p < 0.001), though this correlation was absent with ECIRS.

CONCLUSIONS

PCNL with ECIRS access significantly reduces radiation exposure and operative time compared to IR-assisted access. Additionally, BMI influenced radiation exposure and operative time in the IR group, but not in the ECIRS group. Endoscopic renal access may lower overall radiation exposure and postoperative complications.

Robotic Surgery for Stone Disease

PURPOSE OF REVIEW

To evaluate recent literature regarding the role of robotic technology in the treatment of nephrolithiasis with particular attention to complex technical procedures.

RECENT FINDINGS

Robotic platforms including single-port robotics have been widely adopted in urological practice for the treatment of both malignant and benign conditions and has led to an expansion of the utilization of robot-assisted surgery to tackle challenging clinical scenarios such as bladder neck reconstruction, upper urinary tract reconstruction, and more recently complex stone disease. Presently, the American Urological Association guidelines on the surgical management of stones advise against using robotic, open, or laparoscopic techniques as a first-line approach for most patients with stone disease with the exception for patients with anatomical abnormalities, large or complex stones, or patients requiring a concomitant reconstructive operation. Clinicians have demonstrated the safety and feasibility of surgical robotics in the treatment of stone disease for a variety of operations including robotic pyeloplasty, pyelolithotomy, ureterolithotomy, and surgical interventions in urinary diversions as well as novel technologies for robotic ureteroscopy and percutaneous access. Numerous clinicians have demonstrated the safety and feasibility of using robot-assisted surgery to treat nephrolithiasis, mainly in complex renal anatomy. Further research is necessary to identify the best candidates for utilization of robotics in complex stone disease, and further technological developments will continue to further advance the use of these platforms in the treatment of nephrolithiasis.

Percutaneous Nephrolithotomy Access: A Meta-Analysis Comparing Access by Urologist vs Radiologist

Introduction: Percutaneous nephrolithotomy is a minimally invasive procedure indicated for the management of staghorn calculi or renal calculi >2.0 cm. Percutaneous renal access is a critical step in this procedure and can be performed by either urologists or interventional radiologists. The purpose of this study is to perform a meta-analysis to compare outcomes between urologist and interventional radiologist-mediated access. Methods: An electronic literature search was conducted to identify studies comparing urologist- and interventional radiologist-acquired access. Studies must have included both urologist- and intervention radiologist-acquired access data but were excluded if (1) not in English; (2) abstract without full text; (3) unable to determine who acquired access; and (4) only included either urologist or interventional radiologist data. Meta-analysis comparison was generated with the Review Manager 5.4 software. Results: After screening the abstracts and title, 55 relevant studies were identified. Nine articles were utilized in the meta-analysis. Urologist-acquired access was associated with a greater stone-free rate (risk ratio [RR] = 1.10; 95% confidence interval [CI], 1.01-1.20), a reduction in major complications (RR = 0.69; 95% CI, 0.53-0.92), and a shorter hospital stay (mean difference -0.40; 95% CI, -0.64 to -0.16) in comparison with radiologist-acquired access. Urologist-acquired access was associated with greater blood loss (mean difference 0.46; 95% CI, 0.32-0.60) when compared with interventional radiology-acquired access. No significant differences were found with regard to unusable access, multiple tracts, supracostal access, ancillary procedure requirement, operative time, minor complications, and transfusions. Conclusions: Urologist-acquired access may be associated with a higher stone-free rate and a reduction in major complications, whereas interventional radiologist-mediated access may be associated with a reduction in blood loss, despite similar transfusion rates.

Pattern of key opinion leaders talks at major international urological meetings reflects the main differences in flexible ureteroscopy and PCNL diffusion

OBJECTIVE

To analyze the pattern of speaker activity related to both flexible ureteroscopy (fURS) and percutaneous nephrolithotomy (PCNL) during plenary sessions at the main (endo)urological international meetings over the last 10 years.

