Techniques for fluoroscopic percutaneous renal access

Reducing hand radiation during renal access for percutaneous nephrolithotomy: a comparison of radiation reduction techniques

Percutaneous nephrolithotomy confers the highest radiation to the urologist's hands compared to other urologic procedures. This study compares radiation exposure to the surgeon's hand and patient's body when utilizing three different techniques for needle insertion during renal access. Simulated percutaneous renal access was performed using a cadaveric patient and separate cadaveric forearm representing the surgeon's hand. Three different needle-holding techniques were compared: conventional glove (control), a radiation-attenuating glove, and a novel needle holder. Five 300-s fluoroscopy trials were performed per treatment arm. The primary outcome was radiation dose (mSv) to the surgeon's hand. The secondary outcome was radiation dose to the patient. One-way ANOVA and Tukey's B post-hoc tests were performed with p < 0.05 considered significant. Compared to the control (3.92 mSv), both the radiation-attenuating glove (2.48 mSv) and the needle holder (1.37 mSv) reduced hand radiation exposure (p < 0.001). The needle holder reduced hand radiation compared to the radiation-attenuating glove (p < 0.001). The radiation-attenuating glove resulted in greater radiation produced by the C-arm compared to the needle holder (83.49 vs 69.22 mGy; p = 0.019). Patient radiation exposure was significantly higher with the radiation-attenuating glove compared to the needle holder (8.43 vs 7.03 mSv; p = 0.027). Though radiation-attenuating gloves decreased hand radiation dose by 37%, this came at the price of a 3% increase in patient exposure. In contrast, the needle holder reduced exposure to both the surgeon's hand by 65% and the patient by 14%. Thus, a well-designed low-density needle holder could optimize radiation safety for both surgeon and patient.

Anatomical approach to PCNL: concept of ideal puncture zone in a 3D perspective

To describe a concept of ideal 'puncture zone' as against any single ideal 'puncture tract' for percutaneous nephro-lithotomy (PCNL) and present our results. Through this narrative, we aim to reduce the gaps in inter-understanding of an erstwhile description of ideal tract and real-life puncture making. The puncture zone principle was applied for our novel puncture making technique during PCNL. The largest imaginary cone that can fit into a respective calyx, with its tip in the pelvis defines the 'puncture zone' for that calyx. This concept allows fine-tuning of the ideal puncture tract based upon the desired corresponding manipulation zone and also shifts the focus of puncture making to infundibulum anatomy from the tip of calyx. The surgical technique and retrospective review of 136 cases done between 2015 and 2021 using this concept are presented. Primary outcome included stone-free rate, pseudo-aneurysm and blood transfusion at 3 months of follow-up. 33 cases had multiple (> 3) stones, 21 only calyceal/infundibular stones, eight partial staghorn and 12 were complete staghorn stones. Mean stone size was 29 ± 15 (Range: 5-53) mm. Complete clearance was achieved in 127 cases, four of which required two tracts. Blood transfusion was required in one case. No pseudo-aneurysms were encountered. The puncture zone concept has provided good results in our hands. It may help easier understanding of PCN puncture making and provides a background for reconciliation between description of an ideal tract and practical puncturing techniques used by different surgeons.

Ultrasound-Guided PCNL - Why Are We Still Performing Exclusively Fluoroscopic Access?

PURPOSE OF REVIEW

While urologists are traditionally taught to perform percutaneous nephrolithotomy (PCNL) utilizing exclusively fluoroscopy, ultrasound has emerged as a safe alternative. This article showcases the major reasons why ultrasound-guided access should be considered the first-line approach for performing access for PCNL.

RECENT FINDINGS

There continues to be a need to further reduce radiation exposure in the management of kidney stone patients. This review showcases how performing ultrasound-guided PCNL has been associated with a shorter learning curve, increased patient safety, and the ability to perform x-ray free PCNL. Ultrasound-guided PCNL is not only an achievable skill for urologists to learn but provides multiple advantages over traditional fluoroscopic access. As every effort should be given to help reduce radiation exposure for kidney stone patients as well as performing surgeons and operating theater personnel, endourologists should strive to add this technique to their armamentarium.

Superselective renal arterial embolization for severe postpercutaneous nephrolithotomy haemorrhage: clinical characteristics and risk factors for initial failure

OBJECTIVE

To identify the clinical characteristics of patients who underwent superselective renal arterial embolization (SRAE) after percutaneous nephrolithotomy (PCNL) and to explore the risk factors for failed initial SRAE after PCNL.

MATERIALS AND METHODS

Patients who underwent SRAE for severe haemorrhage following PCNL between January 2014 and December 2020 were included in the study. The clinical data of those patients and the parameters and characteristics of the perioperative PCNL and SRAE procedures were collected and analysed.

RESULTS

A total of 243 patients were included in this study. A total of 139 patients (57.2%) had a pseudoaneurysm, 25 (10.3%) had an arteriovenous fistula, 50 (20.6%) patients had both a pseudoaneurysm and an arteriovenous fistula, and 29 (11.9%) had an arterial laceration. In 177 patients with single percutaneous access, 125 (70.6%) patients exhibited nontract haemorrhage, and 55 (31.1%) patients exhibited multiple bleeding sites. In 66 patients with multiple percutaneous access, 44 (66.7%) patients exhibited nontract haemorrhage, and 32 (48.5%) patients exhibited multiple bleeding sites. The decrease in Hb before SRAE was 41.4 ± 19.8 g/L. The mean time between PCNL surgery and initial SRAE was 6.4 ± 4.9 days. Serum creatinine was increased after the SRAE procedure. Initial SRAE was successful in 229 (94.2%) patients and failed in 14 (5.8%) patients. Multivariate regression demonstrated that hydronephrosis < 20 mm, total ultrasonographic guidance, solitary kidney, previous ipsilateral renal surgery, PCNL duration > 90 min and multiple bleeding sites were potential risk factors for initial embolization failure.

