Percutaneous Nephrolithotomy Use Is Increasing in the United States: An Analysis of Trends and Complications

Conservative Management of a Biliary Tract Injury During Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy (PCNL) is a well-established treatment option for the management of kidney stones. It has evolved over time with advances in surgical technique and technology. Even for the most experienced urologists, both major and minor complications may be encountered during PCNL. Timely diagnosis and appropriate management are the keys to a favourable outcome. Here, we discuss the case of a woman aged 34 years, who underwent PCNL for a right renal staghorn stone and had an accidental puncture of the gall bladder. Post-operatively, the patient recovered well with conservative management.

Predictive values of the SOFA score and procalcitonin for septic shock after percutaneous nephrolithotomy

To investigate the value of combination of the Sequential Organ Failure Assessment (SOFA) score and procalcitonin (PCT) for prediction of septic shock after percutaneous nephrolithotomy (PCNL). A total of 1328 patients receiving PCNL for renal calculi were allocated into control group (without septic shock) and septic shock group, and related data were retrospectively collected. Univariate analysis was firstly performed, and the variables with two sided P < 0.10 were then included in logistic regression analysis to determine independent risk factors. Receiver operating characteristic (ROC) curve was utilized to evaluate the predictive values. Area under curve (AUC) was compared using Z test. Postoperative septic shock was developed in 61 patients (4.6%) and not developed in 1267 patients (95.3%). Multivariate analysis demonstrated that SOFA score (OR: 1.316, 95% CI 1.125–1.922), PCT (OR: 1.205, 95% CI 1.071–1.696) and operative time (OR: 1.108, 95% CI 1.032–1.441) were independent risk factors for septic shock with adjustment for sex, history of urolithiasis surgery, positive history of urine culture and history of PCNL. The ROC curves demonstrated that the AUCs of SOFA score and PCT for predicting septic shock after PCNL were 0.896 (95% CI 0.866–0.927) and 0.792 (95% CI 0.744–0.839), respectively. The AUC of their combination was 0.971 (95% CI 0.949–0.990), which was higher than those of individual predictions (vs 0.896, Z = 4.086, P < 0.001; vs 0.792, Z = 6.983, P < 0.001). Both the SOFA score and PCT could be applied in predicting septic shock after PCNL, and their combination could further elevate the diagnostic ability.

Postoperative infective complications following percutaneous nephrolithotomy

Introduction

Percutaneous nephrolithotomy (PCNL) is recommended as the first choice of therapeutic strategy for patients with renal stones larger than 2 cm. It is reported that up to one-third of patients might have some perioperative complications, especially fever and urinary tract infections, which constitutes about 21%-39.8% of all the complications.

Primary and Secondary

The primary aim of the study was to study about the proportion of patients getting post-operative infective complications following PCNL. The secondary aim was to study the patient, stone and procedure related risk factors associated with the infective complications.

Settings and Design

This is an institution-based observational study.

Materials and Methods

All patients who underwent PCNL in the Department of Urology, Medical College, Thiruvananthapuram, during 3 years from September 2016- to August 2019, were included in the study. In this study, the demographic factors and factors related to the patient, stone, and the procedure were collected and analyzed.

Statistical Analysis Used

Data analysis was performed using SPSS version 22.0.

Results

During the 3-year period, a total of 201 patients with renal stones were treated with PCNL in our hospital. Of this 190 cases were taken for analysis. The mean age of patients was 47.7 years, 148 (77.9%) were male, 42 (22.1%) were female, The final outcomes evaluated were episodes of fever, documented urinary tract infection (UTI), pyelonephritis, and sepsis. Thirty-six (18.9%) patients had fever, of which 21 (11.1%) had UTI, 6 (3.1%) had pyelonephritis and 5 (2.6%) developed sepsis.

Conclusions

Post-PCNL complications are more commonly found in patients with history of preoperative UTI, previous history of renal surgeries, large stone burden, operative procedure more than 90 min, and presence of residual calculi.

Visualization of the renal vein filled with contrast agent may indicate the renal vein injury during percutaneous nephrolithotomy: two case reports

Background

Intravenous misplacement of a nephrostomy tube is a rare complication of percutaneous nephrolithotomy (PCNL) or percutaneous nephrostomy. The mechanism of misplacement of a nephrostomy tube into the vascular system is seldom investigated. One type of the possible mechanism is that the puncture needle penetrates a major intrarenal tributary of the renal vein and enters the collecting system. However, the guidewire is located outside the collecting system near the large branches of renal vein or perforates into the renal vein. The dilation is performed and causes a large torn injury. Subsequently, the nephrostomy tube is placed inside the vessel when radiological monitoring is not used. However, there is no imaging evidence and the scene of procedure is not demonstrated. This paper reports two cases of visualization of the renal vein filled with contrast agent during PCNL. The findings may be good evidence to support the step of renal vein injury in patients with intravenous nephrostomy tube misplacement.

