Predictive factors of the outcome of extracorporeal shockwave lithotripsy for ureteral stones

The efficacy of early extracorporeal shockwave lithotripsy for the treatment of 5 to 10 mm upper ureteral stones: An observational study

This study aimed to determine the effectiveness of extracorporeal shockwave lithotripsy (SWL) performed in the early period (within the first 24 hours). Data of patients who underwent SWL with a diagnosis of unilateral radiopaque 5 to 10 mm upper ureteral stones were retrospectively examined. Patients were divided into 2 groups. Group 1 (early SWL) consisted of patients with SWL performed within 24 hours after the onset of colic pain (<24 hours), while group 2 (deferred SWL) comprised patients with SWL performed 24 hours or more from the onset of pain (≥24 hours). The primary endpoint of the study was planned to determine 1-month SFR in both groups. The secondary endpoint was determined to be the factor affecting SWL success. The mean age of 216 patients (130 men, 86 women) included in this study was 46.5 ± 12.1 years. SFR within 1 month was detected in 175 patients (81%). In the early SWL group, the average number of SWL sessions was fewer (1.26 vs 1.83 P = .026) and the time to the stone-free state was shorter (11 vs 15.4 days P = .044). SFR within 1 month was higher in the early SWL group (85.5% vs 71.8% P = .036). In multivariate analysis, stone size, Hounsfield Units, and early SWL were predictive factors for SWL success. Performing SWL within the first 24 hours is highly effective in patients with symptomatic 5 to 10 mm upper ureteral stones.

Extracorporeal shock wave lithotripsy: retrospective study on possible predictors of treatment success and revisiting the role of non-contrast-enhanced computer tomography in kidney and ureteral stone disease

Extracorporeal shock wave lithotripsy (ESWL) is a safe and efficient treatment option for urinary stone disease. The overall stone-free rate (SFR) varies significantly. This study aimed to assess the influence of stone size, location, stone density, and skin-to-stone distance (SSD), on the outcome of ESWL. We assessed whether pre-treatment non-contrast-enhanced CT scan (NCCT) confers significant advantages compared to kidney-ureter-bladder film (KUB) only. We reviewed the medical records of 307 cases (165 men, 142 women) with renal and ureteral stones treated consecutively at our institution with ESWL between 2020 and 2023. 44 of these underwent a NCCT. The outcome of ESWL was defined in two ways: visible stone fragmentation on KUB, and the need for further treatment. Overall success of fragmentation was 85% (261 patients). 61% of patients (n = 184) didn't need any further treatment. Stone size and location correlated significantly with treatment outcomes regarding the need for further treatment (p = 0.004) and stone fragmentation (p = 0.016), respectively. Unlike mean SSD (p = 0.462), the mean attenuation value (MAV) significantly correlated with the need for retreatment (p = 0.016). MAV seems to be a better predictor of treatment success (AUC of the ROC curve: 0.729), compared to stone size (AUC: 0.613). The difference between groups (with and without NCCT) in both treatment outcomes did not reach statistical significance. During decision-making, information regarding SSD and MAV can be useful in more dubious scenarios. However, it appears that their inclusion doesn't provide substantial advantages when compared to relying solely on KUB.

Efficacy and Safety of Extracorporeal Shock Wave Lithotripsy (ESWL) in Patients With Infected Ureterohydronephrosis Due to Ureteral Stones Following Double-J Catheter Insertion

INTRODUCTION

Double-J ureteral catheters in patients with ureteral lithiasis undergoing extracorporeal shockwave lithotripsy (ESWL) procedures reduce the efficacy of the procedure or have no effect on the stone-free rate. However, the effect of double-J catheters on the patients in whom they were inserted for infected hydronephrosis is not known. The aim of our study was to evaluate the efficacy and safety of the ESWL procedure in patients with ureteral lithiasis and double-J catheters previously inserted for infected hydronephrosis.

METHOD

We conducted a comparative case-control, match-paired study in a group of patients with ureteral lithiasis treated by ESWL from January 1, 2018, to March 1, 2023, who were divided into two groups according to the presence of the double-J catheter. For each patient with the double-J catheter from the study group, we selected one patient for the control group without the double-J catheter and matched them in terms of size, location of stones, and body mass index (BMI). We analyzed the stone-free rate and complications that occurred in the two groups.

RESULTS

Forty patients with ureteral lithiasis and a double-J catheter inserted for infected hydronephrosis were enrolled in the study group. The control group included 40 patients with ureteral stones without double-J catheters. The patients in the two groups were predominantly men with stones located in the lumbar region and on the right side and with a BMI between 25 and 30 kg/m2. The stones had an average size of 0.9+/-0.12mm and 0.89+/-0.15mm, respectively (p=0.624). There was no statistically significant difference in stone-free rate between the two groups after the first session of ESWL (47.5% vs. 52.5%, p=0.502), the second (70% vs. 75%, p = 0.616), and the third session (85% vs. 87.5%, p=0.761). The rate of complications was similar in both groups (7.5% vs. 5%, p=0.761).

CONCLUSIONS

The presence of double-J catheters inserted in patients with ureteral stones who underwent ESWL for infected hydronephrosis does not affect the stone-free rate of the procedure or the complication rate. The procedure of ESWL in patients with ureteral lithiasis and double-J catheters inserted for infected hydronephrosis is a safe and efficient method that can be recommended as an initial treatment alongside retrograde ureteroscopy.

A Prospective Study on the Impact of Clinical Factors and Adjusted Triple D System for Success Rate of ESWL

Objective: Our study aimed to evaluate the success rate of ESWL and identify relevant treatment-specific factors affecting treatment outcomes, as well as to assess the accuracy of the updated Triple D scoring system and compare it with older systems. Material and Methods: A prospective study of 71 patients who received ESWL treatment for renal stones that were 5-15 mm in size was completed. The patient having no residual stones or residual stones lesser than 4 mm after ESWL was identified as a treatment success. Univariate and multivariate logistic regression and ROC curves were used to identify important factors for treatment outcomes. Results: Successful treatment was achieved for 66.2% of patients. The stone volume (SV), mean stone density (MD), and delivered power to the stone volume unit ratio (SMLI/SV) were defined as the most critical factors influencing ESWL success. An updated Triple D score system with a, SMLI/SV ratio could be an alternative to older systems and reach an even higher accuracy. A limitation of this study is the limited sample size due to the COVID-19 pandemic. Conclusions: Our results show that the three factors that most influence the success of ESWL are the stone size, mean stone density, and SMLI/SV ratio. Based on this, we present a simple updated triple D score system to predict ESWL success, which could be implemented in future clinical practice.

