Prognostic factors of success of extracorporeal shock wave lithotripsy (ESWL) in the treatment of renal stones

What Is the Ideal Treatment for 20-30 mm Kidney Stones? Comparative Outcomes of 1197 Patients

Background: The purpose of this study is to compare the efficacy and safety of extracorporeal shockwave lithotripsy (SWL), retrograde intrarenal surgery (RIRS), mini-percutaneous nephrolithotomy (mPNL), and standard-percutaneous nephrolithotomy (stPNL) for the treatment of 20-30 mm kidney stones. Methods: The records of 1197 patients (SWL = 149, RIRS = 205, mPNL = 525, and stPNL = 318) from 8 centers were reviewed retrospectively. Four procedures were compared for stone-free rates (SFRs), auxiliary treatment, and associated complications. Results: Initial SFRs were 43.6%, 54.6%, 86.7%, and 87.7% in SWL, RIRS, mPNL, and stPNL, respectively (P < .001), whereas the final SFRs were 71.8%, 80%, 90.5%, and 89.6% (P < .001). The rate of auxiliary treatment in the groups was 38.3%, 26.8%, 5%, and 4.4%, respectively (P < .001). The initial and final SFRs in the mPNL and stPNL groups were higher than those in SWL and RIRS groups (P < .001). The rate for auxiliary treatment was lower in the mPNL and stPNL groups (P < .001). The operation time was longer in the RIRS group (P = .005). According to the Clavien-Dindo classification, the complication rate in the SWL group was lower than that in the surgical approaches (P < .001); however, no statistical difference was detected between RIRS, mPNL, and stPNL groups. mPNL and stPNL had a higher success rate than RIRS or SWL for treating 20-30 mm kidney stones. Conclusion: In the treatment of 2-3 cm renal stones, RIRS and PNL were more effective than SWL to obtain a better SFR and less auxiliary treatment rate. Compared with RIRS, mPNL and stPNL provided a higher SFR with similar complication rates.

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.

Can we predict the ancillary treatments after extracorporeal shockwave lithotripsy for renal and upper ureteral stones?

OBJECTIVE

To quantify the predictors for the ancillary treatments after extracorporeal shock wave lithotripsy (SWL) for renal and upper ureteral stones.

MATERIALS AND METHODS

From January 2014 to January 2017, patients undergoing SWL using an electromagnetic lithotripter machine (Compact Delta; Dornier MedTech GmbH, Wessling, Germany) for renal and upper ureteral stones ≤ 20 mm were retrospectively reviewed. All patients underwent CT urography prior to SWL. The cohort was subdivided into three groups according to stone attenuation values in Hounsfield Units (HU). Group I; HU < 500 (n = 20), group II; HU 500-1000 (n = 51) and group III; HU ≥ 1000 (n = 180). The parameters included for multivariate analysis were stone size, location, multiplicity, stone attenuation value, number of shocks and stone clearance rate by 3 months. The ancillary treatments were ureteroscopy (URS), ureteral stenting and hospital readmission for pain or fever.

RESULTS

A total of 251 patients were included in the study. The overall SWL success rate was 92.4%. Mean stone size was 10.9 ± 2.1, 11.6 ± 3 and 11.4 ± 3.6 mm and mean stone attenuation values were 364 ± 125, 811 ± 154 and 1285 ± 171 HU for groups I, II and III respectively. The stone clearance rates by 3 months were 96%, 92% and 88.4% for groups I, II and III respectively. On subgroup analysis, group III required ancillary treatments in 70% of patients whereas group I, II, did not require any ancillary treatments. On multivariate analysis, stone multiplicity, stone location (lower calyceal stones) and HU were independent significant predictors for the need for ancillary treatments after SWL (p values < 0.05).

CONCLUSIONS

Patients with stone attenuation value (HU) > 1000, multiple stones and/or lower calyceal stones have higher risk to necessitate ancillary treatments after SWL. These patients would likely benefit from upfront endoscopic lithotripsy for treating symptomatic renal or upper ureteral stones.

