Abstract
Purpose:
This study was developed to compare the clinical benefits associated with the use of balloon dilatators to those of metallic telescopic dilatators when used for the establishment of tracts in patients undergoing ultrasound-guided percutaneous nephrolithotomy.
Materials and methods:
This was a single-center retrospective study enrolling patients with urolithiasis who underwent ultrasound-guided percutaneous nephrolithotomy at Yuhuangding Hospital between 2011 and 2021. Patients were grouped based on the method used to establish percutaneous renal tracts, including balloon and metallic telescopic groups. The primary outcomes were overshooting rate, failure of access rate, and the efficiency of stone removal, while secondary outcomes included safety and economic benefits.
Results:
In total, 2269 patients were enrolled in this study, of whom 1222 (54%) and 1047 (46%) were in the balloon and metallic telescopic groups, respectively. Comparisons between the two groups did not reveal any superiority of the balloon group relative to the metallic telescopic group in overshooting rate (adjusted rate ratio (RR), 0.97; 95% confidence interval (CI), 0.73–1.27), failure of access rate (adjusted RR, 0.78; 95% CI, 0.52–1.16) and stone removal efficiency (adjusted RR, 1.03; 95% CI, 0.94–1.13). However, a significantly lower postoperative hemoglobin reduction value was observed in the balloon group relative to the metallic telescopic group (adjusted beta coefficient ratio: 7.19, 95% CI, 5.68–8.70). Balloon dilatator use was associated with better transfusion, embolization, surgical time, and hospital stay outcomes, whereas it was inferior in terms of costs.
Conclusion:
In patients undergoing ultrasound-guided percutaneous nephrolithotomy, balloon dilatator use for the establishment of percutaneous tracts is not superior to metallic telescopic dilatator use in terms of overshooting and failure of access and stone removal rates, but is superior in terms of the control of bleeding.
Plain language summary
This study compared two methods used to create pathways for kidney stone removal surgery, called percutaneous nephrolithotomy (PCNL). The two methods are balloon dilatators and metallic telescopic dilatators. The goal was to see which method works better in terms of success, safety, and cost. The study looked at 2,269 patients who had PCNL between 2011 and 2021. About half used balloon dilatators, and the other half used metallic telescopic dilatators. The researchers checked how often the methods caused problems like overshooting (going too far into the kidney) or failing to create the pathway. They also looked at how well the stones were removed, how much bleeding occurred, and the overall cost of the procedure. The results showed no significant difference between the two methods in terms of overshooting, failure to create the pathway, or how well the stones were removed. However, the balloon method caused less bleeding and led to shorter hospital stays compared to the metallic method. On the other hand, the balloon method was more expensive. In conclusion, both methods work similarly for creating pathways during PCNL, but the balloon method is safer in terms of bleeding and allows patients to leave the hospital sooner. However, it costs more. If cost is not a concern, the balloon method might be the better choice.
Introduction
Percutaneous nephrolithotomy (PCNL) is a minimally traumatic procedure associated with high stone clearance rates, such that it is the first-line approach to treating high-burden upper urinary tract stones. 1 PCNL requires the entry of the collecting system via the percutaneous renal tract for stone clearance, with tract dilation playing an essential role in percutaneous renal tract establishment. The continuous optimization of PCNL tract expansion technologies is important as a means of improving pathway establishment success rates and reducing postoperative complication incidence.2–4
In clinical settings, two of the most widely used tools for PCNL tract dilation are balloon dilatators and metallic telescopic dilatators.1,5,6 Both of these approaches, however, have the potential to cause surgical complications, including failed tract expansion, renal bleeding, damage to renal function, and the incidence of infection. 7 Establishing safe, effective, and affordable tract expansion strategies is thus essential. Prior studies have yielded inconsistent conclusions regarding the optimal approach to tract expansion.5,8–11 These contradictory findings may be attributable to the heterogeneous nature of patient populations and a failure to control for such heterogeneity when assessing surgical outcomes, thereby impacting result reliability. 5 As these studies generally include only limited numbers of cases, this also contributes to limitations in terms of the power of statistical analyses and an inability to fully capture all facets of operative outcomes. To overcome these issues, this study was developed as a single-center, retrospective study comparing the efficacy and safety of using balloon dilatators and metal telescopic dilatators for the establishment of PCNL tracts.