CONCLUSION

Percutaneous access was not the most important reason for post-PCNL severe haemorrhage. SRAE is effective for the treatment of severe haemorrhage following PCNL; however, several factors have an impact on the success of initial SRAE. Additionally, the SRAE procedure may affect renal function.

Non-papillary prone percutaneous nephrolithotomy for renal abnormalities: single-institution experience

PURPOSE

To evaluate the effectiveness and safety of non-papillary prone PCNL for the treatment of patients with renal abnormalities.

METHODS

An observational retrospective cohort study including PCNL cases of patients with renal abnormalities was performed. The following inclusion criteria were applied: renal stones > 1.5 cm with maximal diameter, anatomical malformations of affected kidney (malrotated kidneys, horseshoe kidneys and kidneys with complete duplicated systems, medullary sponge kidney), patients treated with standard (30Fr) PCNL or mini-PCNL (22Fr). The lithotripsy was performed using the Lithoclast Master or the Lithoclast^® Trilogy (EMS Medical, Nyon, Switzerland).

RESULTS

Overall, 57 patients, 35 males, and 22 females with any renal malformation underwent non-papillary prone PCNL. Our study included 25 patients with horseshoe kidneys, 21 with malrotated kidneys, 9 with kidneys with duplicated pelvicalyceal systems and 2 with medullary sponge kidneys. The mean cumulative stone size was 36 ± 1.4 mm and most of the stones were in the lower calyceal group (36.9%) and in the pelvis (27.2%). The stone-free rate (SFR) was 84.2% and the mean hospitalization time was 2.7 ± 0.7 days. In total, postoperative complications were developed in six patients (10.5%), half of them presenting fever and the other half requiring blood transfusion (Grade II).

CONCLUSION

The PCNL is the method of choice for treating large stones in anomalous kidneys. The generally accepted panacea that only a papillary puncture is safe is questioned by our results. Based on our experience, a non-papillary puncture proved to be a safe and effective procedure.

On Surgical Planning of Percutaneous Nephrolithotomy with Patient-Specific CTRs

Percutaneous nephrolithotomy (PCNL) is considered a first-choice minimally invasive procedure for treating kidney stones larger than 2 cm. It yields higher stone-free rates than other minimally invasive techniques and is employed when extracorporeal shock wave lithotripsy or uteroscopy are, for instance, infeasible. Using this technique, surgeons create a tract through which a scope is inserted for gaining access to the stones. Traditional PCNL tools, however, present limited maneuverability, may require multiple punctures and often lead to excessive torquing of the instruments which can damage the kidney parenchyma and thus increase the risk of hemorrhage. We approach this problem by proposing a nested optimization-driven scheme for determining a single tract surgical plan along which a patient-specific concentric-tube robot (CTR) is deployed so as to enhance manipulability along the most dominant directions of the stone presentations. The approach is illustrated with seven sets of clinical data from patients who underwent PCNL. The simulated results may set the stage for achieving higher stone-free rates through single tract PCNL interventions while decreasing blood loss.

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

OBJECTIVES

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Application of Three-dimensional Visualization Fused with Ultrasound for Percutaneous Renal Puncture

We present here the three-dimensional (3D) visualization fused with ultrasound and to evaluate its clinical application effect preliminarily. One hundred and eighteen patients with renal calculi in our hospital from September 2017 to December 2019 were prospectively randomized into two groups. The experimental group was treated with percutaneous renal puncture guided by the 3D visualization fused with ultrasound. The control group was treated with percutaneous renal puncture guided by B-ultrasonography (B-US). The puncture time in the experimental versus control group was 4.36 ± 1.28 min versus 10.72 ± 2.94 min (P = 0.000), operation time was 65.85 ± 10.63 min versus 81.34 ± 12.52 min (P = 0.000), and the loss of hemoglobin was 8.55 ± 3.76 g/L min versus 13.33 ± 5.81 g/L(P = 0.000), and the success rate of establishing the channel at one time was 98.41% versus 81.82% (P = 0.002), and the coincidence rate between the channel and the longitudinal axis of the target renal calyx was 88.89% versus 60.00% (P = 0.000). The 3D visualization fused with ultrasound could guide precise puncture to target calyces, reduce operation time, bleeding, and difficulty of puncture.

Deep-learning-aided forward optical coherence tomography endoscope for percutaneous nephrostomy guidance

Percutaneous renal access is the critical initial step in many medical settings. In order to obtain the best surgical outcome with minimum patient morbidity, an improved method for access to the renal calyx is needed. In our study, we built a forward-view optical coherence tomography (OCT) endoscopic system for percutaneous nephrostomy (PCN) guidance. Porcine kidneys were imaged in our experiment to demonstrate the feasibility of the imaging system. Three tissue types of porcine kidneys (renal cortex, medulla, and calyx) can be clearly distinguished due to the morphological and tissue differences from the OCT endoscopic images. To further improve the guidance efficacy and reduce the learning burden of the clinical doctors, a deep-learning-based computer aided diagnosis platform was developed to automatically classify the OCT images by the renal tissue types. Convolutional neural networks (CNN) were developed with labeled OCT images based on the ResNet34, MobileNetv2 and ResNet50 architectures. Nested cross-validation and testing was used to benchmark the classification performance with uncertainty quantification over 10 kidneys, which demonstrated robust performance over substantial biological variability among kidneys. ResNet50-based CNN models achieved an average classification accuracy of 82.6%±3.0%. The classification precisions were 79%±4% for cortex, 85%±6% for medulla, and 91%±5% for calyx and the classification recalls were 68%±11% for cortex, 91%±4% for medulla, and 89%±3% for calyx. Interpretation of the CNN predictions showed the discriminative characteristics in the OCT images of the three renal tissue types. The results validated the technical feasibility of using this novel imaging platform to automatically recognize the images of renal tissue structures ahead of the PCN needle in PCN surgery.