Finding the optimal candidate for shock wave lithotripsy: external validation and comparison of five prediction models

We aimed to externally validate five previously published predictive models (Ng score, Triple D score, S3HoCKwave score, Kim nomogram, Niwa nomogram) for shock wave lithotripsy (SWL) single-session outcomes in patients with a solitary stone in the upper ureter. The validation cohort included patients treated with SWL from September 2011 to December 2019 at our institution. Patient-related variables were retrospectively collected from the hospital records. Stone-related data including all measurements were retrieved from computed tomography prior to SWL. We estimated discrimination using area under the curve (AUC), calibration, and clinical net benefit based on decision curve analysis (DCA). A total of 384 patients with proximal ureter stones treated with SWL were included in the analysis. Median age was 55.5 years, and 282 (73%) of the sample were men. Median stone length was 8.0 mm. All models significantly predicted the SWL outcomes after one session. S3HoCKwave score, Niwa, and Kim nomograms had the highest accuracy in predicting outcomes, with AUC 0.716, 0.714 and 0.701, respectively. These three models outperformed both the Ng (AUC: 0.670) and Triple D (AUC: 0.667) scoring systems, approaching statistical significance (P = 0.05). Of all the models, the Niwa nomogram showed the strongest calibration and highest net benefit in DCA. To conclude, the models showed small differences in predictive power. The Niwa nomogram, however, demonstrated acceptable discrimination, the most accurate calibration, and the highest net benefit whilst having relatively simple design. Therefore, it could be useful for counselling patients with a solitary stone in the upper ureter.

Non-contrast computed tomography-based factors in predicting ESWL success: A systematic review and meta-analysis

PURPOSE

We assessed the efficacy of some predictive factors that can be measured with non-contrast computed tomography and may affect ESWL success with a systematic review and meta-analysis.

MATERIALS AND METHODS

All data sources were broadly investigated up to April 2022. Data were extracted from the relevant studies and analyzed with RevMan software. In a random effects model, standard mean difference (SMD) and risk ratio (RR) values were given with 95% confidence intervals.

RESULTS

In total, pooled analysis included 7148 patients in 43 studies. The combined effect estimate showed significant differences between the ESWL success and ESWL failure groups in terms of Hounsfield unit (HU), Hounsfield density (HD), skin to stone distance (SSD), ureteral wall thickness (UWT), stone volume, stone area, abdominal fat parameters, diameter of proximal ureter, and hydronephrosis. However, perinephric stranding and renal cortical thickness were not found to be statistically significant between the study groups.

CONCLUSIONS

HU, HD, SSD, UWT, stone volume, stone area, abdominal fat parameters, diameter of proximal ureter and hydronephrosis are effective factors for prediction of ESWL success. It is important to decide on treatment before the procedure for stones with appropriate diameter for ESWL.

A Comparative Study of Stone Re-Treatment after Lithotripsy

The high recurrence rate has always been a problem associated with urolithiasis. This study aimed to explore the effectiveness of single interventions, combined therapies, and surgical and nonsurgical interventions. Herein, three lithotripsy procedures—extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), and ureteroscopic lithotripsy (URSL)—were assessed and a retrospective cohort was selected in order to further analyze the association with several risk factors. Firstly, a population-based cohort from the Taiwan National Health Insurance Research Database (NHIRD) from 1997 to 2010 was selected. In this study, 350 lithotripsy patients who underwent re-treatment were followed up for at least six years to compare re-treatment rates, with 1400 patients without any lithotripsy treatment being used as the comparison cohort. A Cox proportional hazards regression model was applied. Our results indicate that the risk of repeat urolithiasis treatment was 1.71-fold higher in patients that received lithotripsy when compared to patients that were not treated with lithotripsy (hazard ratio (HR) 1.71; 95% confidence interval (CI) = 1.427−2.048; p < 0.001). Furthermore, a high percentage of repeated treatment was observed in the ESWL group (HR 1.60; 95% CI = 1.292−1.978; p < 0.001). Similarly, the PCNL group was also independently associated with a high chance of repeated treatment (HR 2.32; 95% CI = 1.616−3.329; p < 0.001). Furthermore, age, season, level of care, and Charlson comorbidities index (CCI) should always be taken into consideration as effect factors that are highly correlated with repeated treatment rates.

The effect of stone and patient characteristics in predicting extra-corporal shock wave lithotripsy success rate: A cross sectional study

Introduction

We determine the effect of patient characteristics (age, sex, and body mass index BMI) and stone characteristics (density, location, and size) by non-contrast computed tomography of the kidneys, ureters, and bladder (CT-KUB) in predicting the success of extracorporeal shock wave lithotripsy (ESWL) in the treatment of kidney and ureteric stones. We present this study to further enrich the knowledge of physicians towards the effect of different patient characteristics upon predicting extra-corporal shock wave lithotripsy success rates.

Methods

We evaluated 155 patients who received ESWL for renal and ureteric stone measuring 3–20 mm (mm), over a 3-month period. The stone size in millimeters, density in Hounsfield units (HU) and its location was determined on pre-treatment CT-KUB. ESWL was successful if post-treatment residual renal stone fragments were ≤3 mm and for ureteric stones should be totally cleared.

Results

The overall success of ESWL treatment was observed in 65.8% of the 155 patients. There was no significant difference seen when the effect of patients age, sex and BMI were studied with ESWL outcome with P values were 0.155, 0.101 and 0.415 respectively. Also, stone location either in the kidney or ureter has no statistically significant effect on ESWL response rate. while stone density and size determined on CT KUB have statistically significant effect on the success rate of ESWL with a P-value of 0.002 and 0.000 respectively.