METHODS

We reviewed the meeting programs of the main endourological international meetings (EAU, AUA, WCE, and SIU) during 2011-2019. We detected all invited speakers at plenary sessions regarding fURS or PCNL. The proportion of fURS and PCNL talks was evaluated yearly during the study period. In order to analyze plenary session speaker composition, we estimated and compared the mean number of talks per speaker according to surgical technique. We also analyzed possible differences in age distribution according to the topic of the talk as well as the presence of young (i.e., < 45 years) speakers. Data were analyzed using descriptive statistics.

RESULTS

During the last 10 years, a total of 498 plenary talks were found. Of those, 260 (52.2%), 211 (42.4%), and 27 (5.4%) discussed PCNL, fURS, or both, respectively. PCNL was more frequently discussed at the beginning and the end of the study period. Mean [SD] number of talks per speaker was higher for PCNL (2.9 [3.4] vs 1.6 [1.4], p < 0.001), meaning that a wider variety of speakers was invited to give fURS talks. Speakers discussing fURS were younger (median [interquartile range, IQR] age 48 [44-56] vs 52 [47-60] years, p < 0.001), and a higher proportion of young speakers was observed in the fURS group (26% vs 15% p < 0.001). PCNL speakers were more commonly discussing fURS than fURS speakers discussing PCNL (23% vs 17%, p = 0.43).

CONCLUSIONS

We found a wider variety of speakers at fURS plenary sessions as compared to PCNL ones. It is easier and quicker to become an internationally recognized expert in the field of fURS rather than PCNL. PCNL speakers were able to master fURS more frequently than the other way around.

Electromagnetic-guided puncture: a tool or a tale?

PURPOSE OF REVIEW

The puncture technique and site of the puncture can impact the clinical outcome and the development of postoperative adverse events following percutaneous nephrolithotomy (PCNL). The aim of the current review was to discuss the available puncture guidance approaches and outline the potential role of the recently introduced electromagnetic-guided method.

RECENT FINDINGS

The puncture and PCNL tract establishment is usually performed using fluoroscopic or ultrasound guidance or a combination of two approaches. Electromagnetic-guided puncture is one of the most recent advancements of technology. The puncture navigation to the renal collecting system is available after placing a special wire with an electromagnetic tracking sensor into the desired calyx through the flexible ureterorenoscope. The available experimental and clinical studies have shown a high first puncture rate, decreased median time for obtaining a puncture, and shorter learning curves for beginners.

SUMMARY

Fluoroscopic and ultrasound guidance are the main approaches used by urologists. However, these modalities require a steep learning curve, approximately 60 cases for reaching competency. The initial data on electromagnetic navigation have shown the feasibility and potential promising outcomes of this novel approach. New studies are required to investigate its potential implementation opportunities in the daily practice of urologists.

Automated Needle Targeting with X-ray (ANT-X) - Robot-assisted device for percutaneous nephrolithotomy (PCNL) with its first successful use in human

INTRODUCTION

To make percutaneous access easier in PCNL, we developed Automated Needle Targeting with X-ray (ANT-X).

METHOD

ANT-X uses an image registration software with a closed loop feedback system to autoalign the puncture needle to the desired calyx using the bullseye technique. We tried percutaneous punctures on a live pig model and compared the results with free-hand technique. We then performed our first PCNL in a human subject with the aid of ANT-X. Our patient was a 48 year-old gentleman with a 1.4cm left lower pole stone.

RESULTS

Initial results for live animal trial showed radiation exposure for robot-assisted arm during puncture was reduced by 26% compared to the free-hand technique (8.2mGy vs 11.2mGy). In the human trial, obtaining percutaneous access was successful at first attempt.

CONCLUSION

ANT-X system can help surgeons feel confident and potentially reduce complications, hence enabling more surgeons to adopt this procedure.