A Multi-institutional Review of Single-access Percutaneous Nephrolithotomy for Complex Staghorn Stones

BACKGROUND

With the heterogeneous distribution of novel surgical technologies and variable physician training, there is a need to re-evaluate contemporary outcomes of percutaneous nephrolithotomy (PCNL) for complex staghorn stones.

OBJECTIVE

To evaluate contemporary outcomes of guideline-supported treatment for patients with staghorn kidney stones using single-access PCNL in multiple North American centers.

DESIGN, SETTING AND PARTICIPANTS

We performed a multi-institutional retrospective review of staghorn stones managed from January 1, 2017 to January 1, 2019, inclusive. We excluded patients with more than a single percutaneous access per renal unit and those who underwent a concomitant contralateral procedure.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Safety (Clavien-Dindo complications) and efficacy in terms of a strictly defined stone-free rate were examined for single-access PCNL performed on staghorn stones with a Guy's stone score of 3-4.

RESULTS AND LIMITATIONS

We evaluated 301 patients meeting the inclusion criteria with an average age of 57 yr (range 18-87). All stones had a Guy's stone score of 3 (36.2%) or 4 (63.8%). The mean (± standard deviation) stone burden was 191.4 ± 49.8 mm². Of the 297 patients (98.6%) who underwent computed tomography on postoperative day 1, 132 (44.4%) showed no residual stone, 111 (37.3%) had a largest fragment <4 mm, and 54 (18.2%) had a fragment ≥4 mm after primary single-access PCNL. Secondary procedures were performed in 117 patients (38.9%). Imaging at 3 mo demonstrated that 210/257 patients (82%) were stone-free. The overall complication rate was 17.9%, with 11 patients (3.7%) experiencing Clavien-Dindo grade ≥3 complications.

CONCLUSIONS

Single-access PCNL for complex staghorn stones is safe and effective. High stone-free rates with minimal morbidity are achievable with current techniques.

PATIENT SUMMARY

This study confirms that single-access percutaneous nephrolithotomy provides excellent outcomes in the treatment of complex kidney stones. This surgical technique has both safe and effective outcomes that are reproducible across multiple centers in North America.

Air vs contrast pyelogram for initial puncture access in percutaneous nephrolithotomy: a randomized controlled trial

Percutaneous nephrolithotomy (PCNL) is a standard procedure for large renal stones. Contrast (traditionally) as well as air is being used to delineate pelvi-calyceal system (PCS) to perform initial puncture. Contrast, when used has certain disadvantages including poor differentiation of anterior and posterior calyces. In this interim analysis of 122 patients of a prospective study subjects were stratified in two groups: in group 1, contrast was used while in group 2, air was used to delineate PCS. Out of 122,103 patients underwent puncture by contrast or air exclusively while 19 patients required mix of contrast and air (14 patients failed puncture using contrast while 5 using air). Mean dosage of radiation exposure (8.43 vs. 14.26 mGy), duration of radiation exposure (0.66 vs. 1.02 min), access time (3.72 vs. 5.84 min), were less in group 2 as compared to group 1. 84.5% of patients underwent puncture in single attempt in group 2 as compared to 56.25% in group 1. Five patients had post-operative fever and one had trans-pleural tract dilation. Complete stone clearance was seen in 94.8% of patients using air to only 75% of patients using contrast. Conclusion: Air pyelogram is a feasible, safe, cost effective and efficient access alternative to contrast pyelogram and in difficult situation a mixture of both is better than using one.

Patient Counseling Through the Pelvicalyceal-shaped Labyrinth: In Search of an Easy Understanding of the Upcoming Stone Removal: A Pilot Study

OBJECTIVE

To investigate the impact of a mobile application (app) displaying a visualization of the internal anatomy of the pelvicalyceal systemPCS and of kidney stones on patient understanding of their affected kidney anatomy and their upcoming percutaneous nephrolithotripsy (PCNL).

MATERIALS AND METHODS

One-hundred patients who required PCNL were included in this study, and all patients were nonrandomly distributed into 2 groups: counseled using only 3D-reconstructed computed tomography (CT) images (group 1) or using only the "InsKid" app (group 2). Patient data were obtained from CT scans as Digital Imaging and Communications in Medicine format and converted into stereolithography (STL) format. All patients completed the questionnaire after counseling, and the results were compared between groups.

RESULTS

Patients from group 2 better understood the anatomy of their affected kidney by 53%; awareness regarding their stone location was better by 32%; the steps of planned surgery, as well as possible complications, were more transparent for patients using the app by 24% and 56%, respectively. The number of patients who were dissatisfied with the mobile counseling dropped by 70%. The average duration of consultation with the 3D reconstruction of CT images was 10.9 ± 0.6 min, while counseling using our program reliably led to a reduction in this duration (7.3 ± 0.5 min).

CONCLUSION

The InsKid app is a freely available, easy-to-use educational software that improves patient counseling without considerable financial expense or long waiting periods for use.

Morphometry scores: Clinical implications in the management of staghorn calculi

Due to their large size, rapid growth, and attendant morbidity, staghorn calculi are complex clinical entities that impose significant treatment-related challenges. Moreover, their relative heterogeneity-in terms of both total stone burden and anatomic distribution-limits the ability to standardize their characterization and the reporting of surgical outcomes. Several morphometry systems currently exist to define the volumetric distribution of renal stones, in general, and to predict the outcomes of percutaneous nephrolithotomy; however, they fall short in their applicability to staghorn stones. In this review, we aim to discuss the clinical utility of morphometry systems and the influence of pelvicalyceal anatomy on the management of these complex calculi.

Critical causes in severe bleeding requiring angioembolization after percutaneous nephrolithotomy

Background

To identify the risk factors for severe bleeding requiring angioembolization among patients who received transfusions after PCNL, particularly those who underwent anatomically incorrect renal puncture.