Case presentation

We presented two cases with visualization of the renal vein filled with contrast agent during PCNL. In the process of injecting the contrast agent through the puncture needle, we could see the renal vein. Moreover, it was identified that the puncture needle tip was not on the optimal position. The position of puncture needle tip lay outside the collecting system, which was close to the calyceal infundibulum and branches of renal vein.

Conclusions

Visualization of the renal vein filled with contrast agent may be good evidence to verify the renal vein injury in patients with intravenous nephrostomy tube misplacement during PCNL or percutaneous nephrostomy. The suboptimal location of the puncture needle tip and visualization of the renal vein filled with contrast agent indicate the renal vein injury. One type of mechanism of intravenous nephrostomy tube misplacement is as following. Firstly, the guidewire stays outside the collecting system. Subsequently, dilatation directed by the guidewire results in the injury of the vein. Then, the nephrostomy tube migrates into the venous system due to prompt tube inserting and the direction of the sheath and/or the guidewire to the injured vein.

Nationwide Trends in Tube-Related Genitourinary Interventions for Medicare Beneficiaries

PURPOSE

To evaluate national trends in tube-related genitourinary interventions, with specific attention to primary operator specialty.

METHODS

Using a 5% national sample of Medicare claims data from 2005 to 2015, all claims associated with nephrostomy tube, nephro-ureteral tube, and ureteral stent placement and exchange were identified. The annual volume of the nine billable procedures were analyzed to evaluate trends in the number of procedures performed and primary operator specialty over time. The Charleston Comorbidity Index (CCI) was used to evaluate patient comorbidities and to determine differences in patient populations treated by interventional radiologists and urologists.

RESULTS

The total volume of tube-related genitourinary interventions has increased over the course of the study period, representing 455.0 services per 100,000 Medicare Fee-for-Service beneficiaries in 2005 to 607.2 services in 2015, an increase of 33.4%. Interventional radiologists performed the majority of all procedures in all procedure types and for each year (>90%) with the exception of nephro-ureteral catheter placement or ureteral stent placement, for which urologists performed the overwhelming majority of procedures each year (>85%). Interventional radiologists performed 63% of their total number of procedures on patients with a CCI = 3 or higher, and urologists performed 42% of their total number of procedures on patients with a CCI = 3 or higher (P < .01).

CONCLUSION

Tube-related genitourinary interventions have demonstrated persistent growth over the 2005 to 2015 decade. Interventional radiologists are the dominant providers for the majority of these interventions compared with urologists while delivering care to a patient population with a higher number of comorbidities.

Performance of SOFA, qSOFA and SIRS to predict septic shock after percutaneous nephrolithotomy

OBJECTIVE

The new clinical criteria termed SOFA and qSOFA were demonstrated to be more accurate than SIRS in screening patients at high risk of sepsis. We aim to evaluate the ability of SOFA, qSOFA and SIRS to predict septic shock after PCNL.

PATIENTS AND METHODS

Consecutive patients undergoing PCNL were included to assess the performance of SOFA, qSOFA and SIRS in predicting septic shock, the AUC of ROC curve and decision curve analysis were used, and the optimal cutoff values and their achieving time were calculated.

RESULTS

Of the 431 included patients, 12 (2.7%) cases developed septic shock. Compared with non-septic shock patients, patients with septic shock were more likely to be female, have positive history of urine culture and higher urine leukocyte count, and show increased postoperative serum creatinine, PCT and decreased leukocyte. The optimal cutoff of SOFA, qSOFA and SIRS was > 2, > 0 and > 1, respectively. All of the 12 patients with verified septic shock met SOFA and SIRS criteria, while only 11 cases met qSOFA criterion. SOFA had the identical highest sensitivity (100%) and greater specificity (87% vs. 81%) than SIRS. qSOFA had higher specificity (92%) than both SOFA and SIRS at the expense of lower sensitivity (92%). The AUC of SOFA (0.973) to predict septic shock was greater than that of qSOFA (0.928) and SIRS (0.935). When combined with SIRS, SOFA outperformed qSOFA for discrimination of septic shock (AUC 0.987 vs. 0.978). Decision curve analysis indicated SOFA was clearly superior to both qSOFA and SIRS with a higher net benefit and net reduction in intervention. The qSOFA achieved the best time-based predictive efficiency, with the shortest median time to meet its cutoff, followed by SOFA and SIRS.