Surgical Trends in Nephrolithiasis: Increasing De Novo Renal Access by Urologists for Percutaneous Nephrolithotomy

Purpose: Percutaneous nephrolithotomy (PCNL) has wide variability in the methods of renal access. In many centers, this is done as a separate nephrostomy procedure by interventional radiology, while other urologists gain initial access themselves during the PCNL. We aimed to characterize these trends to confirm the need for continued training in this aspect of PCNL. Methods: Using MarketScan insurance claims, we examined surgical volume for ureteroscopy (URS), extracorporeal shockwave lithotripsy (SWL), and PCNL during 2007-2017. For PCNL, current procedural terminology (CPT) codes were used to identify the provider performing the de novo renal access over time. We stratified postoperative outcomes for PCNL by provider type. Results: From 2007 to 2017, the annual proportion of PCNL procedures peaked at 4.5%, with a recent decline in 2016 and 2017 to 3.2%. URS steadily increased from 46.3% to 60.0% of procedures, and SWL mirrored that change with a decrease from 50.0% to 36.7%. Within 19,743 PCNLs, there was a notable increase from 12.8% to 32.3% in the number of procedures with urologists performing de novo renal access. Most cases (40.0%) still had a de novo access code assigned to a radiologist. Length-of-stay, readmission, transfusion, and secondary stone procedure rates were higher in the radiologist-gained access PCNLs. Conclusions: URS has surpassed SWL as the most common stone procedure. While the proportion of PCNLs has remained fairly stable over the last decade, urologists obtaining their own de novo access have increased substantially. Continued outreach efforts focused on urologist-obtained access may further increase this proportion and improve outcomes for PCNL.

Simulation-Based Percutaneous Renal Access Training: Evaluating a Novel 3D Immersive Virtual Reality Platform

Introduction: Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for patients with a large stone burden. There are a variety of methods to teach this important endourologic procedure, including simulation. We evaluated three different PCNL simulation platforms for potential use in teaching and assessing percutaneous renal access skills. Materials and Methods: Urology residents, fellows, and faculty were recruited to participate in this study, which included completing standardized tasks on three PCNL simulation platforms: a virtual reality (VR) simulator (PercMentor, 3D Systems™), a porcine tissue simulator (Cook™ Medical), and a new 3D immersive VR simulator-Marion K181 (Marion Surgical™). Participants were asked to complete a standardized task-gaining prone percutaneous renal access using a fluoroscopic-guided technique. Participants were asked to rate the simulators, and performance data were recorded for analysis. Results: A total of 18 participants with varying levels of PCNL experience completed the study. The Marion K181 had higher ratings by participants in all domains (realism, tactile feedback, instrument movement, renal anatomy, fidelity of simulation, utility as teaching tool) compared with the PercMentor (p < 0.05) but did not differ in any domain when compared with the porcine PCNL model. Participants felt that the Marion K181 was comparable with the porcine PCNL model as a teaching tool, but had the advantage of not requiring radiation exposure. Fluoroscopy time was the variable that most consistently correlated with participant PCNL experience and level of training, across all three PCNL simulation platforms. Conclusions: There are a variety of PCNL simulation platforms available for teaching percutaneous renal access skills. Based on our initial comparative study, there is validity evidence to support the use of the novel Marion K181 PCNL simulator as a training tool rather than higher fidelity models requiring real radiation exposure. However, evidence is yet lacking for its use as an assessment tool.

A New Technique for Percutaneous Nephrolithotomy Using Retrograde Ureteroscopy and Laser Fiber to Achieve Percutaneous Nephrostomy Access: The Initial Case Report

Background: Percutaneous nephrolithotomy (PCNL) serves as the gold standard minimally invasive procedure to remove large renal stones. The puncture is made from the skin to the chosen calix under fluoroscopic guidance, although this remains a challenging technique. We describe the initial case of retrograde holmium laser acquired nephrostomy access.

Case Presentation: In this study, we present the case of a 48-year-old woman with right renal colic with imaging revealing a 2.6 cm staghorn stone. With institutional approval, we performed a new technique utilizing retrograde access with a flexible ureteroscope and a holmium laser fiber to achieve nephrostomy access for PCNL in the prone position. With the ureteroscope confirmed in the desired calix, the ureteroscope and laser fiber were aimed and fired toward the flank and thus creating a subcostal nephrostomy tract. PCNL was then carried out per standard of care lithotripsy techniques utilizing the holmium laser.

Conclusion: In this initial case, percutaneous retrograde laser access allowed for desired caliceal nephrostomy access under direct vision.