Conclusions

This study shows that determination of stone density and stone size on CT KUB pre ESWL can help to predict the outcome of ESWL. We propose that stone density <500 HU and stone size < 5 mm are highly likely to result in successful ESWL.

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Previous studies have reported a wide variation of ESWL success rate ranging from 46% to 91%.

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Failure of ESWL results in unnecessary exposure of renal parenchyma to shock waves and complications like renal hematoma.

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Increasing Efforts have been made to determine factors that predict ESWL outcome and improve patients' selection.

Can we successfully predict the outcome for extracorporeal shock wave lithotripsy (ESWL) for medium size renal stones? A single-center experience

BACKGROUND

Extracorporeal shock wave lithotripsy (ESWL) is one of the most used modalities in treatment of renal stones, but its effectiveness can be influenced by many factors related to the patient or the stone itself which may affect the success of stone disintegration. The aim of our study was to investigate the predictive value of some patient and stone-related factors for ESWL success for renal stones.

METHODS

A total of 100 patients with single radiopaque renal stone 10-20 mm in diameter, undergoing ESWL were enrolled in this study. All patients had non contrast computed tomography (NCCT) done before ESWL. We evaluated body mass index (BMI), skin-to-stone distance (SSD), stone size and Hounsfield density comparing these values between stone free (SF) and residual stone (RS) groups.

RESULTS

Of the 100 patients, 70% had successful disintegration. There was no significant difference between stone free (SF) and residual stone (RS) groups as regard age or BMI. Meanwhile, there was a significant difference between SF and RS groups as regard stones' density and SSD, with higher values in RS group but there was statistically insignificant difference as regard stone size (p = 0.522). Using logistic regression analysis, we found that Hounsfield unit (HU) was better in predicting successful disintegration than SSD but without statistical significance.

CONCLUSION

HU and SSD are the independent predictive factors for ESWL outcome, and they should be considered when planning ESWL in treatment of medium size renal stones.

Outcomes of extracorporeal shock wave lithotripsy for ureteral stones according to ESWL intensity

Background

We evaluated the treatment outcomes of ureteral stones according to energy intensity generated by extracorporeal shock wave lithotripsy (ESWL).

Methods

We retrospectively analyzed 150 patients who underwent ESWL for treatment of ureteral stones between September 2018 and February 2020. All stones were confirmed by a computed tomography examination, and the size, location, skin-to-stone distance, and Hounsfield units (HU) of the stones were assessed. In addition, patient characteristics including body mass index and estimated glomerular filtration rate, which can affect treatment outcome, were also evaluated. The success or failure of ESWL was confirmed according to the session, and the factors affecting the treatment outcome were analyzed using a logistic regression model.

Results

Of the 150 patients, 82 (54.7%) had stones in the proximal ureter, 5 (3.3%) in the mid, and 63 (42.0%) in the distal ureter. Patients underwent ESWL an average of 1.5 times, and the success rate according to session was 65.3% for the first, 83.3% for the second, and 90.0% for the third session. A multivariate analysis revealed that stone size [odds ratio (OR) 0.81, 95% confidence interval (CI), 0.66–0.99, P=0.049] and HU (OR 0.99, 95% CI, 0.98–0.99, P=0.001) were significant factors affecting the success rate after the first ESWL session; ESWL intensity was not related to success rate. Stone size (OR 0.78, 95% CI, 0.62–0.96, P=0.022) was the only significant factor affecting the success rate in the third session.

Conclusions

Stone size and HU affected the ESWL success rate. ESWL intensity was not significantly related to the success rate, so it should be adjusted according to patient pain and the degree of stone fragmentation.

Role of Stone Heterogeneity Index in Determining Success of Shock Wave Lithotripsy in Urinary Calculi

INTRODUCTION

Various stone factors can affect the outcome of shock wave lithotripsy (SWL). A novel factor called the stone heterogeneity index (SHI) may have an impact on stone free rates. The objective of this study was to assess the role of SHI in SWL outcomes.

METHODS

Patients' medical records were reviewed for the collection of data variables. They were subjected to SWL, using an electromagnetic lithotripter machine (Storz Modulith SLX-MX). Computation of mean stone density (mean value of the Hounsfield units) and SHI was accomplished by generating elliptical regions of interest on the computed tomography (CT) scan images. Grouping was performed on the basis of stone free and failure outcomes. Relevant statistical tests were applied for continuous and categorical variables. P ≤ 0.05 was considered statistically significant.

RESULTS

Overall, 385 subjects were included having a mean age of 38.4 ± 14.7 years. The cohort comprised 276 (71.7%) males and 109 (28.3%) female patients. A total of 234 (60.8%) patients were rendered successful (stone free after one session) while 151 (39.2%) of the patients were declared to have failed the SWL procedure. Stone length, stone density, and SHI values were 13.7 ± 7.6 mm, 935 ± 404, and 201 ± 107, respectively. The stone density, SHI, and stone length were significantly different between the two groups (p-values of 0.001, 0.02, and 0.04, respectively).

CONCLUSIONS

SHI can be a helpful CT scan-based parameter to assess stone fragility. It can help clinicians in the judicious selection of patients before implementing SWL procedure.

RELEVANCE FOR PATIENTS

Non-contrast CT-based stone parameters have been found to be effective for predictions of outcomes. SHI can be a helping tool to better predict SWL success rates when treating the renal stones.

Prognostic impact of perirenal fat stranding on oncologic outcomes in ureteral urothelial carcinoma

PURPOSE

Perirenal fat stranding (PRFS) is defined as linear areas of soft-tissue attenuation in the perirenal space that can result from ureteral obstruction. We analyzed the prognostic impact of PRFS on outcomes in patients with ureteral urothelial carcinoma (UC).

MATERIALS AND METHODS

Overall, 126 patients evaluated preoperatively by computerized tomography (CT) scan and diagnosed with ureteral UC following nephroureterectomy between January 2001 and May 2018 were included. We analyzed associations between oncologic outcomes and secondary signs such as hydronephrosis and PRFS.