Materials and methods
Study oversight and design
This was a large-scale, single-center, retrospective study comparing the safety and efficacy of establishing PCNL tracts with a balloon dilatator or a metallic telescopic dilatator. All patients signed an informed consent form before the operation. The first author and the two final authors are responsible for ensuring the accuracy and completeness of all data and the fidelity of the study to the established research protocol.
Patients
Patients eligible for inclusion were individuals who had undergone PCNL for urolithiasis at Yantai Yuhuangding Hospital from 2011 to 2021. PCNL indications eligible for this study included kidney stones or upper ureteral stones over 2 cm in size, kidney stones or upper ureteral stones that had failed extracorporeal shock wave lithotripsy and flexible endoscopic treatment, symptomatic renal pelvis or diverticulum stones, specific types of stones, including horseshoe kidneys, transplanted kidneys with stones, ureteral stones with kidney stones, and obstruction of the renal pelvis ureteral junction. PCNL contraindications include untreated acute urinary system infections, patients who are unable to temporarily forgo anticoagulant or antithrombotic therapy, patients with uncorrected coagulation disorders, and patients who are under 18 years old or have a solitary kidney. If, after anti-infective treatment, the patient’s procalcitonin level remains above 0.5 ng/mL, body temperature is still above 37°C, surgery should be postponed, and antibiotic treatment should be continued. For patients with positive urine nitrite before surgery, we use antibiotic drugs such as levofloxacin for empirical treatment, and adjust the use of antibiotics based on urine culture results and drug sensitivity tests. Surgery will be performed after the urine culture results turn negative. If the prothrombin time is prolonged by more than 3 s, or activated partial thromboplastin time is prolonged by more than 10 s, or thrombin time is prolonged by more than 3 s, and the plasma fibrinogen level is below 1.5 g/l, with plasma D-dimer level above 1.0 μg/mL or fibrin degradation products above 10 μg/mL, we should identify the cause of the coagulation dysfunction, adjust the treatment plan according to the etiology, and proceed with surgery only after the results return to normal.
Patients were excluded if they lacked perioperative imaging data or underwent ureteroscopy combined with PCNL to treat unilateral kidney stones.
Patient grouping and treatment
The patients who underwent PCNL and were included in this study were separated into balloon and metallic telescopic dilation groups according to which of these approaches was used to establish the percutaneous renal tract.
In both groups, the surgical method included the positioning of the patient in a prone position, after which B-ultrasound guidance was used to puncture from the posterior axillary line of the 11th or 12th rib on the affected side to the renal pelvis. The puncture needle was then used to introduce a guide wire into the collection system, followed by an 8-Fr fascia expander being pre-expanded through the guide wire. For patients in the balloon dilation group, the tip of a balloon dilation catheter was then advanced along the guidewire into the target renal calyx. The above guidewire insertion process was performed under ultrasound guidance. The balloon was inflated with physiological saline at 20 atm, and its location and successful inflation were confirmed using real-time ultrasound monitoring. The outer sheath was passed over the inflated balloon, and the balloon was then removed. The sheath was kept in place as the working channel. An F20.8 nephroscope was then used to crush stones via ultrasonic lithotripter within the visible range. During the surgery, the stone clearance was determined by combining ultrasound with flexible nephroscopy, and postoperatively, a kidney CT was used to assess the stone clearance. For patients in the metal telescopic group, a dilatator was introduced along the guide wire to facilitate the gradual expansion of the channel, followed by the insertion of the outer sheath of the F24 nephroscope, followed by an F20.8 nephroscope. The ultrasound guidance system was distinct from the ultrasonic lithotripter used for stone fragmentation. Like the balloon dilation group, the ultrasonic lithotripter is used to fragment stones under real-time ultrasound localization provided by a B-ultrasound machine, utilizing the mechanical vibrations and cavitation effects generated by high-frequency ultrasound waves. Both of these surgical approaches entailed a postoperative nephrostomy tube and a JJ stent placement. During PCNL using both balloon dilatators and metallic telescopic dilatators, all steps were confirmed under ultrasound guidance, and no fluoroscopy was used to examine for residual stone fragments at the end of the surgery.