Laser Endoscopic X-Ray-Guided Intrarenal Tract: Comparison Among Renal Access Modalities in the Porcine Kidney

Introduction and Objectives: Laser endoscopic X-ray-guided intrarenal tract (LEXIT) is a recently described holmium laser retrograde access technique for creating percutaneous access during a percutaneous nephrolithotomy. We compared bleeding, ease of access, and the time to achieve access for each of the following three modalities: LEXIT, retrograde Lawson puncture wire, and antegrade 18-gauge nephrostomy needle access in the porcine kidney. Methods: Eight pigs underwent an average of five nephrostomy accesses per kidney under simultaneous laparoscopic vision at 5 mm Hg insufflation pressure. Data collected included: access time (seconds), bleeding intensity (scale: 1 [no bleeding] - 10 [severe bleeding]), bleeding duration (seconds), accuracy of caliceal entry, and surgeon comfort with the technique (scale: 1 [very easy] - 10 [very difficult]). Results: A total of 64 nephrostomy accesses were obtained. The speed of nephrostomy access with LEXIT was significantly faster than the nephrostomy needle and Lawson wire (p < 0.001). Bleeding intensity (p = 0.002) and severity (p = 0.001) were lower with the Lawson puncture wire, followed by LEXIT and then by the nephrostomy needle. LEXIT was rated as easier in acquiring access within the upper pole (p = 0.003) and interpolar calices (p < 0.001). Histopathology demonstrated no difference in parenchymal damage between LEXIT and nephrostomy needle (p = 0.18); however, LEXIT was associated with significantly increased peri-tract thermal injury, although within a narrow focus of 1.6 mm (p < 0.01). Conclusion: Among the three renal access techniques, LEXIT provided the fastest access times and greatest ease of access specifically for upper pole and interpolar calices. Also, bleeding with LEXIT was significantly less compared with the standard antegrade nephrostomy needle access. Histopathological analysis demonstrated that the holmium laser resulted in focal thermal tissue effects similar in range to the blunt tissue trauma caused by the 18-gauge nephrostomy needle.

Assessing Cost-Effectiveness of New Technologies in Stone Management

Diagnosis, treatment, and follow-up are all influential in determining the overall cost to the health care system for kidney stones. New innovations in the field of nephrolithiasis have been abundant, including disposable ureteroscopes, ultrasound-guided approaches to percutaneous nephrolithotomy, and advanced laser lithotripters. Identifying cost-effective treatment strategies encourages practitioners to be thoughtful about providing value-based high-quality care and remains on important principle in the treatment of urinary stone disease.

Is emergency percutaneous antegrade drainage of the upper urinary tract useful for future percutaneous nephrolithotomy access?

Purpose

To compare percutaneous nephrolithotomy (PCNL) operations between patients with a preoperative nephrostomy tube and patients that the renal access was obtained at the time of the surgery.

Materials and Methods

We retrospectively evaluated PCNL cases. Patients were divided into two groups. Group 1 – a non-nephrostomy tube (percutaneous nephrostomy, PCN) group and Group 2 – patients with a PCN placed before the procedure. All preoperatively placed PCN's were performed in emergency situations by interventional radiologists (IR). Complications were classified according to the Clavien-Dindo classification. We compared stone characteristics, operation time, complications, efficacy and PCN usability at surgery.

Results

Five hundred twenty-seven patients who were submitted to PCNL for renal stones were included in the study. In 73 patients (13.9%) the PCNs were placed before the surgery. Patients and stone characteristics, mean operative time (p=0.830), complications (p=0.859) and stone-free rates (93.0%) were similar between the groups. There was a trend toward higher complication rates in Group 1, but the difference was not statistically significant. Only 21 (29.0%) of preoperatively placed PCNs were used during PCNL for establishing a tract. The reasons for not using PCN tract were: pelvic or infundibular insertion (30.0%) and suboptimal anatomic location (70.0%).