Methods

A total of 53 patients, who received transfusions after PCNL and simultaneously had a postoperative CT scan performed between November 2009 and May 2019 at two teaching hospitals, were retrospectively reviewed. The patients were divided into two groups: those who underwent angioembolization and those who did not. Patient, stone and procedural factors were compared between the two groups. Puncture correctness was evaluated using postoperative CT scans. Puncture was defined as being a correct puncture if the fornix or papilla of the posterior calyx was punctured and the trajectory of the tract was within 20 degrees posterior to the frontal plane of the kidney (i.e., within Brödel’s line).

Results

21 patients underwent angioembolization after PCNL. Incorrect puncture was seen in 14/21 (66.7%) patients who underwent angioembolization after PCNL, whereas it was seen in 11/32 (34.4%) patients who did not undergo angioembolization (p = 0.021). On multivariable regression analysis, puncture correctness was found to be the only significant factor, with an OR of 3.818, 95% CI of 1.192–12.231 and p value of 0.024.

Conclusions

Incorrect renal puncture was related to severe bleeding requiring angioembolization after PCNL. Our results emphasize the importance of the basic principle of renal puncture for PCNL.

Efficacy and Safety of Supracostal Access for Mini Percutaneous Nephrolithotomy in Pediatric Patients

OBJECTIVE

To evaluate the efficacy and safety of supracostal percutaneous nephrolithotomy (PCNL) through the 11th intercostal space and compare it with subcostal PCNL in children with renal calculi.

MATERIALS AND METHODS

Children with renal calculi who underwent PCNL between January 2010 and December 2017 were divided into 2 groups: supracostal PCNL (group 1) and subcostal PCNL (group 2). Stone location, stone burden, location of the access points, operative time, postoperative visual pain score, success rate, hospital stay, and complications according to the modified Clavien classification were compared. Comparison of medians was done using Mann Whitney U test and the means were compared using t test.

RESULTS

Group 1 had 50 patients while group 2 had 60 patients. The stone-free rate was 84.0% and 85.0% in groups 1 and 2, respectively after 1 session of PCNL (P = .885). After auxiliary procedures, it increased to 96.0% and 96.6%, respectively (P = .852). The mean fall in hematocrit was 0.9% in group 1 and 1.5% in group 2 (P = .11) whereas the median pain score was 4 in group 1 and 3 in group 2 (P = .37). In all, 54 complications were recorded the commonest among which were grade I (81.5%). Twenty-nine complications were observed in group 1 while 25 complications were observed in group 2 (P = .088). One patient developed nephropleural fistula while another patient developed hydropneumothorax. Both belonged to group 1.

CONCLUSION

Supracostal access for PCNL is an effective and safe alternative to subcostal access for children with renal calculi in terms of stone-free rate and complications.

Supine percutaneous nephrolithotomy: tips and tricks

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

A hypothetical method for calculation of the access point, direction angle and access angle for percutaneous nephrolithotomy

Urinary stone disease has an increasing prevalence across the globe, and endoscopic treatment modalities have replaced open surgery. Percutaneous nephrolithotomy (PCNL) is a successful, safe and reliable minimally invasive method in the treatment of renal stones, especially big (≥2 cm) or complex ones. Gaining access is the most critical step of this procedure, which can affect the rest of the operation. Although previously described techniques, eye of the needle and triangulation techniques, are being used for gaining access, urologists (especially novice ones) can still have problems during this step. Some navigation concepts have been developed in order to make the access safer, easier and more successful, however, none of them has been incorporated in daily routine practice till now because of either complicated techniques or requirement of sophisticated equipment. Our hypothesis is that the access point, direction angle and access angle in order to touch a stone during PCNL can be calculated by the data obtained from the computed tomography images with the help of mathematical formulations, namely the theorem of the cosine.

Techniques for fluoroscopy-guided percutaneous renal access: An analytical review

Percutaneous renal access is a key step for a successful percutaneous nephrolithotomy. It involves the use of fluoroscopy, ultrasonography, or a combination of both. Over the years, various techniques have been proposed for fluoroscopy-guided access, and this article reviews the different techniques along with the anatomical principles for fluoroscopy-guided percutaneous renal access. A literature search was performed using "PubMed" for relevant literature describing the various techniques for fluoroscopy-guided percutaneous renal access. Each technique was analyzed in regard to how it describes selecting the skin site for puncture and determines the angle and depth of puncture. The advantages, limitations, and variations of these techniques were also studied. Each technique has its advantages and limitations. No study has compared all the techniques either in vivo or in vitro. Only a comparative study would establish the superiority of one technique over the other. Until this is done, endourologists should be well versed with the existing techniques.

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.

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.

Biplanar oblique access technique: A new approach to improve the success rate of percutaneous nephrolithotomy

Introduction:

Achieving suitable percutaneous access to the kidney is the most important step in percutaneous nephrolithotomy. The triangulation biplanar access technique under fluoroscopy is the standard method to achieve percutaneous renal access, but it is not successful in all cases. We used the new biplanar oblique access technique as a rescue method for the failed standard biplanar technique. The aim of this study was to evaluate the effects of this oblique access technique on access outcome.

Methods:

In total, 782 percutaneous nephrolithotomy procedures were performed under the standard triangulation biplanar technique. The biplanar access failed in 35 cases. Access failure was defined as no urine dropping from the needle or inability to insert the guide wire into the renal pelvis or selected calyx. In 28 failed access cases, the lower calyx was the targeted calyx. We used the oblique access technique for these cases. Initially, the arm of fluoroscopy was in the vertical position. Then the fluoroscopy device was rotated to 30° near the surgeon and 30° caudal to the patient and the needle was inserted into the appropriate calyx.