CONCLUSION

The performance of SOFA in predicting septic shock after PCNL was slightly greater than qSOFA and SIRS. The comprehensive application of various criteria is recommended to assist early detection of septic shock following PCNL.

Initial Clinical Experience with Swiss LithoClast Trilogy During Percutaneous Nephrolithotomy

Introduction and Objective: Current available lithotrites have clinical stone clearance rates averaging 24 to 32 mm²/minute. The objective of this study was to critically evaluate the initial experience with the Swiss LithoClast^® Trilogy lithotrite during percutaneous nephrolithotomy (PCNL). Methods: We prospectively enrolled patients with a minimum of 15 mm of stone in axial diameter at three locations (Indiana University, University of California Davis, and University of California San Diego) scheduled to undergo PCNL for nephrolithiasis over a 60-day trial period. We assessed objective measures of stone clearance time, stone clearance rate, device malfunction, stone-free rate, and complications. Each surgeon also evaluated subjective parameters from each case related to the use of Trilogy on a 1 to 10 scale (10 = extremely effective), and compared it with their usual lithotrite on a 1 to 5 scale (5 = much better). Results: We included 43 patients and had 7 bilateral (16.3%) cases, for a total of 50 renal units. One case was a mini-PCNL. Two cases experienced device malfunctions requiring troubleshooting but no transition to another lithotrite. The mean stone clearance rate was 68.9 mm²/minute. The stone-free rate on postoperative imaging was 67.6% (25 of 37 patients with available imaging). The lowest subjective rating was the ergonomic score of 6.7, and the highest subjective rating was the ease of managing settings score of 9.2. The surgeon impressions of ultrasound (7.3), ballistics (8.1), combination of ultrasound and ballistics (8.7), and suction (8.4) were high. One patient experienced an intraoperative renal pelvis perforation, one patient required a blood transfusion, one patient had a pneumothorax requiring chest tube placement, and one patient had a renal artery pseudoaneurysm requiring endovascular embolization. Conclusions: This multi-institutional study evaluated a new and efficient combination lithotrite that was perceived by surgeons to be highly satisfactory, with an excellent safety and durability profile.

The evolution of percutaneous nephrolithotomy: Analysis of a single institution experience over 25 years

INTRODUCTION

Over time, the incidence of nephrolithiasis has risen significantly, and patient populations have become increasingly complex. Our study aimed to determine the impact of changes in patient demographics on percutaneous nephrolithotomy (PCNL) outcomes.

METHODS

A retrospective analysis of a prospectively collected database was carried out from 1990-2015. Patient demographics, comorbidities, stone and procedure characteristics were analyzed. Multivariate logistic regression was used to evaluate differences in operative duration, complications, stone-free rate, and length of stay.

RESULTS

A total of 2486 patients with a mean age of 54±15 years, body mass index (BMI) of 31±8, and stone surface area of 895±602 mm² were analyzed; 47% of patients had comorbidities, including hypertension (22%), diabetes mellitus (14%), and cardiac disease (13%). Complication rate was 19%, including a 2% rate of major complications (Clavien grade III-V). There was a statistically significant increase in patient age, BMI, and comorbidities over time, which was correlated with an increased complication rate (odds ratio [OR] 1.15; p=0.010). The overall transfusion rate was 1.0% and remained stable (p=0.131). With time, both OR duration (mean Δ 16 minutes; p<0.001) and hospital length of stay (mean Δ 2.4 days; p<0.001) decreased significantly. Stone-free rate of 1873 patients with available three-month followup was 87% and decreased significantly over time (OR 1.09; p<0.001), but was correlated with an increased use of computed tomography (CT) scans for followup imaging.

CONCLUSIONS

Despite an increasingly complex patient population, PCNL remains a safe and effective procedure with a high stone-free rate and low risk of complications.

Increasing stone complexity does not affect fluoroscopy time in percutaneous nephrolithotomy

Background:

The aim of this work was to assess whether stone complexity with the Guy’s stone score (GSS) is associated with increased intraoperative fluoroscopy time.

Methods:

We retrospectively reviewed records of 261 consecutive patients undergoing percutaneous nephrolithotomy between 2007 and 2015. Of these, 203 had both preoperative computed tomography for accurate staging and full intraoperative fluoroscopy and radiation dosimetry data were available. Stone complexity was assessed using GSS. A correlation between fluoroscopy time (FT) and GSS was assessed in a univariate and multivariate fashion, including parameters such as age, sex, body mass index (BMI), and number of accesses.