Conclusions

Preoperative emergency inserted PCNs by IR usage rates were low during PCNL. Its placement neither affects the incidence of complications nor affects the operation time and outcomes. As such, when emergency renal drainage is indicated, the need for a future definitive PCNL should not influence the decision about the modality of renal drainage.

Salvage Percutaneous Nephrolithotomy: Analysis of Outcomes following Initial Treatment Failure

PURPOSE

Percutaneous nephrolithotomy has high potential for morbidity or failure. There are limited data regarding risk factors for failure and to our knowledge no published reports of surgical outcomes in patients with prior failed attempts at percutaneous stone removal.

MATERIALS AND METHODS

We identified patients referred to 3 medical centers after prior failed attempts at percutaneous nephrolithotomy. A retrospective chart review was performed to analyze reasons for initial failure and outcomes of salvage percutaneous nephrolithotomy. Outcomes were compared to those in a prospectively maintained database of more than 1,200 patients treated with a primary procedure.

RESULTS

Salvage percutaneous nephrolithotomy was performed in 31 patients. Unsuitable access to the stone was the reason for failure in 80% of cases. Other reasons included infection, bleeding and inadequate instrument availability in 6.5% of cases each. Compared to patients who underwent primary percutaneous nephrolithotomy those treated with salvage were more likely to have staghorn calculi (61.3% vs 31.4%, p <0.01) and a larger maximum stone diameter (3.7 vs 2.5 cm, p <0.01), and require a secondary procedure (65.5% vs 42.1%, p <0.01). There was no significant difference between the cohorts in the remaining demographics or perioperative outcomes. All patients were deemed completely stone free except one who elected observation for a 3 mm nonobstructing fragment.

CONCLUSIONS

Despite the more challenging nature and prior unsuccessful attempts at treatment, the outcomes of salvage percutaneous nephrolithotomy were no different from those of primary percutaneous nephrolithotomy when performed by experienced surgeons.

Percutaneous stone removal: new approaches to access and imaging

Percutaneous renal access and removal of large renal calculi was first described nearly 40 years ago and has since become the gold standard in management of large and complex renal calculi. In this same time period, technological and medical advances have allowed this procedure to develop in improved efficacy and morbidity. The following review offers an update to new approaches to percutaneous renal access and imaging in the management of large and complex renal calculi.

Fluoroscopy guided percutaneous renal access in prone position

Percutaneous nephrolithotomy is a very commonly done procedure for management of renal calculus disease. Establishing a good access is the first and probably the most crucial step of this procedure. A proper access is the gateway to success. However, this crucial step has the steepest learning curve for, in a fluoroscopy guided access, it involves visualizing a three dimensional anatomy on a two dimensional fluoroscopy screen. This review describes the anatomical basis of the renal access. It provides a literature review of all aspects of percutaneous renal access along with the advances that have taken place in this field over the years. The article describes a technique to determine the site of skin puncture, the angle and depth of puncture using a simple mathematical principle. It also reviews the common problems faced during the process of puncture and dilatation and describes the ways to overcome them. The aim of this article is to provide the reader a step by step guide for percutaneous renal access.

Contemporary assessment of renal stone complexity using cross-sectional imaging

Recently, several scoring systems have been proposed to predict outcomes of percutaneous nephrolithotomy, objectively and quantitatively assessing kidney calculi complexity using cross-sectional imaging. These scoring systems are promising new tools that can guide surgical decision making, predict surgical outcomes, counsel patients undergoing stone surgery, and improve standardized academic reporting in percutaneous kidney stone surgery. In this article, we review features of each of these systems, their similarities and differences, and their applicability in clinical practice and relevance in academic reporting.