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.

Effectiveness and Safety of Ureteroscopic Lithotripsy in Young, Old-Old, and Oldest Old Patients

Objectives: To investigate the efficacy and safety of ureteroscopic lithotripsy (URSL) in young, old-old, and oldest old patients. Materials and Methods: We enrolled 157 patients who underwent URSL. We divided the patients into young (<65 years), old-old (65-84 years), and oldest old (≥85 years) groups and compared the safety of surgery between young vs old-old and young vs oldest old, separately. Results: In the <65 group, 65 to 85 group, and ≥85 group, respectively, the mean stone diameters were 8.9 ± 4.9, 10.8 ± 7.7, and 11.4 ± 6.3 mm; mean operative time was 76.6 ± 33.1, 86.7 ± 44.7, and 84.0 ± 44.5 min; the stone-free rates were 95.9%, 94.4%, and 96.3%; and the complication rates were 8.2%, 9.8%, and 3.7%. Conclusions: In this study, we showed the feasibility and safety of URSL for elderly people. Although oldest old (≥85 years) people had multiple comorbidities with low performance status, URSL could be performed with acceptable complication rates. Clinical Trial Registration Number: 1809-1.

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.

Comparison of different shock wave frequencies on stone disintegration in extracorporeal shock wave lithotripsy; 60, 80 and 100/min

Background

We know that SWL started on February 07, 1980, by Christian Chaussy with a wide range of indications. Complication rate has always remained very low and usually limited to minor side effects and complications. This study shows the impact of different shock wave release frequencies 60, 80 & 100/min on disintegration of renal stones.

Methods

A total number of 210 patients with mean age (40 ± 15) years with renal stone who were candidate for SWL divided into 3 groups each are 70 patients on rate 60,80 and 100 per min), Chi-Square test, Fisher’s exact test used in the study.

Results

Complete stone clearance( defined as complete stone free) was obtained in 184 patients 87.6% after one session, the highest success rate 94.3% were obtained in the second group of patients ( with shock wave frequency 80/min) followed by the first group 87.1% (with shock wave frequency 60/min), and patients with highest frequency (100/min) had the lowest success rate 81.4%.

Conclusions

The best option is using intermediate shock wave rate 80/min to obtain highest success rate and mild pain. Using high rate 100/min is not favorable due to least disintegration rate with highest pain. Using rate 60/min shows less success than rate 80/min despite it less painful.

Factors affecting success in the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy in adult patients

The aim of the study was to analyze the factors predicting success for the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy (SWL) in adult patients. Between January 2014 and December 2018, 480 adult patients in total underwent SWL and data were retrospectively evaluated. Patients with multiple ureteral stones, solitary kidney, congenital abnormality, skeletal system abnormality, history of previous urinary system surgery and SWL, renal insufficiency, patients who could not tolerate SWL and pediatric patients were excluded from the study. The remaining 415 patients were divided into two groups as success (Group 1, n = 307) and failure (Group 2, n = 108). The overall success rate was 73.9%. The values of stone size, Hounsfield Unit (HU), skin to stone distance (SSD), ureteral wall thickness (UWT), proximal ureter diameter, renal pelvis diameter, hydronephrosis grade, and duration of renal colic were significantly higher in Group 2 compared to Group 1. In binary logistic regression analyses, HU, UWT, and proximal ureter diameter were found to be independent predictors. HU, UWT, and proximal ureter diameter had sensitivity and specificity of 92-92%, 88-23%, and 87-46%, with cutoff values of 740 HU, 2.5 mm and 8.5 mm, respectively. The area under the curve values were 0.96, 0.97, and 0.96 for HU, UWT, and proximal ureter diameter, respectively. The CT-based parameters, including HU, UWT, and proximal ureter diameter are independent predictive factors with excellent accuracy for the treatment of proximal ureteral stones larger than 1 cm with SWL in adult patients. Based on these factors, SWL can be considered for proximal ureteral stones larger than 1 cm.