Data collection and outcomes
This study entailed a retrospective review of patient case records. Baseline data were the basic clinical data collected from these patients prior to or during PCNL procedures. A patient’s history of stones was based on their prior history of undergoing treatment for urolithiasis, including drug-based, surgical, or extracorporeal lithotripsy. Stones were classified into five categories according to their location and distribution on preoperative imaging, including staghorn, partial staghorn, calyceal, pelvic, and upper ureter stones. Whether or not patients underwent bilateral PCNL was used to classify them into unilateral and bilateral surgery groups.
Overshooting and failure of access are important detailed indicators for assessing the success of tract dilation, and they constitute the primary outcomes of this analysis. During the tract dilation process, if the dilator is overshooting into a nontarget renal pelvis, it may lead to excessive bleeding or even perforation, and also affect the stone clearance during the surgery. If the standard for tract establishment and nephroscope placement is not met due to excessive renal movement or previous surgeries on the patient, it is considered a failure of tract dilation. Stone clearance rate was the primary outcome for these analyses. On days 3–4 post-PCNL, stone clearance was assessed using renal CT, with residual stones <4 mm indicating complete clearance. The stone clearance rate was quantified as the percentage of all patients exhibiting stone clearance.
Safety outcomes included preoperative differences in indices, including hemoglobin levels, white blood cell (WBC) counts, neutrophil percentages, urinary WBCs, urine nitrite levels, serum creatinine, and estimated glomerular filtration rate. These values were assessed based on the final preoperative values and values collected on day 1 postoperatively for all patients. The statistics on urinary nitrite refer to the patients with positive urinary nitrite results after surgery. Whether or not patients required blood transfusion, renal artery embolism, and nephrectomy was also recorded.
Economic benefits were primarily assessed based on the length of hospitalization and the hospitalization’s overall costs, which included all costs from admission through discharge, including equipment, surgical supplies, and bed fees. The procedure costs of this study did not include preoperative bed fees and examination and testing costs for patients. Only surgical fees and postoperative expenses were calculated. The stone patients were uniformly arranged in standard wards, and potential variables were controlled for in this study.
Statistical analysis
These analyses were conducted in accordance with published statistical reporting guidelines for urological research and the Newcastle-Ottawa Scale Guidelines. 12
Categorical variables are presented as numbers and percentages, while continuous variables are presented as medians with interquartile ranges (IQRs). Multivariate logistic or linear regression approaches were used to compare primary, safety, and economic outcomes between patients in the balloon and metallic telescopic dilation groups, adjusting for parameters including age, sex, body mass index, diabetes history, urolithiasis history, renal colic, history of fever, maximum stone diameter, stone burden and site, surgical lateral, number of tracts, operative duration, year of surgery, and surgeon. For categorical variables, adjusted rate ratios (RRs) and 95% confidence intervals (CIs) were reported, whereas continuous outcomes were reported using adjusted beta coefficients with 95% CIs. Subgroup analyses based on baseline characteristics were conducted for the primary outcome and for any significant safety or economic outcomes. A two-sided p < 0.05 was considered significant, and all statistical analyses were performed with R (v 4.3.3).
Results
Patients
Between September 2011 and August 2021, 2460 patients were enrolled in this study, of whom 191 were excluded because they failed to meet with study’s inclusion criteria (Figure 1). The remaining 2269 patients were included in this study, of whom 1222 (54%) and 1047 (46%) underwent treatment with balloon dilatators and metal telescopic dilatators to establish channels, respectively. Patient baseline characteristics are detailed in Table 1. Of the enrolled patients, 426 (18.8%) exhibited staghorn stones, 638 (28.1%) exhibited partial staghorn stones, 466 (20.5%) exhibited calyceal stones, 580 (25.6%) exhibited renal pelvis stones, and 159 (7.0%) exhibited upper ureteral stones. The median maximum stone diameter was 28 mm (IQR, 25–32).
Cohort selection flowchart.
Demographic and clinical characteristics of the patients at baseline.
Values were calculated for continuous variables with the Wilcoxon test and for categorical variables with the chi-square test.
IQR, interquartile range.