Comparison of urologist- and radiologist-gained percutaneous renal access during PCNL: a review

Percutaneous renal access for percutaneous nephrolithotomy (PCNL) can be performed by either an interventional radiologist or urologist, depending on local expertise. We reviewed the current literature comparing the success and complications in gaining percutaneous access for both groups. An extensive literature search was carried out using Medline which included keywords “PCNL”, “PCNL access”, “percutaneous nephrolithotomy” and “percutaneous nephrostomy”. The search yielded six published articles that compared the success and complication rates between urologist- and radiologist-performed percutaneous access for PCNL. A systematic literature review was performed. Because of the considerable heterogeneity between studies, no pooling of data or statistical analysis was undertaken. In terms of success or complication rates, there was no significant difference between urologist- and radiologist-made percutaneous tracts. We observed, however, that there appears to be an argument that urologists are in a better position to make their own tracts, which requires only a single-stage procedure in theatre. There appears to be low uptake amongst urologists with the common beliefs that it is a radiological procedure, that radiologists have superior equipment, that it increases intraoperative time and that a steep learning curve is required for proficiency, suggesting that competence in percutaneous access would require at least 60 PCNL procedures. It is therefore unsurprising that many trainees may struggle to gain sufficient exposure to this technique, unless they are training in a centre with adequate patient numbers. Nonetheless, the papers reviewed illustrate that the urologists who are practicing this procedure are performing to an acceptably high standard. In conclusion there appears to be no difference in complication rates between the urologist- and the radiologist-made percutaneous tract. The steep learning curve required can be addressed by new teaching methods such as inanimate simulators, virtual-reality (VR) simulators, PCNL workshops and old-fashioned apprenticeships. A prospective study comparing urologist- and radiologist-placed nephrostomies would be beneficial.

Antegrade percutaneous flexible endoscopic approach for the management of urinary diversion-associated complications

PURPOSE

We present our experience in the minimally invasive management of postoperative complications associated with urinary diversions using an ureteral access sheath (UAS) in an antegrade approach.

PATIENTS AND METHODS

From 2005 to 2011, 21 antegrade flexible ureteroscopies (F-URS) were performed in 17 patients with a urinary diversion. Urinary diversions in this population consisted of ileal conduits, orthotopic neobladders, catheterizable pouches, and an ureterosigmoidostomy in 9, 5, 2, and 1 patients, respectively. The most important reason for treatment was recurrent upper urinary tract infection. The indication for intervention was stone disease in 15 procedures and strictures in 6 cases. In two patients, "staged-therapy" was performed. Using UAS in an antegrade approach was the main concept.

RESULTS

A nephrostomy tube was already in place in 14 (66.6%) procedures, which was the access route used. Successful puncture was performed in all other patients. Eighty percent of patients were rendered stone free after the first antegrade session. Moreover, all strictures were successfully managed by dilation. In two sequential procedures in a patient, there was an inability to perform stone treatment because of abnormal position of the ureter (kinked), which did not allow the ureterorenoscope to pass. All other procedures were uneventful. Postoperative complications were reported in four procedures. There was significant urinary tract infection in two patients as well as an obstructed nephrostomy tube in two patients.

CONCLUSION

An antegrade endoscopic procedure using UAS in patients who present with stones or ureterointestinal stricture as late complications of urinary diversion is a feasible, well-tolerated technique, especially when using smaller access sheaths.

Renal calyceal anatomy characterization with 3-dimensional in vivo computerized tomography imaging

PURPOSE

Calyceal selection for percutaneous renal access is critical for safe, effective performance of percutaneous nephrolithotomy. Available anatomical evidence is contradictory and incomplete. We present detailed renal calyceal anatomy obtained from in vivo 3-dimentional computerized tomography renderings.

MATERIALS AND METHODS

A total of 60 computerized tomography urograms were randomly selected. The renal collecting system was isolated and 3-dimensional renderings were constructed. The primary plane of each calyceal group of 100 kidneys was determined. A coronal maximum intensity projection was used for simulated percutaneous access. The most inferior calyx was designated calyx 1. Moving superiorly, the subsequent calyces were designated calyx 2 and, when present, calyx 3. The surface rendering was rotated to assess the primary plane of the calyceal group and the orientation of the select calyx.

RESULTS

The primary plane of the upper pole calyceal group was mediolateral in 95% of kidneys and the primary plane of the lower pole calyceal group was anteroposterior in 95%. Calyx 2 was chosen in 90 of 97 simulations and it was appropriate in 92%. Calyx 3 was chosen in 7 simulations but it was appropriate in only 57%. Calyx 1 was not selected in any simulation and it was anteriorly oriented in 75% of kidneys.