RESULTS

Overall, 68 patients (54.0%) showed PRFS on preoperative CT scans. The patients' mean age was 66.33±9.49 years. A high pT stage (≥T3) was seen in 47 patients (37.3%) and high-grade tumors were seen in 90 patients (71.4%). Lymphovascular invasion (LVI) was seen in 15 patients (11.9%), and 5 (4.0%) were at the pN1 stage. Multivariate Cox analysis showed that cT stage≥3, PRFS, pT stage≥3, tumor grade, LVI, and pN1 stage were independent prognostic factors of recurrence-free survival (RFS) and cancer-specific survival (CSS) (all p<0.05).

CONCLUSIONS

PRFS was found to be an independent prognostic factor for RFS and CSS. PRFS is easily detectable in preoperative CT imaging and may be useful for improving the prediction of oncologic outcomes of ureteral UC. Therefore, PRFS along with other important preoperative CT findings can help urologists give preoperative advice to patients with ureteral UC before surgical management.

Surgical management of urinary stone

Urolithiasis is a common urological disease that causes a significant deterioration in patients’ life quality due to severe pain and frequent recurrence. With increases in the incidence of urolithiasis, different treatment methods have been developed. Although urolithiasis is still managed in Korea with extracorporeal shock wave lithotripsy, the development of minimally invasive techniques and endoscopy instruments has led to increased surgery. Prior to the introduction of endoscopy, urolithiasis surgery was performed as open procedures such as ureterolithotomy, pyelolithotomy, and nephrolithotomy. However, most recent stone surgeries are performed using endoscopy with comparable outcomes and fewer complications. Laparoscopic or robot-assisted laparoscopic surgeries are performed in exceptional cases. Since urolithiasis can be found in various urinary organs, such as the kidney, ureter, bladder, and even the urethra, the approach, method, and availability of endoscopy will vary depending on the stoneʼs size and location. Understanding the types and characteristics of each surgical method will determine the appropriate procedure for each patient and improve the surgical outcomes.

Secondary signs on preoperative CT as predictive factors for febrile urinary tract infection after ureteroscopic lithotripsy

Background

Febrile urinary tract infection (UTI) is one of the most common complications after ureteroscopic lithotripsy (URS). We evaluated the effect of secondary signs on preoperative computed tomography (CT) for febrile UTI after URS.

Methods

In total, 182 patients who underwent URS for ureteral stones from January 2013 to December 2015 were retrospectively included in this study. These patients were divided into two groups according to the presence of postoperative febrile UTI after URS. We compared the clinical factors, stone factors, and secondary signs between the groups. Predictive factors for febrile UTI after URS were analyzed using a multivariate logistic regression model.

Results

Febrile UTI occurred in 26 of the 182 patients. In univariate analysis, presence of comorbid chronic kidney disease (CKD) and stone size were significantly different between UTI and non-UTI groups. Among secondary signs, presence of hydroureter, perinephric fat stranding, periureteral fat stranding, and tissue rim sign were significantly different between the groups. In multivariate logistic regression analysis, comorbid CKD, stone size, perinephric fat stranding, and tissue rim sign were independent predictive factors for febrile UTI after URS.

Conclusion

This study demonstrated that secondary signs including perinephric fat stranding and tissue rim sign on preoperative CT, CKD, and stone size are independent predictive factors for febrile UTI after URS.

Machine learning prediction of stone-free success in patients with urinary stone after treatment of shock wave lithotripsy

BACKGROUND

The aims of this study were to determine the predictive value of decision support analysis for the shock wave lithotripsy (SWL) success rate and to analyze the data obtained from patients who underwent SWL to assess the factors influencing the outcome by using machine learning methods.

METHODS

We retrospectively reviewed the medical records of 358 patients who underwent SWL for urinary stone (kidney and upper-ureter stone) between 2015 and 2018 and evaluated the possible prognostic features, including patient population characteristics, urinary stone characteristics on a non-contrast, computed tomographic image. We performed 80% training set and 20% test set for the predictions of success and mainly used decision tree-based machine learning algorithms, such as random forest (RF), extreme gradient boosting trees (XGBoost), and light gradient boosting method (LightGBM).

RESULTS

In machine learning analysis, the prediction accuracies for stone-free were 86.0, 87.5, and 87.9%, and those for one-session success were 78.0, 77.4, and 77.0% using RF, XGBoost, and LightGBM, respectively. In predictions for stone-free, LightGBM yielded the best accuracy and RF yielded the best one in those for one-session success among those methods. The sensitivity and specificity values for machine learning analytics are (0.74 to 0.78 and 0.92 to 0.93) for stone-free and (0.79 to 0.81 and 0.74 to 0.75) for one-session success, respectively. The area under curve (AUC) values for machine learning analytics are (0.84 to 0.85) for stone-free and (0.77 to 0.78) for one-session success and their 95% confidence intervals (CIs) are (0.730 to 0.933) and (0.673 to 0.866) in average of methods, respectively.

CONCLUSIONS

We applied a selected machine learning analysis to predict the result after treatment of SWL for urinary stone. About 88% accurate machine learning based predictive model was evaluated. The importance of machine learning algorithm can give matched insights to domain knowledge on effective and influential factors for SWL success outcomes.

Factors predictive of shockwave lithotripsy failure for ureteral stones: why we need to hurry

BACKGROUND

The aims of this study are to evaluate the prognostic factors of extracorporeal shockwave lithotripsy in patients with ureteric stones, and to identify which patients might directly benefit of an endoscopic treatment.

METHODS

We performed a prospective study from January 2013 and July 2016 on patients with single ureteric stone and undergoing extracorporeal shockwave lithotripsy (SWL). We divided patients into two groups: first group (success group) included cases resolved with SWL only, and a second group (failure group) including patients with stone not resolved by SWL and requiring an endoscopic treatment. We evaluated age, weight, height, body mass index, stone size, hydronephrosis, laterality, location, days elapsed from onset of symptoms to SWL and stone density when computed tomography was performed. In case of stone fragments >4 mm, the procedure was repeated up to a maximum of three times. SWL was considered as failed if patients had a residual stone of any size after a follow-up of 3 months or if a complication occurred.