Results:

The overall mean FT was 3.69 min [standard deviation (SD) 2.77]. The overall mean Guy’s score was 2.5 (SD 1). There was a statistically significant correlation between operative time and FT (r = 0.34, p < 0.0001). There was a trend towards increasing operative time with increasing GSS (r = 0.12, p = 0.08), but there was no statistically significant correlation. There was no correlation between FT and GSS (r = 0.04, p = 0.55). On multivariable regression, accounting for sex, BMI, age, and singular versus multiple accesses, there was no significant correlation between stone complexity and FT (p = 0.893).

Conclusions:

In the setting of conscious efforts to reduce intraoperative radiation exposure, increasing stone complexity, as classified by GSS, did not correlate with FT on univariate or multivariate analysis. Thus, treatment of more complex stones may be undertaken without concern that there is an inevitable need for significantly increased fluoroscopy exposure to the patient or operating room staff.

Subcapsular Splenic Urinoma and Splenorenal Fistula: A New Complication of Percutaneous Nephrolithotomy

Background: Splenic urinoma has not been previously reported as a complication of percutaneous nephrolithotomy (PNL). Case Presentation: A 46-year-old Caucasian male underwent PNL for two large left renal stones. Surgery was performed in prone split-leg position, with access obtained through combined fluoroscopic guidance and direct ureteroscopic observation of the targeted calix. The tract was dilated to 30F using a pressure balloon, and complete clearance of stones was obtained through a combination of rigid and flexible nephroscopy, as well as antegrade ureteroscopy. The patient was left with a Double-J ureteral stent on a string for removal in 1 week. After overnight observation, his hemoglobin, white blood cell count, and renal function were normal and thus he was discharged home. The day after stent removal, he presented to the emergency department with abdominal pain, was found to have mild left hydronephrosis on CT, and was discharged on 1 week of antibiotics. One week later he re-presented with worsening abdominal pain and was found to have an elevated creatinine and a white blood cell count of 21 × 10⁹/L. On contrasted CT with delayed images, an 18 cm splenic fluid collection was seen with a fistulous connection to the left kidney collecting system. He underwent emergent stent placement and improved clinically without drainage of the urinoma. A renal ultrasonography 1 month after stent placement confirmed resolution of the splenic urinoma, so the stent was removed at 1 month. Follow-up CT 1 month after stent removal was normal without any evidence of fistula or urinoma recurrence. Conclusion: This is the first report of a subcapsular splenic urinoma and splenorenal fistula post-PNL. Ureteral stent placement was sufficient for drainage and to resolve the complication.

Is standard percutaneous nephrolithotomy still the standard treatment modality for renal stones less than three centimeters?

OBJECTIVE

The aim of study was to compare the efficiency and safety of standard percutaneous nephrolithotomy (sPNL) and miniaturized percutaneous nephrolithotomy (mPNL) in lower calyx and/or pelvic stones smaller than three centimeters.

MATERIAL AND METHODS

From October 2010 to August 2015, 108 mPNL and 176 sPNL procedures were performed for renal stones smaller than three cm and located in the lower calyx and/or renal pelvis. All patients were evaluated preoperatively with intravenous pyelography and/or computed tomography. Intraoperative parameters, post-operative results and complications were recorded. Postoperative success was defined as complete stone clearance and/or clinically insignificant residual fragments at 3^rd month.

RESULTS

Preoperative characteristics were similar between sPNL and mPNL groups except previous renal stone operation history and gender. The mean operation time was significantly shorter in the sPNL group (p<0.001). The mean hemoglobin drop was significantly less in the mPNL group (p=0.001), we found a 1.27±1.4 and 0.5±1.3 decrease in mean hemoglobin levels (mg/dL) in the sPNL and mPNL groups, respectively. Transfusion rate was 1.9% in mPNL and 5.6% in sPNL groups, and the difference was statistically significant (p=0.048). Only one patient in the sPNL group needed angiography and embolization. Postoperative JJ stent insertion rate was significantly higher in the mPNL group (p=0.03).

CONCLUSION

Both sPNL and mPNL are safe and effective surgical procedures for lower calyx and/or pelvis stones smaller than 3 cm. However, use of smaller caliber instruments was associated with a lesser hemoglobin drop and need for transfusion.