CONCLUSIONS

Appropriate lower pole calyceal access can be reliably accomplished with an understanding of the anatomical relationship between individual calyceal orientation and the primary plane of the calyceal group. Calyx 2 is most often appropriate for accessing the anteroposterior primary plane of the lower pole. Calyx 1 is most commonly oriented anterior.

Advances in percutaneous nephrolithotomy

Percutaneous nephrolithotomy (PCNL) is the most morbid of the minimally invasive surgeical procedures for stone removal. Over the last 2 decades, refinements in technique and new technology have improved the efficacy and the efficiency of the procedure. Although PCNL has long been the procedure of choice for large and complex stones, it is increasingly being used for moderate stone burdens because of its high stone-free rates and because of the limitations of shock wave lithotripsy and ureteroscopy. The article reviews advances in the technique and technology applied to percutaneous access, tract dilation, stone visualization, stone fragmentation, stone clearance, and postoperative management.

Flexible ureteroscopy-directed retrograde nephrostomy for percutaneous nephrolithotomy: description of a technique

We describe flexible ureteroscopy-directed retrograde nephrostomy access using a puncture wire to achieve renal access. This is a natural extension of modern retrograde intrarenal surgical techniques and a modernization of the original Lawson technique for retrograde nephrostomy tract creation. In appropriately selected patients, this approach is safe and permits reduced radiation exposure. We believe this technique is easy to learn and may overcome the difficult learning curve of antegrade nephrostomy techniques faced by urologists who have not undergone subspecialty training in endourology.

Ultrasonography-guided percutaneous nephrolithotomy for the treatment of urolithiasis in patients with scoliosis

We examined the surgical outcomes of minimally invasive percutaneous nephrolithotomy (MPCNL) in scoliotic patients with complicating urolithiasis. Two patients with scoliosis were hospitalized for MPNCL due to upper tract urolithiasis. Calyx puncture was performed in the prone position under ultrasonographic guidance. The renal access route was established using a set of 8F to 16F dilators, and a transpyelic ballistic lithotriptor was used to fragment the calculi. The stone burdens in the 2 patients were 410 mm(2) and 500 mm(2). The entire operative time was 40 to 70 minutes, and the mean time of establishing percutaneous access was 20 minutes. The calculi were completely removed by single-session pneumatic lithotripsy. The 2 patients recovered from MPCNL uneventfully, and the follow-up radiologic examinations identified no stone residual or recurrence. MPCNL is a minimally invasive modality that is effective and safe for the treatment of urolithiasis in patients with scoliosis.

Impact of percutaneous renal access technique on outcomes of percutaneous nephrolithotomy

BACKGROUND AND PURPOSE

Percutaneous nephrolithotomy (PCNL) is regarded as the gold standard for the treatment of patients with renal stones larger than 2 cm in diameter. Creating a percutaneous renal access is the initial and probably the most important step in performing a PCNL. Two primary methods of obtaining proper percutaneous renal access under fluoroscopic guidance are described: The "triangulation" and the "eye of the needle" techniques. In this article, we compare these two techniques in terms of success and complication rates.

PATIENTS AND METHODS

From October 2010 to May 2011, 80 patients with simple renal stones were prospectively randomized into two groups according to the percutaneous renal access technique used for PCNL. Patients in group 1 (n=40) were assigned to the eye of the needle technique, and patients in group 2 (n=40) were assigned to the triangulation method. Patients needing multiple access points were excluded from the study. The preoperative, operative, and postoperative follow-up findings were thereafter analyzed and compared.

RESULTS

No significant difference between the two groups was detected in terms of patient demographics (mean patient age, body mass index, stone size, or stone location). The operation time, fluoroscopic screening time (FST), and duration of hospitalization were similar in both groups (P=0.52, P=0.32, P=0.26, respectively). Patients in group 1 had a larger drop in hematocrit postoperatively than patients in group 2 (7.6 ± 3.7 vs 4.8 ± 2.1, P=0.001). The blood transfusion rate (7.5%) was similar in both groups, however. Although the complication rate was higher in group 1 than group 2, no significant difference was detected (20% vs 15%, P=0.76).