The alternating bidirectional versus the standard approach during shock wave lithotripsy for upper lumbar ureteric stones: a randomized controlled trial

PURPOSE

To compare the outcome of shock wave lithotripsy (SWL) for upper lumbar ureteric stones using the alternating bidirectional approach versus the standard approach during the first session.

METHODS

Our study was a randomized controlled trial including patients with single radio-opaque stone < 1 cm located in the upper lumbar ureter (from the ureteropelvic junction till the level medial to the lower margin of the kidney). SWL was conducted using electromagnetic Dornier Gemini Lithotripter. In group 1, patients were treated with the alternating under and over-table approach during the first session only and if other sessions were needed, the standard under-table approach was used. In group 2, patients were treated with the standard under-table approach during all sessions. Stone disintegration after the first session was assessed by kidney-ureter-bladder X-ray, renal ultrasonography and noncontrast computed tomography. Moreover, the incidence and severity of postoperative complications were evaluated.

RESULTS

Forty-eight patients in each group completed the study. Patient demographics and stone characteristics were comparable in both groups. Complete disintegration was achieved in 41.7% of patients in group 1 versus 18.8% in group 2 (P = 0.021). Stone-free rate (SFR) was 58.3% and 20.8% in group 1 and 2 respectively (P = 0.001). The mean session time was 56.42 min in group 1 versus 46.35 min in group 2 (P < 0.001). There was no significant difference in postoperative complications.

CONCLUSION

Stone disintegration and SFR after the first SWL session are higher when using the alternating bidirectional approach for upper lumbar ureteric stones at the expense of longer procedural duration.

TRIAL REGISTRATION

ClinicalTrials identifier (ID: NCT03243682), clinicaltrials.gov.

Risk factors for recurrent urolithiasis in children

PURPOSE

To identify risk factors associated with recurrent kidney stones in a paediatric cohort in a Belgian tertiary centre.

STUDY DESIGN AND METHODS

Medical records of children with the first episode of urolithiasis between 1998 and 2016, followed at Ghent University Hospital initially and at least one-year follow-up were retrospectively reviewed. Patient characteristics, past medical history, presenting symptoms, the results of laboratory investigations and the applied management strategy were analysed. The significant variables from the univariate analysis were integrated into a backward conditional multivariate model.

RESULTS

Ninety-seven children were included in the analysis, of which 33 (34%) presented with at least one episode of stone recurrence. In the univariate analysis, body mass index (BMI) > 85th percentile and asymptomatic stones at initial presentation were associated with 1.8 and 0.1 times lower risk of recurrent stones, respectively (p = 0.020, 95% confidence interval (CI):0.368-8.749 and p = 0.017, 95% CI:0.014-0.921). In contrast, immobilization resulted in a 10-times higher risk (p = 0.002, 95% CI:1.968-50.005) and the need for technical intervention was associated with a 3.2- times higher risk (p = 0.017, 95% CI:1.297-8.084) of developing recurrent stones. On multivariate analysis only BMI >85th percentile was associated with a 15 times lower risk of stone recurrence (p = 0.030, 95% CI:0.006-0.739).

DISCUSSION

A possible explanation of reduced risk in patients with a BMI > 85th percentile may lie in a different metabolic profile. Immobilization as a risk factor can be explained by calcium metabolism, which is influenced by immobilization due to fractures, paralysis or motor disability because it causes resorption of the skeleton resulting in elevated blood calcium levels. This study showed that patients who presented without symptoms when the stones first occurred were less likely to have recurring kidney stones compared with patients with symptoms at initial presentation. When technical intervention was needed, we believe this is partly due to a larger stone burden, however we could not find an evidence-based explanation. The institutional protocol, which allowed to create a database with a limited number of patients, was lost to follow-up. Despite the retrospective setting some data were missing. There might also be a bias because the patients were followed-up at a tertiary centre. Possibly, our conclusions cannot be generalized toward the entire paediatric population.