RESULTS

274 patients completed follow-up and were enrolled in the study. Mean age was 53.22 years (standard deviation: 13.98). SWL overall success rate was 84.3% (231 patients successfully treated with shockwaves) and failure rate was 15.7% (43 patients underwent auxiliary endoscopic procedure). At the univariate analysis, we observed a statistically significant difference for hydronephrosis (P=0.006), time elapsed from symptoms onset (P=0.013), patients' age (P=0.06) and mean stone density (0.023). In the multivariate logistic regression, patients' age (OR: 1.517), and time elapsed from obstruction to SWL (OR: 3.005) were independent predictive factors for SWL failure. Furthermore, moderate and severe hydronephrosis seemed to be independent predictive factors for SWL failure, presenting an OR of 2.451 and 4.207 respectively. High stone density resulted to be a predictive factor for SWL failure (OR: 2.293 if density was higher than 1100 Hounsfield Units).

CONCLUSIONS

We report a large series of patients undergone primary SWL for ureteric stones. Our data demonstrated the role of hydronephrosis, time elapsed from obstruction onset to treatment and stone density as independent predictive factors of SWL failure.

The Influence of Pain on the Outcome of Extracorporeal Shockwave Lithotripsy

Introduction

The aim of this study was to determine the predictive value of pain scores on the efficacy of extracor-poreal shockwave lithotripsy (ESWL) and to identify other predictive risk factors for treatment success.

Materials and Methods

A total of 476 patients who underwent ESWL (piezoelectric lithotripsy) for urolithiasis between September 2011 and December 2015 were identified. The primary end-point of this study was success rate, which was evaluated 4 months after ESWL. The secondary outcome was the occurrence of complications as a result of ESWL.

Results

The average pain perception was reported at 5 on a scale from 0 to 10. The overall success rate of ESWL was found to be 43.9% and the success rate after the first ESWL was 35.1%. Univari-ate analysis showed no significant correlation between pain score and success of ESWL (p = 0.135). The level of intensity was correlated with pain scores (Pearson correlation -0.423, p < 0.001). Univariate analysis identified five predictive factors: sex, stone location, stone size, hydronephrosis and the use of tamsulosin. Multivariate logistic regression analysis showed that sex, stone location and size independently in-fluenced the success of ESWL (p = 0.045, p = 0.001 and p < 0.001).

Conclusion

No correlation was found between the pain scores and efficacy of ESWL. Despite this absence, pain scores during ESWL sessions remain high and additional analgesia would improve patient satisfaction.

Noncontrast Computed Tomography Parameters for Predicting Shock Wave Lithotripsy Outcome in Upper Urinary Tract Stone Cases

Kidney stones are a major public health concern with continuously increasing worldwide prevalence. Shock wave lithotripsy (SWL) is the first line treatment choice for upper urinary tract calculi with ureteroscopy and has advantages of safety and noninvasiveness, but the treatment success rate of SWL is lower than that of other therapies. It is therefore important to identify predictive factors for SWL outcome and select a suitable treatment choice for patients with upper urinary tract calculi. In recent years, computed tomography (CT) has become the gold standard for diagnosis of upper urinary tract calculi. Several factors based on CT images, including skin-to-stone distance, mean stone density, stone heterogeneity index, and variation coefficient of stone density, have been reported to be useful for predicting SWL outcome. In addition, a new method of analysis, CT texture analysis, is reportedly useful for predicting SWL outcomes. This review aims to summarize CT parameters for predicting the outcome of shock wave lithotripsy in stone cases in the upper urinary tract.

Noncontrast computed tomography factors predictive of extracorporeal shock wave lithotripsy outcomes in patients with pancreatic duct stones

Purpose

To assess the usefulness of factors unique to NCCT for the prediction of ESWL outcomes in patients with pancreatic duct stones.

Materials and methods

We retrospectively evaluated 148 patients with multiple PDS who had undergone ESWL therapy. All patients received an examination for NCCT both before and after ESWL. The following parameters were measured and recorded: patient characteristics including sex and age; NCCT parameters including mean stone length, mean stone volumes before and after ESWL, mean value of CT attenuation, standard deviation of CT attenuation, variation coefficient of CT attenuation, skin-to-stone distance, and pancreatic duct diameter; ESWL outcome indexes including stone clearance rate calculated using the formula \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{V0 - V1}{V0} \times 100\%$$\end{document}V0-V1V0×100%, and the number of ESWL sessions. All patients were divided into groups based on their SCR: A group (SCR ≥ 90%), B group (SCR between 50% and 90%), and C group (SCR < 50%). Analysis of variance was used among the three groups to evaluate the potential predictors of SCR, and a receiver-operating curve was established to determine the optimal cutoff value.

Results

ANOVA analysis revealed that MSD was the only significant predictor for SCR (p < 0.05), and ROC indicated an optimal cutoff value of +1000.45 HU, with a sensitivity up to 78.0% and specificity of 48.6%. Stones with MSD lower than +1000.45 HU had higher SCR (69.3%) than that of higher-density ones (59.6%). Pearson correlation analysis and histogram indicated a significant positive correlation between ESWL No. and MSL (r = 0.536), MSD (r = 0.250), SDSD (r = 0.247), and PDD (r = 0.227), all values being p < 0.01.

Conclusion

MSD is the optimal predictor of ESWL efficacy, and PDS with lower MSD had a better clearance rate with fewer fragmentation sessions.

Factors Affecting the Outcome of Extracorporeal Shockwave Lithotripsy in Urinary Stone Treatment

Objectives

We sought to evaluate the factors affecting the outcome of extracorporeal shockwave lithotripsy (ESWL) in urinary stone treatment.

Methods

We conducted a retrospective review of 235 adult patients treated with ESWL, for radiopaque renal or ureteric stones between January 2015 and December 2016. Patient's age, sex, stone size, laterality, location, density, skin-to-stone distance (SSD), and presence of double J stent were studied as potential predictors. At the end of three months, the patients were divided into success and failure groups and the significance was determined.