CONCLUSIONS

The present study demonstrates that PCNL can be performed safely using two different percutaneous access techniques. The two techniques studied in this trial had similar FSTs, operation and hospitalization times, success rates, and complication rates.

Percutaneous nephrolithotomy in the United kingdom: results of a prospective data registry

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is commonly used in the management of large upper renal tract stones. It is highly effective but carries a greater risk of significant morbidity than less invasive treatment options such as ureteroscopy or extracorporeal shock wave lithotripsy.

OBJECTIVE

Evaluate the current practice and outcomes of PCNL using a national prospective data registry.

DESIGN, SETTING, AND PARTICIPANTS

All surgeons undertaking PCNL in the United Kingdom were invited to submit data to an online registry.

MEASUREMENTS

Effectiveness was assessed by stone-free rates and safety according to complications including blood transfusion, fever, and sepsis rates.

RESULTS AND LIMITATIONS

Since January 2010, data on 987 patients who had 1028 PCNL procedures were collected. A total of 299 of 1012 procedures (30%) were for staghorn calculi, 299 (30%) for stones >2 cm, 329 (33%) for stones 1-2 cm, and 89 (9%) for stones <1cm. There were no significant differences in rates of failed access or complications according to whether a urologist or radiologist obtained renal access. There was a nonsignificant trend to a higher transfusion rate with balloon dilatation (7 of 222 [3.2%]) compared with serial dilatation (2 of 245 [0.8%]) of the renal tract (p = 0.093). Totally tubeless procedures were not associated with higher complication rates but did lead to a significant reduction in median length of stay (3 d vs 1.5 d; p<0.0001). Intraoperatively, 78% of patients were believed to be stone free, which was confirmed in 68% with postoperative imaging. Blood transfusion was required in 24 of 968 patients (2.5%). The incidence of postoperative fever was 16% and of sepsis was 2.4%.

CONCLUSIONS

The PCNL data registry is a unique resource providing vital information on current practice and critical outcome data. Using the registry, endourologists can audit their practice against national outcome data for this benchmark procedure. It will help surgeons counsel patients during consent for this complex endourologic procedure about the possible outcome in their hands.

Incidence, prevention, and management of complications following percutaneous nephrolitholapaxy

CONTEXT

Incidence, prevention, and management of complications of percutaneous nephrolitholapaxy (PNL) still lack consensus.

OBJECTIVE

To review the epidemiology of complications and their prevention and management.

EVIDENCE ACQUISITION

A literature review was performed using the PubMed database between 2001 and May 1, 2011, restricted to human species, adults, and the English language. The Medline search used a strategy including medical subject headings (MeSH) and free-text protocols with the keywords percutaneous, nephrolithotomy, PCNL, PNL, urolithiasis, complications, and Clavien, and the MeSH terms nephrostomy, percutaneous/adverse effects, and intraoperative complications or postoperative complications.

EVIDENCE SYNTHESIS

Assessing the epidemiology of complications is difficult because definitions of complications and their management still lack consensus. For a reproducible quality assessment, data should be obtained in a standardized manner, allowing for comparison. An approach is the validated Dindo-modified Clavien system, which was originally reported by seven studies. No deviation from the normal postoperative course (Clavien 0) was observed in 76.7% of PNL procedures. Including deviations from the normal postoperative course without the need for pharmacologic treatment or interventions (Clavien 1) would add up to 88.1%. Clavien 2 complications including blood transfusion and parenteral nutrition occurred in 7%; Clavien 3 complications requiring intervention in 4.1.%; Clavien 4, life-threatening complications, in 0.6%; and Clavien 5, mortality, in 0.04%. High-quality data on complication management of rare but potentially debilitating complications are scarce and consist mainly of case reports.

CONCLUSIONS

Complications after PNL can be kept to a minimum in experienced hands with the development of new techniques and improved technology. A modified procedure-specific Clavien classification should be established that would need to be validated in prospective trials.