CONCLUSION

Of all the factors investigated in our cohort, BMI >85 th percentile and asymptomatic stones are associated with a lower risk of stone recurrence. Conversely, immobilized patients and those who require technical intervention at initial presentation may benefit from an intense follow-up after the first episode of urolithiasis.

Predicting shockwave lithotripsy outcome for urolithiasis using clinical and stone computed tomography texture analysis variables

We aimed to develop and evaluate a statistical model, which included known pre-treatment factors and new computed tomography texture analysis (CTTA) variables, for its ability to predict the likelihood of a successful outcome after extracorporeal shockwave lithotripsy (SWL) treatment for renal and ureteric stones. Up to half of patients undergoing SWL may fail treatment. Better prediction of which cases will likely succeed SWL will help patients to make an informed decision on the most effective treatment modality for their stone. 19 pre-treatment factors for SWL success, including 6 CTTA variables, were collected from 459 SWL cases at a single centre. Univariate and multivariable analyses were performed by independent statisticians to predict the probability of a stone free (both with and without residual fragments) outcome after SWL. A multivariable model had an overall accuracy of 66% on Receiver Operator Curve (ROC) analysis to predict for successful SWL outcome. The variables most frequently chosen for the model were those which represented stone size. Although previous studies have suggested SWL can be reliably predicted using pre-treatment factors and that analysis of CT stone images may improve outcome prediction, the results from this study have not produced a useful model for SWL outcome prediction.

Assessing Cost-Effectiveness of New Technologies in Stone Management

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

Ureteroscopy and stone treatment in the elderly (≥70 years): prospective outcomes over 5- years with a review of literature

Objective:

To assess outcomes of ureteroscopy for treatment of stone disease in the elderly. Ureteroscopy (URS) is an increasingly popular treatment modality for urolithiasis and its applications are ever expanding with the development of newer technologies. Its feasibility and outcomes within the elderly population to our knowledge remain under-reported.

Materials and Methods:

We examined the patient demographics and surgical outcomes from our prospective database for patients ≥70 years who underwent URS for urolithiasis, in a 5-year period between March 2012 and December 2016.

Results:

A total of 110 consecutive patients underwent 121 procedures (1.1 procedure/patient) with a mean age of 77.2 years (range: 70-91 years). Stone location was in the kidney/ pelviureteric junction (PUJ) in 29%, ureter in 37% and in multiple locations in 34%. The initial and final stone free rate (SFR) was 88% and 97% respectively. While 73% were done as true day case procedures, 89% patients were discharged within 24 hours. Eleven patients (9%) underwent complications of which 10 were Clavien I/II including acute urinary retention, urinary tract infection, stent symptoms and pneumonia. One patient underwent Clavien IV complication where they needed intensive care unit admission for urosepsis but fully recovered and were discharged home subsequently.

Conclusion:

Ureteroscopy is a safe and effective method of managing urolithiasis in elderly patients. Although most patients are discharged within 24-hours, consideration needs to be made for patients where social circumstances can impact their discharge planning.

The role of super-mini percutaneous nephrolithotomy (SMP) in the treatment of symptomatic lower pole renal stones (LPSs) after the failure of shockwave lithotripsy (SWL) or retrograde intrarenal surgery (RIRS)

To assess the safety and efficacy of super-mini percutaneous nephrolithotomy (SMP) in the treatment of symptomatic lower pole renal stones (LPSs) after the failure of shockwave lithotripsy (SWL) or retrograde intrarenal surgery (RIRS), we retrospectively evaluated 44 patients with symptomatic LPSs with previously failed SWL or RIRS and consequently underwent SMP from October 2014 to March 2016. The percutaneous renal access was performed 12-14F with C-arm fluoroscopy or ultrasonographic guidance. Stone disintegration was performed using either Holmium laser or pneumatic lithotripter. Perioperative parameters along with operations were assessed in detail. A total of 44 patients (mean age 49.1 ± 13.7 years) were included in the study. Stone size was 18.4 ± 6.0 mm (range 9-29), operative time was 63.9 ± 32.7 min (range 14-145) and hospital stay was 2.8 ± 1.2 days (range 1-5). The hemoglobin drop was 12.4 ± 8.8 g/L (range 0-31), and no patients required blood transfusion. Complete stone-free status was achieved in 40 (90.9%) patients. Clinically insignificant residual fragments were observed in three (6.8%) patients and only one (2.3%) patient had a 6 mm residual calculus. A total of three minor complications (urinary tract infection, hemorrhage resolved by hemostatics and renal colic requiring analgesics) were observed postoperatively. For symptomatic LPSs after the failure of SWL or RIRS, SMP is a safe and efficient auxiliary option and even might be an alternative to SWL or RIRS, while further considering the stone-free rates and stone-related events.