Primary outcome
The success of the dilation process is the focus of comparison between the two groups. The two main issues related to the dilation process are overshooting and failure of access. Among the 2269 patients enrolled in this study, the overshooting rates were 9.5% and 13% in the balloon dilation group and the metallic telescopic group, respectively, with no significant difference between the two groups (RR, 0.97; 95% CI, 0.73–1.27, Table 2); the failure of access rates were 4.6% and 5.6% in the balloon dilation group and the metallic telescopic dilation group, respectively, with no significant difference between the two groups (RR, 0.78; 95% CI, 0.52–1.16, Table 2). The respective stone-free rates for the balloon and metallic telescopic groups were 92.6% and 90.7%, and there was no significant difference between these groups (RR, 1.03; 95% CI, 0.94–1.13, Table 2). Subgroup analyses were also conducted and achieved similar results (Supplemental Figures 1–3).
Multivariable-adjusted results for the relationships between outcome and dilatators.
Clinical characteristic changes mean changes from pre-operation to postoperation.
Values were adjusted for age, sex, body mass index, diabetes history, urolithiasis history, renal colic, history of fever, maximum stone diameter, stone burden and site, surgical lateral, number of tracts, operation time, surgical year and surgeon with multivariable logistic or linear regressions. Beta coefficient ratios were calculated for continuous variables with linear regression and rate ratios were calculated for categorical variables with logistic regression.
CI, confidence interval; eGFR, estimated glomerular filtration rate; IQR, interquartile range; WBC, white blood cell.
Safety outcomes
The results of safety analyses generally suggested that balloon dilatator use was safer than metallic telescopic dilatator use. The respective changes in hemoglobin levels after surgery relative to preoperative levels in the balloon and the metallic telescopic groups were −6 g/L (IQR, −17 to 3) and −13 g/L (IQR, −24 to −5), respectively (beta coefficient ratio, 7.19; 95% CI, 5.68–8.70, Table 2); blood transfusion rates were 0.5% and 1.5% (RR, 0.33; 95% CI, 0.12–0.93); renal artery embolization hemostasis rates were 1.6% and 3.2% (RR, 0.44; 95% CI, 0.24–0.81); and kidney resection rates were 0.3% and 0.7% (RR, 0.62; 95% CI, 0.16–2.46). Subgroup analyses indicated that hemoglobin changes tended to be better in the balloon dilation group relative to most subgroups (Figure 2). Subgroup analyses of blood transfusion, renal artery embolism, and operative duration outcomes are presented in Supplemental Figures 4–6.
Subgroup analyses of postoperative changes in hemoglobin relative to preoperative baseline. Adjusted beta coefficients and corresponding 95% confidence intervals are presented for postoperative changes in hemoglobin relative to preoperative values in subgroups that had been prespecified. A multivariate linear regression approach was used to calculate beta coefficients for the balloon group relative to the metallic telescopic group with adjustment for age, sex, body mass index, history of diabetes, history of urolithiasis, renal colic, history of fever, maximum stone diameter, stone burden and site, surgical laterality, number of tracts, operative duration, year of surgery, and surgeon.
Economic benefit outcome
The duration of hospitalization in the balloon and metallic telescopic groups was 9 days (IQR: 6–12) and 12 days (IQR: 10–15), respectively (beta coefficient ratio, −2.32; 95% CI, −2.81 to −1.84, Table 2). Surgical and postoperative costs in these respective groups were 18 thousand yuan (IQR: 13–24) and 15 thousand yuan (IQR: 11–19) (beta coefficient ratio, 2.36; 95% CI, 1.71–3.02). Subgroup analyses of hospitalization duration and costs are presented in Supplemental Figures 7–9.