Results

Of the 235 patients (188 males and 47 females) analyzed, ESWL was successful in 79.1%. Univariate analysis of both groups revealed no significant difference in patient's age and stone laterality. Statistically significant differences in gender, stone size, stone site, stone density, SSD, and patients with stents were observed. Statistically significant factors in multivariate logistic regression analysis were sex and stent. Females had three-times higher risk for ESWL failure than males (odds ratio (OR) = 3.213; 95% confidence interval (CI): 1.194-8.645; p = 0.021) and a higher failure rate when a stent was used (OR = 6.358; 95% CI: 2.228-18.143; p = 0.001).

Conclusions

This study revealed that ESWL can treat renal and ureteric stones successfully with an inverse association between outcome and predictors such as stone size and density, SSD, and stent presence. These factors can help us in improving patient selection and ensure better results at lower cost.

Predictive factors and treatment outcomes of Steinstrasse following shock wave lithotripsy for ureteral calculi: A Bayesian regression model analysis

Purpose

This study aims to assess the predictive factors and treatment outcomes of Steinstrasse formation following shock wave lithotripsy (SWL) for ureter stone.

Materials and Methods

The medical records of 1,418 ureter stone patients who underwent one-session SWL from November 2005 to May 2013 at our medical institute were retrospectively reviewed. Finally, 551 patients met inclusion criteria. Maximal length and location of stone, stone attenuation (Hounsfield units), and skin-to-stone distance (SSD) were determined on pretreatment non-contrast computed tomography.

Results

Of 551 patients, 12 patients (2.2% of total cohort) developed Steinstrasse after one-session SWL. The Steinstrasse incidence was significantly associated with stone size, stone attenuation value, and SSD. Prophylactic ureter stenting was not a statistically significant predictor of Steinstrasse formation. After propensity-score matching, Steinstrasse group showed a significant shorter SSD compare to non-Steinstrasse group. Multivariate logistic regression and Bayesian analysis revealed that stone size, stone attenuation and SSD were significant predictor of Steinstrasse formation following SWL for ureter stone. The Steinstrasse resolved spontaneously in six patients and remaining six patients were treated by additional SWL. None of patients with Steinstrasse required ureteral stenting, percutaneous drainage, or consequent surgical intervention.

Conclusions

Steinstrasse formation following SWL for ureter stone was rare event but nonnegligible. Large stone size, high stone attenuation and short SSD were significant predictors of Steinstrasse formation following SWL for ureter stone. Majority of patients with Steinstrasse formation could be treated conservatively in this clinical scenario.

Role of clinical and radiological parameters in predicting the outcome of shockwave lithotripsy for ureteric stones

Introduction:

Shockwave-lithotripsy (SWL) provides a noninvasive and effective option for the management of ureteric calculi. Several factors may affect the success of SWL. Identification of these predictive factors will both increase the efficacy and decrease the cost. This study was designed to identify factors affecting the outcome of SWL for ureteral stones.

Materials and Methods:

This study was conducted from March 2012 to November 2014 in patients with solitary ureteric calculi who were managed with SWL. Data were analyzed to identify clinical and radiological factors associated with treatment outcome. Success after SWL was described as complete stone clearance or clinically insignificant residual fragments <3 mm at 3 months after SWL.

Results:

A total of 110 patients with ureteric calculi were divided into two groups depending on the outcome of SWL, Group A (successful - 76%) and Group B (failed - 24%). Stone size, Skin to stone distance (SSD), secondary signs of obstruction, and presence of double J (DJ) Stent, all were significantly associated with the outcome of SWL on univariate analysis. On multivariate analysis, stone size, hounsfield unit, SSD, and DJ stent were the independent factors affecting the outcome of SWL. On Receptor-Operator Characteristic curve analysis, a cutoff value of 8.2 mm for the stone size was found which best predicts a successful outcome, with a sensitivity of 54% and specificity of 96%.

Conclusion:

The findings of this study suggest that Stone size, SSD, the presence of DJ stent, and stone attenuation values are the significant factors that influence the outcome of SWL in patients with ureteral stones.

Non-Contrast Computed Tomography Scan Based Parameters of Ureteric Stones Affecting the Outcome of Extracorporeal Shock Wave Lithotripsy

Objective 

To compare the non-contrast computed tomography (NCCT) scan-based parameters of ureteric stones affecting the outcome of extracorporeal shock wave lithotripsy (ESWL).

Materials and methods

We retrospectively evaluated the pre-procedure NCCT of 74 patients who had ESWL for solitary ureteric calculi of 5-20 mm in diameter. We assessed the age, sex, basal metabolic index (BMI), laterality, location, presence of double 'J' (DJ) stent, skin to stone distance (SSD), stone maximum diameter, Hounsfield unit (HU), Hounsfield density (HD), area, and volume. All those who had no stone on follow-up imaging within 30 days were declared successful while those who had residual stone were declared failures.

Results

The overall success rate was 78% (58/74). Sixty (81.1%) patients were male. The success of ESWL was correlated with lower SSD, Hounsfield units (HU) and Hounsfield density (HD). However, in multivariate analysis, SSD, Hounsfield unit, and stone area showed correlation with success of procedure but Hounsfield density failed to show correlation. The success rate in patients with stone HU <500, 500-1000 and >1000 were 93.9%, 69%, and 58.3%, respectively. Patients with lower BMI (<30 kg/m²) and HD (<76 HU/mm) were more prone towards success of the procedure than those with higher BMI (>30 kg/m²) and higher HD (>76 HU/mm).

Conclusion

BMI, SSD, stone Hounsfield units and Hounsfield unit density were strong predictors of outcome of ESWL for ureteric stone.

Comparison of Extracorporeal Shock Wave Lithotripsy for Urolithiasis Between Children and Adults: A Single Centre Study

Objective

To retrospectively evaluate the effectiveness of extracorporeal shock wave lithotripsy (ESWL) for urolithiasis and compare the results between children and adults.