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.

Immediate versus delayed shockwave lithotripsy for inaccessible stones after uncomplicated percutaneous nephrolithotomy

Objective

To evaluate the efficacy and safety of immediate versus delayed shockwave lithotripsy (SWL) for inaccessible stones after uncomplicated percutaneous nephrolithotomy (PCNL).

Patients and methods

Between December 2011 and June 2014, patients with residual inaccessible stones after uncomplicated PCNL were prospectively randomised into two treatment groups; Group I, immediate SWL and Group II, delayed SWL at 1 week after PCNL. Patients with residual stones of ⩾1.5 cm, a stone density of >1000 Hounsfield units and body mass index of >40 kg/m² were excluded from the study. The following data were reported: patients’ demographics, stone characteristics after PCNL, hospital stay, perioperative complications, stent duration, and stone-free rate (SFR).

Results

In all, 84 patients (51 males and 33 females) with mean (SD) age of 39 (8.5) years were included in the study. Group I included 44 patients, whilst Group II included 40 patients. There was no statistically significant difference amongst the groups for patients’ demographics, stone characteristics, and perioperative complications. The hospital stay was significantly shorter in Group I, at a mean (SD) of 34 (3.7) vs 45 (2.9) h (P < 0.001). The duration of ureteric stenting was significantly lower in Group I as compared to Group II, at a mean (SD) of 12 (4.2) vs 25 (3.5) days (P < 0.001). The SFR was 93.2% and 95% in Groups I and II, respectively (P = 0.9).

Conclusions

Immediate SWL after PCNL is as effective and safe as delayed SWL with a lesser hospital stay and duration of ureteric stenting.

Comparison of shockwave frequencies of 30 and 60 shocks per minute for kidney stones: a prospective randomized study

OBJECTIVE

One of the factors that determines the treatment success of shockwave lithotripsy (SWL) is the frequency of the shockwaves during the procedure. This study compared the efficacy and pain perception of shockwave frequencies at 30 versus 60 shocks/min for kidney stones.

MATERIALS AND METHODS

From August 2013 to May 2015, 160 patients with solitary, radiopaque kidney stones were randomized to SWL at 30 shocks/min (group 1) or 60 shocks/min (group 2), with 80 patients in each group. The primary outcome measure was success rate at 3 months after the last SWL session. The secondary outcome measure was pain perception during the procedures.

RESULTS

Of the 160 randomized patients, data for a total of 148 patients (74 patients in group 1 and 74 patients in group 2) were analyzed, after the exclusion of the patients lost to follow-up or who required secondary intervention within 3 months. There was no statistically significant difference between the two groups in terms of the success rate at 3 months (68.9% vs 71.6%, p = .719). However, the mean visual analogue scale scores of all the sessions were significantly higher in group 1 than in group 2 (5.83 vs 4.06, p < .05). Stone location, especially the lower calyceal location, was the only significant negative predictor for success according to multivariate logistic regression analysis.

CONCLUSIONS

The success rate was similar between these two frequencies. However, pain perception was significantly higher at 30 than at 60 shocks/min.