The Evaluation of Risk Factors for Postoperative Infectious Complications after Percutaneous Nephrolithotomy

This study was to evaluate the risk factors of infectious complications after percutaneous nephrolithotomy (PCNL) and build a prediction tool for postoperative complications based on the risk factors. A total of 110 male (67.1%) and 54 female (32.9%) patients who underwent PCNL for renal stones between 2010 and 2014 in our institute were included. A detailed clinical information and laboratory results were obtained from patients. Systemic inflammatory response syndrome (SIRS) and postoperative fever were recorded after PCNL surgery. In all, 45 cases (27.4%) developed SIRS and fever was observed in 20 cases (12.2%). In multivariate analysis, stone size (odds ratio, OR = 1.471, p = 0.009) and urine white blood cell (WBC) (OR = 1.001, p = 0.007) were related to the development of SIRS. Stone size (OR = 1.644, p = 0.024), urine WBC (OR = 1.001, p = 0.002) and serum albumin (OR = 0.807, p = 0.021) were associated with postoperative fever. We concluded that patients with larger stone size and preoperative urinary tract infection might have a higher risk of developing SIRS and fever after operation, while a high-normal level of serum albumin might be the protective factor for postoperative fever.

Implications of different nephrolithometry scoring systems on clinical practice of endourologists: An international web-based survey

OBJECTIVES

To assess the implications of different nephrolithometry scoring systems (NLSS) on clinical practice of endourologists to predict stone-free status (SFS) after percutaneous nephrolithotomy (PCNL).

METHODS

A web-based survey was sent to members of the Endourological Society. Demographic and practice pattern data were collected. Multiple-choice and open-ended questions were used to assess awareness about the NLSS and their authentic use in clinical practice. Surgeon preferences and limitations of NLSS and how to overcome them were asked.

RESULTS

In all, there were 162 responses, including 17 (10.5%) respondents who were not aware of NLSS. Most respondents (82.1%) denied the efficacy of NLSS in predicting SFS after PCNL. Of 145 respondents who were aware of NLSS, 85.5% did not use them in clinical practice. Endourologists aged 40-60 years (P < 0.001), in practice for 10-20 years (P = 0.003), those performing 100-200 PCNLs/year (P = 0.02), and those from North America (P < 0.001) seemed to use NLSS more frequently. In all, 50% of respondents preferred not to use any NLSS, while 29% chose the S.T.O.N.E followed by the Guy's Stone Score (10.3%) and The Clinical Research Office of the Endourology Society (CROES) nomogram (8.3%). Inconsistency and variability among different NLSS were the main drawbacks reported by 82% of 89 respondents. The need for high-level evidence for NLSS through direct randomised prospective comparison was recommended by 24.8% of respondents who answered that question.

CONCLUSION

There is a lack of compliance and acceptance of different NLSS in clinical practice among endourologists. Inconsistency and inaccuracy in predicting SFS after PCNL limits their incorporation into clinical practice. However, the results of this study might not be generalisable due to the selection bias resulting from the geographical distribution of the respondents and the heterogeneity in surgical expertise. Therefore, randomised prospective direct comparisons and validation of these systems are recommended.

Multicenter External Validation and Comparison of Stone Scoring Systems in Predicting Outcomes After Percutaneous Nephrolithotomy

BACKGROUND AND PURPOSE

Several scoring systems have recently emerged to predict stone-free rate (SFR) and complications after percutaneous nephrolithotomy (PCNL). We aimed to compare the most commonly used scoring systems (Guy's stone score, S.T.O.N.E. nephrolithometry, and CROES nomogram), assess their predictive accuracy for SFR and other postoperative variables, and develop a risk group stratification based on these scoring systems.

MATERIALS AND METHODS

We performed a retrospective review of patients who have had a PCNL at four academic institutions between 2006 and 2013. Primary outcome was SFR within 3 weeks of the surgery and secondary outcomes were operative time (OT), complications, and length of stay (LOS). We performed chi-squared, t-test, logistic, linear, and Poisson regressions, as well as receiver operating characteristics curve with area under the curve (AUC) calculation.

RESULTS

We identified 586 patients eligible for analysis. Of these, 67.4% were stone free. Guy's, S.T.O.N.E., and CROES score were predictive of SFR on multivariable logistic regression (odds ratio [OR]: 1.398, 95% confidence interval [CI]: 1.056, 1.852, p = 0.019; OR: 1.417, 85% CI: 1.231, 1.631, p < 0.001; OR: 0.993, 95% CI: 0.988, 0.998, p = 0.004) and have similar predictive accuracy with AUCs of 0.629, 0.671, and 0.646, respectively. On multivariable linear regression, only S.T.O.N.E. was an independent predictor of longer OT (β = 14.556, 95% CI: 12.453, 16.660, p < 0.001). None of the scores were independent predictors of postoperative complications or a longer LOS. Poisson regression allowed for risk group stratification and showed the S.T.O.N.E. score and CROES nomogram to have the most distinct risk groups.