Materials and methods

From January 2011 to January 2015 (four years), ESWL was performed in 104 children and 300 adults for urolithiasis. MODULITH^® SLX-F2 lithotripter (Storz Medical AG, Tägerwilen, Switzerland) equipment was used for ESWL. The stone-free rates, the number of ESWL sessions required, complication rates and ancillary procedures used were evaluated in a comparative manner.

Results

The mean age ± standard deviation (SD) of children was 7.84±4.22 years and of adults was a 40.22±1.57 years. Mean ± SD of the stone size was 1.28±61 cm in the adults while 1.08 ± 0.59 cm in the children. In adults, the complications included steinstrasse in six (1.98%) patients, fever in 15 (4.95%), hematuria in 19 (6.28%) and sepsis in six (1.98%) patients. In children, steinstrasse was observed in two (1.9%), mild fever in two (1.9%), hematuria in six (5.7%) and sepsis was seen in four (3.8%) patients. The overall complication rate in the adults and in the children, it was found to be 46/300 (15%) and in the children, it was seen to be 14/104 (13%). No statistical difference was found in post-ESWL complications between children and adults (P>0.05). Ancillary procedures including double J (DJ) stent were used in 13 (12.5%) children and 87 (29%) adults. There was a better stone clearance rate in children i.e. 79% as compared to 68% in adults (X²: P=0.036).

Conclusion

Children can achieve high stone-free rates after ESWL with a lower need for repeat ancillary procedures as compared to adults. However, there is a difference in the post-ESWL complications between these groups.

Is scoring system of computed tomography based metric parameters can accurately predicts shock wave lithotripsy stone-free rates and aid in the development of treatment strategies?

Objective:

The objective was to determine the predicting success of shock wave lithotripsy (SWL) using a combination of computed tomography based metric parameters to improve the treatment plan.

Patients and Methods:

Consecutive 180 patients with symptomatic upper urinary tract calculi 20 mm or less were enrolled in our study underwent extracorporeal SWL were divided into two main groups, according to the stone size, Group A (92 patients with stone ≤10 mm) and Group B (88 patients with stone >10 mm). Both groups were evaluated, according to the skin to stone distance (SSD) and Hounsfield units (≤500, 500–1000 and >1000 HU).

Results:

Both groups were comparable in baseline data and stone characteristics. About 92.3% of Group A rendered stone-free, whereas 77.2% were stone-free in Group B (P = 0.001). Furthermore, in both group SWL success rates was a significantly higher for stones with lower attenuation <830 HU than with stones >830 HU (P < 0.034). SSD were statistically differences in SWL outcome (P < 0.02). Simultaneous consideration of three parameters stone size, stone attenuation value, and SSD; we found that stone-free rate (SFR) was 100% for stone attenuation value <830 HU for stone <10 mm or >10 mm but total number SWL sessions and shock waves required for the larger stone group were higher than in the smaller group (P < 0.01). Furthermore, SFR was 83.3% and 37.5% for stone <10 mm, mean HU >830, SSD 90 mm and SSD >120 mm, respectively. On the other hand, SFR was 52.6% and 28.57% for stone >10 mm, mean HU >830, SSD <90 mm and SSD >120 mm, respectively.

Conclusion:

Stone size, stone density (HU), and SSD is simple to calculate and can be reported by radiologists to applying combined score help to augment predictive power of SWL, reduce cost, and improving of treatment strategies.

Stone heterogeneity index as the standard deviation of Hounsfield units: A novel predictor for shock-wave lithotripsy outcomes in ureter calculi

We investigated whether stone heterogeneity index (SHI), which a proxy of such variations, was defined as the standard deviation of a Hounsfield unit (HU) on non-contrast computed tomography (NCCT), can be a novel predictor for shock-wave lithotripsy (SWL) outcomes in patients with ureteral stones. Medical records were obtained from the consecutive database of 1,519 patients who underwent the first session of SWL for urinary stones between 2005 and 2013. Ultimately, 604 patients with radiopaque ureteral stones were eligible for this study. Stone related variables including stone size, mean stone density (MSD), skin-to-stone distance, and SHI were obtained on NCCT. Patients were classified into the low and high SHI groups using mean SHI and compared. One-session success rate in the high SHI group was better than in the low SHI group (74.3% vs. 63.9%, P = 0.008). Multivariate logistic regression analyses revealed that smaller stone size (OR 0.889, 95% CI: 0.841–0.937, P < 0.001), lower MSD (OR 0.995, 95% CI: 0.994–0.996, P < 0.001), and higher SHI (OR 1.011, 95% CI: 1.008–1.014, P < 0.001) were independent predictors of one-session success. The radiologic heterogeneity of urinary stones or SHI was an independent predictor for SWL success in patients with ureteral calculi and a useful clinical parameter for stone fragility.

Optimal Skin-to-Stone Distance Is a Positive Predictor for Successful Outcomes in Upper Ureter Calculi following Extracorporeal Shock Wave Lithotripsy: A Bayesian Model Averaging Approach

Objectives

To investigate whether skin-to-stone distance (SSD), which remains controversial in patients with ureter stones, can be a predicting factor for one session success following extracorporeal shock wave lithotripsy (ESWL) in patients with upper ureter stones.

Patients and Methods

We retrospectively reviewed the medical records of 1,519 patients who underwent their first ESWL between January 2005 and December 2013. Among these patients, 492 had upper ureter stones that measured 4–20 mm and were eligible for our analyses. Maximal stone length, mean stone density (HU), and SSD were determined on pretreatment non-contrast computed tomography (NCCT). For subgroup analyses, patients were divided into four groups. Group 1 consisted of patients with SSD<25^th percentile, group 2 consisted of patients with SSD in the 25^th to 50^th percentile, group 3 patients had SSD in the 50^th to 75^th percentile, and group 4 patients had SSD≥75^th percentile.

Results

In analyses of group 2 patients versus others, there were no statistical differences in mean age, stone length and density. However, the one session success rate in group 2 was higher than other groups (77.9% vs. 67.0%; P = 0.032). The multivariate logistic regression model revealed that shorter stone length, lower stone density, and the group 2 SSD were positive predictors for successful outcomes in ESWL. Using the Bayesian model-averaging approach, longer stone length, lower stone density, and group 2 SSD can be also positive predictors for successful outcomes following ESWL.