The success of shock wave lithotripsy (SWL) in treating moderate-sized (10-20 mm) renal stones

Many centres favour endourological management over shock wave lithotripsy (SWL) in the management of moderate-sized (10-20 mm) renal stones. International guidelines support all available modalities for the treatment of these stones. The aim of this study was to evaluate the efficacy of SWL in the treatment of 10- to 20-mm renal stones. From January 2013 to October 2014, all patients with a renal stone measuring between 10 and 20 mm in maximum diameter on CT scan that were eligible for lithotripsy were included. 130 consecutive patients were evaluated. Demographics, location of stone within the kidney, number of SWL sessions and treatment outcomes were analysed. Treatment success was classified into complete stone clearance and the presence of clinically insignificant residual fragments <4 mm (CIRF). 119 patients (92 %) completed treatment and radiological follow-up. Eleven patients were excluded due to incomplete follow-up data. The mean age was 56.8 (23-88). Male to female ratio was 1.9:1 (78:41) and the mean BMI was 28.4 (17.9-58). The mean stone size was 12.8 mm (10-14 mm: n = 87; 15-20 mm: n = 32). The mean number of treatments was 2.14 and 2.82 for stones 10-14 and 15-20 mm, respectively. Overall treatment success was 66.4 % (combined complete stone clearance and CIRFs). Subdivided by stone size <15 mm and ≥15 mm, the success rate was 70.4 and 53.1 %, respectively. The treatment success by stone location was 65, 64 and 70 % for upper, middle and lower pole stones, respectively and 67 % for PUJ stones. For those who failed SWL treatment, the majority 50 % (n = 20) were managed expectantly, 42.5 % (n = 17) required URS, and 7.5 % (n = 3) required PNL. This study suggests that SWL has an efficacy for treating larger renal stones (10-20 mm) that is equivalent to success rates for smaller stones in other series. As a low-risk and non-invasive procedure SWL should be considered a first-line treatment for these stones.

Does ureteral stenting matter for stone size? A retrospectıve analyses of 1361 extracorporeal shock wave lithotripsy patients

Introduction

The aim of our study was to determine the efficacy of ureteral stents for extracorporeal shock wave lithotripsy (SWL) treatment of pelvis renalis stones and to compare the results and complications in stented and non-stented patients.

Material and methods

Between 1995 and 2011, 1361 patients with pelvis renalis stones were treated with SWL. Patients were subdivided into three groups according to stone burden: ≤1 cm² (group 1; n = 514), 1.1 to 2 cm² (group 2; n = 530) and >2 cm² (group 3; n = 317). Each group was divided into subgroups of patients who did and did not undergo ureteral stent implantation before SWL treatment. The efficacy of treatment was evaluated by determining the effectiveness quotient (EQ). Statistical analysis was performed by chi-square, Fisher's exact and Mann-Whitney U tests.

Results

Of the 514, 530 and 317 patients in groups 1, 2 and 3 respectively, 30 (6%), 44 (8%) and 104 (33%) patients underwent auxiliary stent implantation. Steinstrasse rates did not differ significantly between stented and non-stented patients in each group. The EQ was calculated as 62%, 33% and 70% respectively in non-stented, stented and totally for group 1. This ratio calculated as 58%, 25% and 63% for group 2 and 62%, 26% and 47% for group 3. Stone-free rates were significantly higher for non-stented than for stented patients in groups 2 and 3.

Conclusions

Stone free rates are significantly higher in non-stented than in stented patients with pelvis renalis stones >1 cm², whereas steinstrasse rates are not affected.

Is Micropercutaneous Nephrolithotomy Technique Really Efficacicous for the Treatment of Moderate Size Renal Calculi? Yes

OBJECTIVE

To present our clinical experiences with micropercutaneous nephrolithotomy in the treatment of moderate-sized renal calculi from a single center.

METHODS

We retrospectively evaluated the patients with moderate-sized renal calculi who underwent micro-percutaneous nephrolithotomy between December 2012 and Septermber 2013.