CONCLUSIONS

The three evaluated scoring systems have similar predictive accuracy of SFR. S.T.O.N.E. has additional value in predicting OT. Risk group stratification can be used for patient counseling. Further research is needed to identify whether or not any is superior to the others with regard to clinical usefulness and predictive accuracy.

The Cost-Effectiveness of Treatment Modalities for Ureteral Stones

Additional intervention and medical treatment of complications may follow the primary treatment of a ureteral stone. We investigated the cost of the treatment of ureteral stone(s) within 45 days after initial intervention by means of retrospective analysis of the National Health Insurance Research Database of Taiwan. All patients of ages ≥20 years diagnosed with ureteral stone(s)( International Classification of Diseases, Ninth Revision, Clinical Modification/ICD-9-CM: 592.1) from January 2001 to December 2011 were enrolled. We included a comorbidity code only if the diagnosis appeared in at least 2 separate claims in a patient’s record. Treatment modalities (code) included extracorporeal shock-wave lithotripsy (SWL; 98.51), ureteroscopic lithotripsy (URSL; 56.31), percutaneous nephrolithotripsy (PNL; 55.04), (open) ureterolithotomy (56.20), and laparoscopy (ie, laparoscopic ureterolithotomy; 54.21). There were 28 513 patients with ureteral stones (13 848 men and 14 665 women) in the randomized sample of 1 million patients. The mean cost was 526.4 ± 724.1 United States Dollar (USD). The costs of treatment were significantly increased in patients with comorbidities. The costs of treatment among each primary treatment modalities were 1212.2 ± 627.3, 1146.7 ± 816.8, 2507.4 ± 1333.5, 1533.3 ± 1137.1, 2566.4 ± 2594.3, and 209.8 ± 473.2 USD in the SWL, URSL, PNL, (open) ureterolithotomy, laparoscopy (laparoscopic ureterolithotomy), and conservative treatment group, respectively. In conclusion, URSL was more cost-effective than SWL and PNL as a primary treatment modality for ureteral stone(s) when the possible additional costs within 45 days after the initial operation were included in the calculation.

Value of preoperative stone scoring systems in predicting the results of percutaneous nephrolithotomy

INTRODUCTION

Guy's Stone Score and S.T.O.N.E. Nephrolithometry nomograms have been introduced for systematic and quantitative assessment of kidney stones. The aim of this study was to reveal the value of two scorings systems, Guy and S.T.O.N.E, most frequently used for predicting postoperative stone-free status prior to Percutaneous Nephrolithotomy (PCNL), in the prediction of postoperative results of PCNL.

MATERIAL AND METHODS

We retrospectively examined patients who underwent PCNL. Preoperative abdominopelvic computerized tomography images of these patients were reviewed and scored according to the Guy and S.T.O.N.E. systems. The relationship between the Guy and S.T.O.N.E. scores, and their postoperative stone-free status, complications based on Clavien system, operation time, fluoroscopy time and period of hospitalization was compared.

RESULTS

We identified a total of 102 patients who underwent PCNL between 2010 and 2014, having met the inclusion criteria. The relationships between the total S.T.O.N.E score and Clavien score (p <0.001); time of operation (p = 0.012) and stone-free status (p <0.001); Guy stone score and Clavien score (p <0.001); and period of hospitalization (p <0.001) and time of operation (p <0.001) were found to be statistically significant. There was no statistically significant relationship between Guy score and stone-free status and no statistically significant relationship was found between fluoroscopy time and both stone scoring systems.

CONCLUSIONS

Guy and S.T.O.N.E. scoring systems may be used as effective instruments particularly for predicting postoperative complications.

Statin Use and Risk of Sepsis After Percutaneous Nephrolithotomy

PURPOSE

To examine the association between statin medication use and sepsis risk after percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

Using medical claims data, we identified working-age adults with urinary stone disease who were treated with PCNL. Among this cohort, we determined which patients had a prescription fill for a statin agent that encompassed their surgery date. We then fitted logistic regression models to examine for differences in rates of postoperative sepsis between statin users and nonusers. In addition, we evaluated the frequency of nonfebrile urinary tract infections (UTIs) and intensive care unit (ICU) services utilization and hospital length of stay (LOS) as a function of statin use.