Results:

Percutaneous nephrolithotomy procedures were performed by the oblique access technique in 28 patients. Successful access was achieved in eight patients by the oblique technique (success access rate = 28.6%). No major or minor complication occurred in these patients.

Conclusion:

The oblique technique is an auxiliary method for accessing the lower calyx in cases which the standard triangular biplanar method has failed. As the failure rate of the biplanar technique is low, the oblique technique can be considered as a useful method for percutaneous access.

Comparison of two different renal access techniques in one-stage percutaneous nephrolithotomy: triangulation versus eye of the needle

BACKGROUND

Two primary methods used to create appropriate percutaneous renal access under fluoroscopic guidance are the triangulation technique (TT) and the "eye of the needle" (EN) technique. To the best of our knowledge, no study has yet compared the EN versus TT renal access methods that precede one-stage dilatation during percutaneous nephrolithotomy (PCNL).

OBJECTIVES

Compare effects of renal access techniques on the stone-free rate of one-stage PCNL, and the influence on outcomes.

DESIGN

Retrospective cross-sectional study.

SETTINGS

Tepecik Training and Research Hospital, Turkey.

PATIENTS AND METHODS

The records of patients with renal stones larger than 2 cm in diameter who underwent PCNL in our hospital between January 2008 and September 2017 were retrieved. Patients who had undergone one-stage PCNL with the EN renal access technique (EN group) were compared with patients who had undergone one-stage PCNL with the TT renal access technique (TT group).

MAIN OUTCOME MEASURES

Operative time, stone size, access location, stone side, length of hospital stay, Hounsfield unit (HU), fluoroscopy time, change in hemoglobin level, complications (modified Clavien classification) and stone-free rate.

SAMPLE SIZE

195.

RESULTS

Of 272 records, 195 met inclusion criteria. The one-stage PCNL stone-free rate and other outcomes did not differ significantly between the EN (n=91, 46.7%) and TT groups (n=104, 53.3%).

CONCLUSION

According to our study, renal access for one-stage PCNL can be achieved using either the EN or TT technique. The renal access technique used does not independently affect the complication rate.

LIMITATIONS

Retrospective, small sample size, and no comparison of body mass index.

CONFLICT OF INTEREST

None.

Characterising endourologist learning curve during percutaneous nephrolithotomy: implications on occupational dose and patients

In this study we have characterised the learning curve for percutaneous nephrolithotomy procedures over 301 cases for six years. Different surrogate parameters of clinical expertise have been used, such as dose area product, total procedure time, fluoroscopy time and personal equivalent doses. In addition, two different endourologists have been monitored; one of whom had specific Radiation Protection training (ICRP 85). Eye lens dose was estimated from thermoluminescent dosimeters. Significant differences were observed between both endourologists, especially in the fluoroscopy time. Finally, both entrance skin dose and effective doses of patients have been determined.

Validity of a sponge trainer as a simple training model for percutaneous renal access

Objective

To evaluate the efficacy of our simply designed trainer for junior urologists to acquire the initial skills for percutaneous renal access (PRA).

Subjects and methods

Three sponge sheets (60 × 50 × 10 cm) were arranged horizontally over each other. A rectangular groove was made in the middle sheet to accommodate an inflated balloon of a Foley catheter, radio-opaque metal balls, metal rings, or a plastic tube that were sequentially placed for the four training tasks. In each session, 18 trainees were asked to pass a fluoroscopically guided puncture needle from a surface point to the placed object in middle sheet. Clinical impact of training was evaluated by an experience survey on a 5-piont Likert scale (for model usefulness, tactile and fluoroscopic-guidance feedback) and success rate in further mentored practice.

Results

There was a gradual increase in tasks’ and sessions’ scores over the training sessions. According to the experience survey after first clinical practice, the mean (SD) score for overall model usefulness by trainees was 3.8 (0.9) with high fluoroscopic guidance reality [3.6 (1.1)] but poor tactile realism [2.3 (0.9)]. On mentored PRA, the success rate for trainees was 78.3%.

Conclusion

Our early evaluation showed our novel, cost-effective and reproducible sponge trainer could be an effective training model for PRA with a beneficial impact on subsequent clinical practice.

Percutaneous Nephrolithotomy Puncture and Tract Dilation: Evidence on the Safety of Approaches to the Infundibulum of the Middle Renal Calyx

OBJECTIVE

To investigate the anatomical relations of the papillary, infundibular, and pelvic approach to percutaneous nephrolithotomy and evaluate the amount of vascularization at the respective sites.

MATERIALS AND METHODS

^99mTc-dimercaptosuccinic acid single-photon emission computed tomography/computed tomography (SPECT/CT) renal scintigraphies or computed tomography perfusion (CTP) was performed in 40 patients (prone n = 20 or supine position n = 20). The angle of approach (AoA) for access tracts and the respective regions of interest to the mid-calyceal papilla and infundibulum as well as renal pelvis were designed and compared.

RESULTS

The design of access tracts aiming to the renal pelvis, papilla, and infundibulum of the renal calyx was impossible for the nondilated collecting systems as all these tracts were in close vicinity. In both SPECT/CT and CTP, there was no statistical difference between the AoA for infundibular or pelvic access in comparison with the papillary puncture in either prone or supine position regardless of the degree of dilation of the system. The comparison of the measurements in the regions of interest showed that there was no difference in blood supply between the infundibular and pelvic access in comparison with the papillary approach in both positions regardless of the degree of collecting system dilation.

CONCLUSION

The use of SPECT/CT and CTP showed that the punctures to the mid-calyceal renal papilla-fornix and infundibulum as well as the renal pelvis at the same level have similar AoA. The sites of the parenchyma involved in the tract dilation of the respective approaches are not related to significant differences in terms of vascularization.