RESULTS

A total of 68 patients and 70 renal units underwent microperc procedure. Mean age of patients was 41.4 ± 18.8. The mean stone size was 122 ± 83 mm(2). The operations were performed under spinal anesthesia in 89.7% of the patients. Stone-free rate was 95.7 % (67/70). Clinically significant residual fragments were observed in three patients. The average duration of operation and mean fluoroscopy time was 40 ± 23 min and 108 ± 72 s, respectively. The mean postoperative drop in hemoglobin was 0.95 ± 0.7 while no patient required blood transfusion. Patients were discharged after an average hospitalization time of 27.5 ± 12.4 h. A total of 4 complications (5.7%), including urinary tract infection (Clavien I) in one patient and renal colics requiring stent insertion (Clavien IIIa) in three patients, were observed postoperatively.

CONCLUSION

Microperc technique is safe, feasible, and efficacious. We suggest that micro-percutaneous nephrolithotomy should be considered for the treatment of moderate-sized renal stones as an alternative to SWL and RIRS failures and also may be considered even primarily.

Extracorporeal shock wave lithotripsy in the treatment of renal and ureteral stones

The use of certain technical principles and the selection of favorable cases can optimize the results of extracorporeal shock wave lithotripsy (ESWL). The aim of this study is to review how ESWL works, its indications and contraindications, predictive factors for success, and its complications. A search was conducted on the Pubmed® database between January 1984 and October 2013 using "shock wave lithotripsy" and "stone" as key-words. Only articles with a high level of evidence, in English, and conducted in humans, such as clinical trials or review/meta-analysis, were included. To optimize the search for the ESWL results, several technical factors including type of lithotripsy device, energy and frequency of pulses, coupling of the patient to the lithotriptor, location of the calculus, and type of anesthesia should be taken into consideration. Other factors related to the patient, stone size and density, skin to stone distance, anatomy of the excretory path, and kidney anomalies are also important. Antibiotic prophylaxis is not necessary, and routine double J stent placement before the procedure is not routinely recommended. Alpha-blockers, particularly tamsulosin, are useful for stones >10mm. Minor complications may occur following ESWL, which generally respond well to clinical interventions. The relationship between ESWL and hypertension/diabetes is not well established.

Cross-sectional imaging of iatrogenic complications after extracorporeal and endourological treatment of urolithiasis

Extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL) and ureteroscopy (URS) currently represent the mainstay treatment options for the vast majority of patients with urolithiasis, with limited contraindications and high success rates. However, minimally invasive extracorporeal and endourological treatments are associated with a non-negligible morbidity including occasional life-threatening occurrences. These complications represent a source of concern for urologists since they may result in prolonged hospitalisation, need for surgical, endoscopic or interventional treatment, long-term renal impairment, and sometimes even medical malpractice claims. Due to the increasing prevalence of urolithiasis and the large number of therapeutic procedures performed, in hospitals with active urologic practices radiologists are increasingly requested to investigate suspected post-procedural complications following ESWL, PCNL or ureteroscopic stone removal. Based upon our experience, this pictorial essay provides an overview of current extracorporeal and endourological treatment modalities for urolithiasis, including indications and possible complications according to the most recent guidelines from the European Association of Urology (EAU). Afterwards, we review the clinical features and cross-sectional imaging appearances of common and unusual complications with case examples, including steinstrasse, subcapsular, perirenal and suburothelial haemorrhages, severe urinary tract infections (such as pyeloureteritis, pyelonephritis, renal abscesses and pyonephrosis), ureteral injuries and delayed strictures.

Teaching points

• Extracorporeal lithotripsy, percutaneous nephrolitotomy and ureteroscopy allow treating urolithiasis.

• Minimally invasive extracorporeal and endourological treatment have non-negligible morbidity.

• Multidetector CT allows confident assessment of stone-free status and postprocedural complications.

• Main complications include steinstrasse, bleeding, severe infections, ureteral injuries and strictures.

• Imaging triage allows the choice among conservative, surgical, endoscopic or interventive treatment.