RESULTS

During the study period, at total of 2046 patients underwent PCNL, 382 (18.7%) of whom had a prescription fill for a statin agent preceding their surgery. The overall rate of sepsis in this population was 3.8%. After adjusting for patient health status and sociodemographic factors, the rate of postoperative sepsis was comparable between statin users and nonusers (5.3% vs 3.5%, respectively; P=0.105). In addition, UTI and ICU utilization rates did not relate to statin use (P>0.05 for all associations). Adjusted hospital LOS was shorter among statin users, but the difference was clinically trivial (3.6 vs 4.1 days; P=0.007).

CONCLUSIONS

Statin use is not associated with reductions in postoperative sepsis, nonfebrile UTIs, ICU utilization, or hospital LOS after PCNL. To increase the safety of PCNL, urologists will have to consider other processes of care (e.g., clinical care pathways).

Intravenous misplacement of nephrostomy tube following percutaneous nephrolithotomy: Three new cases and review of seven cases in the literature

PURPOSE

We investigated the characteristics and management of patients with intravenous misplacement of a nephrostomy tube.

MATERIALS AND METHODS

Between July 2007 and July 2013, 4148 patients with urolithiasis underwent percutaneous nephrolithotomy (PCNL) in our hospital. Intravenous misplacement of a nephrostomy tube occurred in two of these patients. Another patient with intravenous misplacement of a nephrostomy tube, who underwent PCNL in another hospital, was transferred to our hospital. The data of the three patients were retrospectively analyzed.

RESULTS

The incidence of intravenous misplacement of a nephrostomy tube following PCNL was 0.5% (2/4148) at our hospital. A solitary kidney was present in one of the three patients. The tip of tube was located into the inferior vena cava (IVC) in two patients and into the renal vein in one patient. All three patients were successfully managed with strict bed rest, intravenous antibiotics and one-step (one patient) or two-step (two patients) tube withdrawal under close monitoring. None of the patients underwent antithrombotic therapy. The original operations were performed successfully under close observation in two patients and changed to another operation in one patient. All patients were discharged uneventfully.

CONCLUSIONS

The incidence of intravenous misplacement of a nephrostomy tube following PCNL is 0.5% at our hospital. Intravenous nephrostomy tube misplacement is an uncommon complication of PCNL. A solitary kidney may render patients susceptible to this complication. Most patients may be managed conservatively with strict bed rest, intravenous antibiotics and one-step or two-step tube withdrawal under close monitoring.

Factors affecting complications according to the modified Clavien classification in complete supine percutaneous nephrolithotomy

INTRODUCTION

An increase in percutaneous nephrolithotomy (PCNL) has been accompanied by an increase in complications. We identified the parameters affecting the severity of complications using the modified Clavien classification (MCC).

METHODS

From 2008 to 2013, 330 patients underwent complete supine PCNL using subcostal access, one-shot dilation, rigid nephroscopy, and pneumatic lithotripsy. We assessed the impact of the following factors on complication severity based on the MCC: age, gender, body mass index, hypertension, diabetes, previous stone surgery and extracorporeal shock wave lithotripsy, preoperative hemoglobin, renal dysfunction (creatinine >1.4 mg/dL), preoperative urinary tract infection, anatomic upper urinary tract abnormality (AUUTA), significant (moderate-severe) hydronephrosis, stone-related parameters (opacity, number, burden, location, staghorn, complex stones), anesthesia type, kidney side, imaging and calyx for access, tract number, tubeless approach, operative time, postoperative hemoglobin, and hemoglobin drop and stone-free results.

RESULTS

The complication rate was 19.7% (MCC: 0=80.3%, I=6.4%, II=11.2%, ≥III=2.1%). On univariate analyses, only the following factors affected MCC: gender, preoperative hemoglobin, AUUTA, significant hydronephrosis, imaging for access, calyx for access, tract number, postoperative hemoglobin, hemoglobin drop and stone-free result. Renal dysfunction was accompanied by higher complications, yet the results were not statistically significant. Multivariate logistic regression analysis demonstrated renal dysfunction, absence of significant hydronephrosis, AUUTA, multiple tracts, lower postoperative hemoglobin, and higher postoperative hemoglobin drop as the significant parameters which affected MCC and predicted higher grades. The paper's limitations include a low number of cases in the higher Clavien grades and some subgroups of variables, and not applying some techniques due to surgeon preference.

INTERPRETATION

Many of the complete supine PCNL complications were in the lower Clavien grades and major complications were uncommon. Renal dysfunction, AUUTA, significant hydronephrosis, tract number, postoperative hemoglobin, and hemoglobin drop were the only factors affecting MCC.