European Section of Urotechnology educational video on fluoroscopic-guided puncture in percutaneous nephrolithotomy: all techniques step by step

OBJECTIVE

To describe the most common fluoroscopic-guided access techniques during percutaneous nephrolithotomy (PCNL) in a step-by-step manner and to assist in the standardisation of their technique and terminology.

METHODS

A high-quality animation video was created for each of the respective fluoroscopic techniques, focusing into the parallel projection of external surgical manoeuvres and their effect in the three-dimensional space of the kidney.

RESULTS

Four predominant fluoroscopic-guided percutaneous access techniques are available, each with different advantages and limitations. Monoplanar access is used when a stable single-axis fluoroscopic generator is available and is mostly based on surgeons' experience. Biplanar access uses a second fluoroscopy axis to assess puncture depth. The 'bull's eye' technique follows a coaxial to fluoroscopy puncture path and is associated with a shorter learning curve at the cost of increased hand radiation exposure. Hybrid and conventional triangulate techniques use target projection by two fluoroscopic planes to define the exact localisation of the target in space and access it through a third puncture site.

CONCLUSIONS

Fluoroscopic guidance during PCNL puncture is a very efficient method for access establishment. The percutaneous surgeon should be familiar with all available variations of fluoroscopic approach in order to be prepared to adapt puncture technique for any given scenario.

Surgical outcomes of percutaneous nephrolithotomy in 3402 patients and results of stone analysis in 1559 patients

OBJECTIVE

To report our experience of a series of percutaneous nephrolithotomy (PCNL) procedures in a single centre over 18 years in terms of patient and stone characteristics, indications, stone clearance and complications, along with the results of chemical analysis of stones in a subgroup.

PATIENTS AND METHODS

We retrospectively analysed the outcomes of PCNL in 3402 patients, who underwent the procedure between 1997 and 2014, obtained from a prospectively maintained database. Data analysis included patients' age and sex, laboratory investigations, imaging, punctured calyx, duration of operation, volume of irrigation fluid, radiation exposure time, blood transfusion, complications and stone-free status at 1-month follow-up. For the present analysis, outcomes in relation to complications and success were divided in two eras, 1997-2005 and 2006-2014, to study the differences.

RESULTS

Of the 3402 patients, 2501 (73.5%) were male and 901 (26.5%) were female, giving a male:female ratio of 2.8:1. Staghorn (partial or complete) calculi were found in 27.5% of patients, while 72.5% had non-staghorn calculi. Intracorporeal energy sources used for stone fragmentation included ultrasonography in 917 patients (26.9%), pneumatic lithoclast in 1820 (53.5%), holmium laser in 141 (4.1%) and Lithoclast^® master in 524 (15.4%). In the majority of patients (97.4%) a 18-22-F nephrostomy tube was placed after the procedure, while 69 patients (2.03%) underwent tubeless PCNL. The volume of the irrigation fluid used ranged from 7 to 37 L, with a mean of 28.4 L. The stone-free rate after PCNL in the first era studied was 78%, vs 83.2% in the second era, as assessed by combination of ultrasonography and plain abdominal film of the kidney, ureter and bladder. The complication rate in the first era was 21.3% as compared with 10.3% in the second era, and this difference was statistically significant. Stone analysis showed pure stones in 41% and mixed stones in 58% of patients. The majority of stones consisted of calcium oxalate.

CONCLUSIONS

This is the largest series of PCNL reported from any single centre in Pakistan, where there is a high prevalence of stone disease associated with infective and obstructive complications, including renal failure. PCNL as a treatment method offers an economic and effective option in the management of renal stone disease with acceptable stone clearance rates in a resource-constrained healthcare system.

The Circle Nephrostomy Tube: An Attractive Nephrostomy Drainage System Following Complex Percutaneous Nephrolithotomy

OBJECTIVE

To describe our experience with the circle nephrostomy tube (NT) (Cook Medical), a drainage system uniquely designed for use after multiple-access percutaneous nephrolithotomy (PNL).

METHODS

A retrospective review of 1317 consecutive patients undergoing 1599 PNLs at IU Health Methodist Hospital was performed. All multiple access cases utilizing circle NTs were reviewed and analyzed. The method of insertion of circle NT was demonstrated.

RESULTS

A total of 1843 accesses were obtained in 1599 renal units (RUs): 380 upper pole, 129 interpolar, and 1334 lower pole. Multiple accesses in this series were required in 282 RUs (17.6%). Following multiple-access PNL, circle NTs, Cope loop, and reentry Malecot NTs were inserted in 91 RUs (32.3%), 208 RUs (73.8%), and 31 RUs (11%), respectively. None of the patients who had circle NT experienced clogging, dislodgement, or obstruction of the tube. The cost of circle, Cope loop, and Malecot NTs are 121.73 USD, 95.20 USD, and 81 USD, respectively.

CONCLUSION

Circle NTs are easy to insert, secure, cost-effective compared with inserting two NTs. Circle NTs provide excellent drainage and facilitate secondary procedures.

Mini access guide to simplify calyceal access during percutaneous nephrolithotomy: A novel device

Introduction:

A precise puncture of the renal collecting system is the most essential step for percutaneous nephrolithotomy (PCNL). There are many techniques describing this crucial first step in PCNL including the bull's eye technique, triangulation technique, free-hand technique, and gradual descensus technique. We describe a novel puncture guide to assist accurate percutaneous needle placement during bull's eye technique.

Methods:

The mini access guide (MAG) stabilizes the initial puncture needle by mounting it on an adjustable multidirectional carrier fixed to the patient's skin, which aids in achieving the “bull's eye” puncture. It also avoids a direct fluoroscopic exposure of the urologist's hand during the puncture. Sixty consecutive patients with solitary renal calculus were randomized to traditional hand versus MAG puncture during bull's eye technique of puncture and the fluoroscopy time was assessed.