Discussion
This was a retrospective analysis of 2269 patients with urinary tract stones who underwent PCNL, of whom 1222 and 1047, respectively, underwent procedures using balloon dilatators and metallic telescopic dilatators for tract establishment. No significant differences between these two groups were observed in terms of overshooting, failure of access, and stone-free rates. A study comparing tract dilation in ultrasound-guided percutaneous nephrolithotomy has shown that the success rate of the first attempt at urethral dilation was 87.4% for the balloon dilatators group, which was slightly lower when compared with 95.8% for the metallic telescopic dilatators group, 13 but this difference was not statistically significant (p = 0.054). This finding is in line with our research, which also indicated no significant difference between the two groups in terms of failure of access. The results of a randomized clinical trials comparing Amplatz versus balloon for tract dilation in ultrasonographically guided percutaneous nephrolithotomy showed that balloon dilation had a higher success rate than Amplatz dilation (87.9% in balloon dilatators group and 84.8% in metallic telescopic dilatators group (p = 0.19)), 14 due to the fact that Amplatz had a higher short dilation rate than balloon dilation. During ultrasonographically guided PCNL, the instruments are less visible than fluoroscopy-guided PCNL; thus, the Amplatz dilator may push the kidney and not enter the calyx. This state is called “short” dilation. In our study, there was no significant difference in the success rate of channel dilation between metallic telescopic dilators and balloon dilators, which may be related to the similar short dilation rate of metallic telescopic dilators and balloon dilators during dilation. Meanwhile, in terms of cost comparison, balloon dilators are higher than Amplatz dilators and metallic telescopic dilators. The procedure costs of this study did not include preoperative bed fees and examination and testing costs for patients. Only surgical fees and postoperative expenses were calculated. When the initial tract establishment failed, we attempted to re-establish the tract, and all cases were successfully dilated after 1–2 additional attempts. The patients exhibited better safety outcomes, including a lower postoperative reduction in hemoglobin levels (6 vs 13), fewer instances of blood transfusion (0.5% vs 1.5%), and a reduced incidence of postoperative renal artery embolism relative (1.6% vs 3.2%) to the metallic telescopic group. Economic benefit analyses indicated that balloon dilation was associated with a shorter duration of hospitalization (9 vs 12) relative to metallic telescopic dilation, although this benefit came with higher overall hospitalization costs. Subgroup analyses supported the overall results of this study, emphasizing the robust nature of these conclusions.
Several confounding factors have the potential to impact stone-free rates, including stone burden, number of tracts, operative duration, and the skill of the operating surgeon.1,15,16 Prior studies have not fully adjusted for all these factors, instead only correcting for a subset thereof, ultimately contributing to different conclusions.5,8–11 In this study, patients were grouped based on the surgeon’s experience, and the overall sample size was larger than that reported in previous studies. Recognizing that factors contributing to heterogeneity vary among clinical studies, we used multivariate logistic regression or linear regression methods to adjust for factors identified in the baseline data of this study, to minimize variability, ensure that they would not affect the final results, and obtain reliable conclusions. The results showed no significant difference in the stone-free rate between these two surgical methods.
Bleeding is a key consideration when evaluating the safety of a surgical procedure. Interaction analyses revealed a correlation between the overshooting (beta coefficient ratio, 2.41; 95% CI, 2.22–2.61) and failure of access (beta coefficient ratio, 2.81; 95% CI, 2.52–3.10) rates in hemoglobin levels. Since there was no statistical difference in overshooting and failure of access rates between the two groups, the difference in hemoglobin between the two groups was not due to differences in their incidence rates. One retrospective study reported that balloon dilation was associated with a higher risk of blood transfusion, but the high degree of heterogeneity among patients in that study emphasizes a need for caution when interpreting the results. 11 In the present study, balloon dilation was associated with better outcomes in terms of the control of bleeding relative to metallic telescopic dilation, as evidenced by differences in the reduction in hemoglobin levels, transfusion rates, and renal artery embolism rates. The nephrectomy rate reported in this study refers to the proportion of unilateral nephrectomies performed during PCNL, with all nephrectomies being conducted due to excessive intraoperative bleeding. In previous studies, 17 the nephrectomy rate after PCNL was 0.2%. In our study, the nephrectomy rate for the balloon dilatators group was 0.3%, and for the metallic telescopic dilatators group, it was 0.7%. While a trend toward a better postoperative nephrectomy rate was observed in the balloon group, the difference was not significant. In this study, all patients who underwent nephrectomy did so due to excessive bleeding, and nephrectomy was the only means to achieve hemostasis. The difference in kidney removal rates due to bleeding may be related to the more rigid material of metal dilators compared to balloon dilators. Improvements in perioperative hemostatic techniques have contributed to annual decreases in nephrectomy rates. Further studies will thus be important to clarify whether these two dilation approaches are truly associated with any difference in nephrectomy rate.