Conclusions

Our data indicate that a group 2 SSD of approximately 10 cm is a positive predictor for success following ESWL.

Noncontrast computed tomography factors that predict the renal stone outcome after shock wave lithotripsy

OBJECTIVES

Extracorporeal shock wave lithotripsy (ESWL) is a popular treatment for nephrolithiasis. We took advantage of noncontrast abdominal computed tomography (NCCT) to search the possible prognostic factors including abdominal fat distribution influencing stone-free rate.

METHODS

From August 2008 to August 2010, 145 patients who had renal calculus and had undergone ESWL were retrospectively reviewed. All of them received NCCT assessment before ESWL and were followed up after 1 month for stone clearance. These patients were divided into two groups: one was the stone-free group and the other was the residual-stone group. Affecting parameters included stone size, location, stone surface area, Hounsfield unit density (HU density), skin-to-stone distance (SSD), and abdominal fat area as analyzed between these two groups.

RESULTS

Of 145 patients, 70 were stone-free and 75 had residual stone after ESWL treatment and 1-month follow-up. From univariate analysis, stone size, HU density, SSD, and stone surface area were significant predicting factors for ESWL success. On multivariate analysis, the important factors influencing ESWL outcomes were HU density and stone surface area (odds ratio 1.002 vs. 77.18, respectively; P<.05). Abdominal fat accumulation and distribution had no significant difference between these two groups.

CONCLUSION

This study revealed that stone size, HU density, SSD, and stone surface area were associated with stone-free rate after ESWL treatment. Therefore, these factors could be used to assess the feasibility of ESWL before deciding the treatment strategy. Abdominal fat distribution had no significant impact on ESWL outcome for renal stones.

Impact of colic pain as a significant factor for predicting the stone free rate of one-session shock wave lithotripsy for treating ureter stones: a Bayesian logistic regression model analysis

Purpose

This study was conducted to evaluate colic pain as a prognostic pretreatment factor that can influence ureter stone clearance and to estimate the probability of stone-free status in shock wave lithotripsy (SWL) patients with a ureter stone.

Materials and Methods

We retrospectively reviewed the medical records of 1,418 patients who underwent their first SWL between 2005 and 2013. Among these patients, 551 had a ureter stone measuring 4–20 mm and were thus eligible for our analyses. The colic pain as the chief complaint was defined as either subjective flank pain during history taking and physical examination. Propensity-scores for established for colic pain was calculated for each patient using multivariate logistic regression based upon the following covariates: age, maximal stone length (MSL), and mean stone density (MSD). Each factor was evaluated as predictor for stone-free status by Bayesian and non-Bayesian logistic regression model.

Results

After propensity-score matching, 217 patients were extracted in each group from the total patient cohort. There were no statistical differences in variables used in propensity- score matching. One-session success and stone-free rate were also higher in the painful group (73.7% and 71.0%, respectively) than in the painless group (63.6% and 60.4%, respectively). In multivariate non-Bayesian and Bayesian logistic regression models, a painful stone, shorter MSL, and lower MSD were significant factors for one-session stone-free status in patients who underwent SWL.

Conclusions

Colic pain in patients with ureter calculi was one of the significant predicting factors including MSL and MSD for one-session stone-free status of SWL.

Predicting stone composition before treatment - can it really drive clinical decisions?

Introduction

Determination of stone composition is considered to be crucial for the choice of an optimal treatment algorithm. It is especially important for uric acid stones, which can be dissolved by oral chemolysis and for renal stones smaller than 2 cm, which can be treated with extracorporeal shockwave lithotripsy (ESWL).

Material and methods

This short review identifies the latest papers on radiological assessment of stone composition and presents a comprehensive evaluation of current scientific findings.

Results

Stone chemical composition is difficult to predict using standard CT imaging, however, attenuation index measured in Hounsfield units (HU) is related to ESWL outcome. Stone density >1000 HU can be considered predictive for ESWL failure. It seems that stone composition is meaningless in determining the outcome of ureterolithotripsy and percutaneous surgery. Alternative imaging techniques such as Dual–Energy CT or analysis of shape, density and homogeneity of stones on plain X–rays are used as promising methods of predicting stone composition and ESWL outcome.

Conclusions

New imaging techniques facilitate the identification of uric acid stones and ESWL–resistant stones. Therefore, they may help in selecting the best therapeutic option.

The success of extracorporeal shock-wave lithotripsy based on the stone-attenuation value from non-contrast computed tomography

Objective

To determine the utility of the urinary stone-attenuation value (SAV, in Hounsfield units, HU) from non-contrast computed tomography (NCCT) for predicting the success of extracorporeal shock-wave lithotripsy (ESWL).

Patients and methods

The study included 305 patients with renal calculi of ⩽30 mm and upper ureteric calculi of ⩽20 mm. The SAV was measured using NCCT. Numerical variables were compared using a one-way analysis of variance with posthoc multiple two-group comparisons. Univariate and multivariate regression analysis models were used to test the preferential effect of the independent variable(s) on the success of ESWL.

Results

Patients were grouped according to the SAV as group 1 (⩽500 HU, 81 patients), group 2 (501–1000 HU, 141 patients) and group 3 (>1000 HU, 83 patients). ESWL was successful in 253 patients (83%). The rate of stone clearance was 100% in group 1, 95.7% (135/141) in group 2 and 44.6% (37/83) in group 3 (P = 0.001).

Conclusions

The SAV value is an independent predictor of the success of ESWL and a useful tool for planning stone treatment. Patients with a SAV ⩾956 HU are not ideal candidates for ESWL. The inclusion criteria for ESWL of stones with a SAV <500 HU can be expanded with regard to stone size, site, age, renal function and coagulation profile. In patients with a SAV of 500–1000 HU, factors like a body mass index of >30 kg/m² and a lower calyceal location make them less ideal for ESWL.