Results:

The median fluoroscopy screening time for traditional free-hand bull's eye and MAG-guided bull's eye puncture (fluoroscopic screening time for puncture) was 55 versus 21 s (P = 0.001) and the median time to puncture was 80 versus 55 s (P = 0.052), respectively. Novice residents also learned puncture technique faster with MAG on simulator.

Conclusion:

The MAG is a simple, portable, cheap, and novel assistant to achieve successful PCNL puncture. It would be of great help for novices to establish access during their learning phase of PCNL. It would also be an asset toward significantly decreasing the radiation dose during PCNL access.

Ultrasound Guidance Reduces Percutaneous Nephrolithotomy Cost Compared to Fluoroscopy

OBJECTIVE

To examine the cost factors associated with ultrasound and fluoroscopic guidance for percutaneous nephrolithotomy (PCNL) and to determine which method can be performed at a lower cost per case.

METHODS

A cost comparison study was performed utilizing clinical data from a prospectively maintained research database. We included the most recent 33 consecutive ultrasound-guided PCNL cases in 2016 and the most recent 40 consecutive fluoroscopy-guided PCNL cases before the operative surgeon transitioned to ultrasound guidance in May 2014. The total operative time and clinical outcomes were examined. Costs were extracted from the institution accounting systems and given a uniform multiplier to protect institutional financial reporting confidentiality. Comparisons were made using the Student t test and the chi-squared test.

RESULTS

After excluding outliers, 71 PCNL procedures were included in the analysis. Demographic data and stone characteristics were not different between ultrasound-guided and fluoroscopy-guided groups. However, the mean operative time for ultrasound-guided PCNL was significantly shorter (99.8 ± 27.0 vs 144.9 ± 55.1 minutes, P < .05). When capital equipment costs were included, the mean total cost per case of ultrasound-guided PCNL was approximately 30% less than fluoroscopy-guided PCNL (simulated costs with a uniform multiplier; $5258.90 ± 957.12 vs $7508.60 ± 1163.83, P < .05). Postoperative clinical outcomes were comparable between the 2 groups.

CONCLUSION

When capital costs are included, ultrasound-guided PCNL can produce comparable clinical outcomes to fluoroscopy-guided procedures at a lower cost to the institution. Shorter operative time drives significant savings with the adoption of ultrasound guidance, which may be magnified with increasing case volume. Using ultrasound imaging during PCNL may be more cost-effective compared to fluoroscopy and warrants further study.

Feasibility of Retrograde Ureteral Contrast Injection to Guide Ultrasonographic Percutaneous Renal Access in the Nondilated Collecting System

OBJECTIVES

Ultrasound-guided percutaneous nephrolithotomy (PCNL) has become increasingly utilized. Patients with nondilated collecting systems represent a challenge: the target calix is often difficult to visualize. Here we report pilot study results for retrograde ultrasound contrast injection to aid in percutaneous renal access during ultrasound-guided PCNL.

PATIENTS AND METHODS

From April to July 2016, consecutive patients over the age of 18 years with nondilated collecting systems on preoperative imaging who presented for PCNL were enrolled. B-mode ultrasound imaging was compared with contrast-enhanced mode with simultaneous retrograde injection of Optison™ via an ipsilateral ureteral catheter.

RESULTS

Five patients (four males and one female) with renal stones underwent PCNL with retrograde ultrasound contrast injection during the study period. Mean body mass index was 28.3 ± 5.6 kg/m² and mean stone size was 24.5 ± 12.0 mm. Under B-mode ultrasound, all patients demonstrated nondilated renal collecting systems that appeared as hyperechoic areas, where it was difficult to identify a target calix for puncture. Retrograde contrast injection facilitated delineation of all renal calices initially difficult to visualize under B-mode ultrasound. Renal puncture was then performed effectively in all cases with a mean puncture time of 55.4 ± 44.8 seconds. All PCNL procedures were completed without intraoperative complications and no adverse events related to ultrasound contrast injection occurred.

CONCLUSION

Retrograde ultrasound contrast injection as an aide for renal puncture during PCNL is a feasible technique. By improving visualization of the collecting system, it facilitates needle placement in challenging patients without hydronephrosis. Future larger scale studies comparing its use to standard ultrasound-guided technique will be required to validate this concept.

A prospective and randomised trial comparing fluoroscopic, total ultrasonographic, and combined guidance for renal access in mini-percutaneous nephrolithotomy

OBJECTIVE

To compare the safety and efficacy of fluoroscopic guidance (FG), total ultrasonographic guidance (USG), and combined ultrasonographic and fluoroscopic guidance (CG) for percutaneous renal access in mini-percutaneous nephrolithotomy (mini-PCNL).

PATIENTS AND METHODS

The present study was conducted between July 2014 and May 2015 as a prospective randomised trial at the First Affiliated Hospital of Guangzhou Medical University. In all, 450 consecutive patients with renal stones of >2 cm were randomised to undergo FG, USG, or CG mini-PCNL (150 patients for each group). The primary endpoints were the stone-free rate (SFR) and blood loss (haemoglobin decrease during the operation and transfusion rate). Secondary endpoints included access failure rate, operating time, and complications. S.T.O.N.E. score was used to document the complexity of the renal stones. The study was registered at http://clinicaltrials.gov/ (NCT02266381).

RESULTS

The three groups had similar baseline characteristics. With S.T.O.N.E. scores of 5-6 or 9-13, the SFRs were comparable between the three groups. For S.T.O.N.E. scores of 7-8, FG and CG achieved significantly better SFRs than USG (one-session SFR 85.1% vs 88.5% vs 66.7%, P = 0.006; overall SFR at 3 months postoperatively 89.4% vs 90.2% vs 69.8%, P = 0.002). Multiple-tracts mini-PCNL was used more frequently in the FG and CG groups than in the USG group (20.7% vs 17.1% vs 9.5%, P = 0.028). The mean total radiation exposure time was significantly greater for FG than for CG (47.5 vs 17.9 s, P < 0.001). The USG had zero radiation exposure. There was no significant difference in the haemoglobin decrease, transfusion rate, access failure rate, operating time, nephrostomy drainage time, and hospital stay among the groups. The overall operative complication rates using the Clavien-Dindo grading system were similar between the groups.