The ability of the balloon-based dilation approach to control blood loss more effectively than the metallic telescopic method may be related to the issue of metal expansion. 18 The expansion of metal can result in a brief loss of pressure acting on the blood vessels, thereby weakening the renal parenchymal filling effect. Previous studies have compared the changes in hemoglobin levels before and after surgery, as well as the bleeding rates, between Amplatz dilation and one-shot dilation, and the results showed no difference. This led us to rule out the possibility that the friction associated with removing each dilator when using the Amplatz dilator could cause bleeding. Such excessive renal displacement is likely to result in severe vascular damage, potentially leading to massive bleeding. Balloon dilation procedures instead rely on lateral dilation along the vertical direction of the renal pelvis, using a balloon to compress the blood vessels proximal to the channel to achieve hemostasis, which should theoretically protect against the rupture of blood vessels and associated bleeding.18,19 From another perspective, the balloon material exhibits greater elasticity, providing excellent conformal characteristics when it expands and comes into contact with muscles and blood vessels. This results in a larger contact area and more uniform force distribution, thereby causing less damage. Conversely, due to their rigid nature, metallic devices are more likely to cause severe trauma to the passageway during dilation. The balloon-based method is also associated with a shorter operative duration for the treatment of stones as compared to the metallic telescopic dilation. Previous studies have indicated that there is no significant difference in procedure time between balloon dilation and Amplatz dilation.7,10 However, the findings of these studies are consistent with ours: in our study, the average procedure time in the balloon dilatators group was 80 min, which was shorter than the 90 min in the metallic telescopic dilatators group.5,6 This may be because the balloon dilation method can create an appropriate lumen in one step without the need for sequential dilation. Interaction analyses revealed a correlation between the operative duration and postoperative changes in hemoglobin levels (beta coefficient ratio, −1.07; 95% CI, −1.75 to −0.39), which may also be related to the difference in bleeding between these groups.
No significant differences in postoperative renal function or infection control were observed when comparing the balloon and metallic telescopic methods, with no postoperative differences in postoperative WBC counts or creatinine levels between the two.
In preliminary economic analyses, the hospitalization recovery time associated with balloon surgery was shorter than that for metallic telescopic surgery, allowing patients to more quickly resume their normal lives. Interaction analyses also revealed a correlation between the duration of hospitalization and changes in hemoglobin levels (beta coefficient ratio, −0.34; 95% CI, −0.48 to −0.19). Balloon dilation may thus require a shorter period of postoperative observation in the hospital owing to lower levels of postoperative blood loss. As balloon dilatators are more expensive than metallic telescopic dilatators, the overall hospitalization costs and only procedure costs for balloon dilation procedures were still higher than those for metallic telescopic dilation. However, differences in the costs of brands of balloon dilatators underscore a need for additional research aimed at validating this finding and assessing its generalizability.
The primary limitation of this study is the retrospective nature of its design, limiting the reliability of these conclusions as compared to findings from clinical trials. This was also a single-center study that enrolled patients from a particular region, such that the findings may not be more broadly representative. In addition, this study included patients from a 10-year timespan (2011 to 2021), and advances in surgical techniques, rising levels of surgical experience, and fluctuating equipment prices may have influenced the results. While efforts were made to adjust for confounding factors, these variables will inevitably have impacted the results of this study.
Conclusion
Both balloon dilation and metallic telescopic dilation achieve similar overshooting, failure of access, and stone-free rates when used for the ultrasound-guided PCNL-based treatment of urolithiasis, but balloon dilation is associated with less severe bleeding and a shorter duration of hospitalization relative to metallic telescopic dilation. When not taking costs into account, balloon dilation offers clear advantages over metallic telescopic dilation.
Supplemental Material
sj-pdf-1-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-1-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-2-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-2-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-3-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-3-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-4-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-4-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-5-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-5-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-6-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-6-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-7-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-7-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-8-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-8-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Supplemental Material
sj-pdf-9-tau-10.1177_17562872251372210 – Supplemental material for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study
Supplemental material, sj-pdf-9-tau-10.1177_17562872251372210 for The relative performance of balloon dilatators and metallic telescopic dilatators for the establishment of ultrasound-guided percutaneous nephrolithotomy tracts: a single-center, retrospective study by Shangjing Liu, Yuchen Qian, Zhenguo Wang, Qingzuo Liu, Peng Zhang, Yining Zhao and Jitao Wu in Therapeutic Advances in Urology
Footnotes
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