Evaluation and comparison of urolithiasis scoring systems used in percutaneous kidney stone surgery

PURPOSE

Contemporary predictive tools for percutaneous nephrolithotomy outcomes include the Guy stone score, S.T.O.N.E. nephrolithometry and the CROES nephrolithometric nomogram. We compared each scoring system in the same cohort to determine which was most predictive of surgical outcomes.

METHODS

We retrospectively reviewed the records of patients who underwent percutaneous nephrolithotomy between 2009 and 2012 at a total of 3 academic institutions. We calculated the Guy stone score, the S.T.O.N.E. nephrolithometry score and the CROES nephrolithometric nomogram score based on preoperative computerized tomography images. A single observer at each institution reviewed all images and assigned scores. Univariate and multivariate analysis was done to determine the most predictive scoring system.

RESULTS

We enrolled 246 patients in study. In stone-free patients vs those with residual stones the mean Guy score was 2.2 vs 2.7, the mean S.T.O.N.E. score was 8.3 vs 9.5 and the mean CROES nomogram score was 222 vs 187 (each p <0.001). Logistic regression revealed that the Guy, S.T.O.N.E. nephrolithometry and CROES nomogram scores were significantly associated with stone-free status (p = 0.02, 0.004 and <0.001, respectively). The Guy and S.T.O.N.E. nephrolithometry scores were associated with estimated blood loss (p <0.0001 and 0.03) and length of stay (p = 0.03 and 0.009, respectively). The CROES nomogram did not predict estimated blood loss or length of stay.

CONCLUSIONS

All scoring systems and the stone burden equally predicted stone-free status. The Guy and S.T.O.N.E. nephrolithometry scores were associated with estimated blood loss and length of stay. A single scoring system should be adopted to unify reporting.

Analysis of the utility of stone gram stain in urolithiasis treated with percutaneous nephrolithotomy

OBJECTIVE

To define the sensitivity and specificity of stone gram stain for infected urolithiasis treated with percutaneous nephrolithotomy (PCNL).

METHODS

PCNL procedures performed at our institution were analyzed between January 2009 and May 2013. Stone fragments were sent in a sterile fashion for aerobic and fungal cultures. A gram stain and fungal smear were performed on the stones and reported within 24 hours of collection.

RESULTS

A total of 228 patients underwent 248 PCNLs. Of the 248 stones, 81 (33%) had a positive stone culture. Stone gram stain was positive in 31 cases and negative in 50. There were 167 negative stone cultures, and in these cases, gram stain was positive in 5 and negative in 162. The calculated sensitivity and specificity of stone gram stain were 38% and 97%. The positive and negative predictive values were 86% and 76%, respectively. In the subset of 16 patients with positive stone fungal cultures, fungal smear was performed in 12 and was positive in 4, giving fungal smear a sensitivity of 33%.

CONCLUSION

The results of this study suggest that stone gram stain cannot be relied on to detect a positive stone culture and may fail to detect up to 62% of infected stones. However, when positive, gram stain accurately predicts a positive stone culture in 86% of cases.

Current practices in percutaneous nephrolithotomy among endourologists

OBJECTIVE

To characterize current practices of percutaneous nephrolithotomy (PCNL) among endourologists in relation to practice setting, experience, and fellowship training.

METHODS

An Internet survey was administered to active Endourological Society members. Responses were grouped based on demographic information pertaining to setting of practice, number of years practiced, and fellowship training in endourology. PCNL technique details were evaluated and compared by each group. Statistical analysis was performed using SPSS.

RESULTS

Two hundred ninety-three completed responses of 2000 were received. There was a significant difference in the experience level among respondents (p < 0.001), with a relatively greater proportion being 11-20 years in practice. The majority of respondents were academic urologists (74%), with 18% being within a group-based private practice. Seventy-seven percent of respondents obtained their own access while 19% had access by interventional radiologists. Sixty-two percent were endourology fellowship trained, and fellows were significantly more likely to obtain their own access (82% vs 71%, p=0.022). Eighty-six percent used the prone position to obtain access, 10% used supine, and 4% used lateral decubitus. An antegrade approach was preferred by 68%, while 18.5% used a retrograde, and 12% used a combined approach. Overall, 76% placed a nephrostomy tube for postoperative drainage; a ureteral stent or catheter was placed in 28% or 11% of respondents, respectively, and only 6 respondents (2%) performed a "tubeless" procedure without any drainage.

CONCLUSIONS

The majority of Endourological Society members performing PCNLs who responded obtain their own access, and there is a higher proportion of self-obtained access in fellowship-trained endourologists. Prone positioning is predominant, and more than 75% of respondents leave a nephrostomy tube postoperatively, underscoring that the tubeless approach is rare.