CONCLUSIONS

Mini-PCNL under USG is as safe and effective as FG or CG in the treatment of simple kidney stones (S.T.O.N.E. scores 5-6) but with no radiation exposure. FG or CG is more effective for patients with S.T.O.N.E. scores of 7-8, where multiple percutaneous tracts may be necessary.

Ultrasound-Guided Renal Access for Percutaneous Nephrolithotomy: A Description of Three Novel Ultrasound-Guided Needle Techniques

Ultrasound-guided renal access for percutaneous nephrolithotomy (PCNL) is a safe, effective, and low-cost procedure commonly performed worldwide, but a technique underutilized by urologists in the United States. The purpose of this article is to familiarize the practicing urologist with methods for ultrasound guidance for percutaneous renal access. We discuss two alternative techniques for gaining renal access for PCNL under ultrasound guidance. We also describe a novel technique of using the puncture needle to reposition residual stone fragments to avoid additional tract dilation. With appropriate training, ultrasound-guided renal access for PCNL can lead to reduced radiation exposure, accurate renal access, and excellent stone-free success rates and clinical outcomes.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

Comparison of safety and efficacy of laparoscopic pyelolithotomy versus percutaneous nephrolithotomy in patients with large renal pelvic stones: a meta-analysis

To compare percutaneous nephrolithotomy (PCNL) and laparoscopic pyelolithotomy (LP) for surgical management for large (>2 cm) renal stones. We searched MEDLINE, Cochrane, and EMBASE databases until March 11, 2015, using the following search terms: renalpelvic stone, percutaneous nephrolithotomy, laparoscopic pyelolithotomy. Randomized controlled and prospective and retrospective two-armed studies were included. Sensitivity analysis and assessment of the quality of the included studies and publication bias were performed. Nine studies were included in the study with a patient population of 622. The studies were homogeneous with respect to the primary end point of stone-free rate, but were heterogeneous with respect to operation time, length of hospital stay, and blood loss. A higher percentage of patients who received LP remained stone-free following surgery compared with patients who were treated with PCNL (p=0.001). However, the mean operation time was longer for patients with LP than for those treated with PCNL (p=0.002). There was no difference between procedures with regard to length of hospital stay or blood loss (p≥0.071). Sensitivity and quality analysis indicated that the data are reliable and the included studies are of good quality. No publication bias was observed. The study suggests that both procedures are effective and safe for removing large renal stones. However, LP may be more efficacious than PCNL in treating large kidney stones.

What is better in percutaneous nephrolithotomy - Prone or supine? A systematic review

OBJECTIVE

To review the literature reporting the technique of percutaneous nephrolithotomy (PCNL) and outcomes for prone and supine PCNL, as PCNL is an established treatment for renal calculi and both prone and supine PCNL have been described, but there has been much debate as to the optimal position for renal access in PCNL.

METHODS

A review of the medical literature was conducted using the PubMed database to identify relevant studies reporting on prone and supine PCNL published up until July 2015. Only publications in English were considered. Search terms included 'supine', 'prone', 'percutaneous nephrolithotomy', 'PCNL' and 'randomised controlled trial'. Articles relevant to the particular aspect of PCNL discussed were selected.

RESULTS

In all, 30 articles were included in the literature review. Nine of these articles were of Level 1 Evidence as graded by the Oxford System of Evidence-based Medicine.

CONCLUSION

The present systematic review highlights the benefits and disadvantages of supine and prone PCNL. The published data on supine and prone PCNL have shown no significant superiority of either approach. Whether prone or supine PCNL is optimal, remains a debatable topic.

Direct Endoscopic Visualization Combined with Ultrasound Guided Access during Percutaneous Nephrolithotomy: A Feasibility Study and Comparison to a Conventional Cohort

PURPOSE

Percutaneous nephrolithotomy access may be technically challenging and result in significant radiation exposure. In an attempt to reduce percutaneous nephrolithotomy radiation exposure, a novel technique combining ultrasound and direct ureteroscopic visualization was developed and reviewed.

MATERIALS AND METHODS

Ureteroscopy without fluoroscopy was used to determine the optimal calyx for access, which was punctured with a Chiba needle under percutaneous ultrasound guidance. Next a wire was passed into the collecting system and ureteroscopically pulled into the ureter using a basket. Tract dilation and sheath and nephrostomy tube placement were performed under direct ureteroscopic visualization. Twenty consecutive patients undergoing this novel technique were reviewed and compared to 20 matched patients treated with conventional percutaneous nephrolithotomy. Mann-Whitney U and Pearson chi-square tests were used for comparisons with p <0.05 considered significant.

RESULTS

Using this novel technique mean fluoroscopy access time was 3.5 seconds (range 0 to 27.9) and mean total fluoroscopic time was 8.8 seconds (range 0 to 47.1). Mean operative time was 232 minutes (range 87 to 533), estimated blood loss was 111 ml, the stone-free rate was 65% and the complication rate was 25%. Compared to 20 matched conventional percutaneous nephrolithotomy cases, there was no difference in operative time (p=0.76), estimated blood loss (p=0.64), stone-free rate (p=0.50) or complications (p=1.00). However, the novel technique resulted in a significant reduction in fluoroscopy access time (3.5 vs 915.5 seconds, p <0.001) and total fluoroscopy time (8.8 vs 1,028.7 seconds, p <0.001).

CONCLUSIONS

This study demonstrates the feasibility of combined ultrasound and ureteroscopic assisted access for percutaneous nephrolithotomy. A greater than 99% reduction in fluoroscopy time was achieved using this technique.