Kidney stones over 2 cm in diameter-between guidelines and individual approach

The prevalence of urolithiasis has been observed to increase during last decades. Kidney stones over 2 cm in diameter are the common urologic problem. European and American Associations of Urology has published guidelines on Urolithiasis and presented the most effective tools to treat large stones. On the other hand many experienced endourologic centres choose other modalities from their armamentarium. All treatment methods are characterized by their efficacy and safety which are usually inversely proportional. It is crucial for patients and physicians to find a golden mean. Percutaneous lithotripsy is still considered treatment of choice with more than 95% efficacy. Less invasive retrograde intrarenal surgery is also less effective, but burdened with lower complication rate. Extracorporeal shockwave lithotripsy is feasible in paediatric patients with acceptable stone free rates. Open surgery (pylolithotomy and anatrophic nephrolithotomy) are almost obsolete techniques. All methods have their pros and cons. Physicians should share decisions regarding treatment modalities with patients.

Comparison of shock wave lithotripsy, flexible ureterorenoscopy and percutaneous nephrolithotripsy on moderate size renal pelvis stones

To compare success and complication rates of shock wave lithotripsy (SWL), flexible ureterorenoscopy (F-URS) and percutaneous nephrolithotripsy (PNL) according to modified clavien grading system of renal pelvis stones between 1 and 2 cm. The results of 149 patients were evaluated retrospectively. Patients were divided into three groups as 52 for SWL, 47 for F-URS and 50 for PNL. Complications were evaluated by modified Clavien grading system. In the first group, stone-free rates after a mean of 2, 6 sessions was 86 % (45/52). In Group 2, this ratio was 91.4 % (43/47), and in Group 3, it was 98 % (49/50). The success rate in Group 3 was significantly higher than other groups. Complication rates for Group 1, 2 and 3 were 7.6 % (4/52), 6.3 % (3/47) and 12 % (6/50), respectively. Although PNL was the most successful technique compared with other techniques, complications were also higher in this group. Even though PNL is the most successful, it should be performed for selected patient groups and indications should be carefully evaluated.

Extracorporeal shock wave lithotripsy for management of residual stones after ureterolithotripsy versus mini-percutaneous nephrolithotomy: a retrospective study

Purpose

To compare the efficacy of extracorporeal shock wave lithotripsy in managing residual stones after ureterolithotripsy and mini-percutaneous nephrolithotomy.

Materials and Methods

A retrospective study was carried out of 71 patients with proximal urinary tract stones (greater than 10 mm) who underwent ureterolithotripsy or mini-percutaneous nephrolithotomy at a single institution from 2009 to 2011. The 71 patients were divided into two groups: group I (n = 37) comprised patients who underwent ureterolithotripsy, and group II (n = 34) comprised patients who underwent mini-percutaneous nephrolithotomy. Clinical characteristics, stone-free rates, stone demographics, and complications were evaluated.

Results

The overall stone-free rate was 90.1%. The stone-free rates in groups I and II were 97.3% and 82.4%, respectively. There was a statistically significant difference in the stone-free rates between groups I and II (P = 0.035). Neither serious intraoperative nor postoperative complications were observed. No significant difference in complications was observed between the two groups (P = 0.472).

Conclusions

The results of our study suggest that extracorporeal shock wave lithotripsy is an effective and safe auxiliary procedure for managing residual stones after primary endoscopic surgery. This procedure is associated with a satisfactory stone-free rate and a low complication rate, particularly for residual stones after ureteroscopic procedures.

Impact of stone density on outcomes in percutaneous nephrolithotomy (PCNL): an analysis of the clinical research office of the endourological society (CROES) pcnl global study database

OBJECTIVE

This study aimed to explore the relationship between stone density and outcomes of percutaneous nephrolithotomy (PCNL) using the Clinical Research Office of the Endourological Society (CROES) PCNL Global Study database.

MATERIAL AND METHODS

Patients undergoing PCNL treatment were assigned to a low stone density [LSD, ≤ 1000 Hounsfield units (HU)] or high stone density (HSD, > 1000 HU) group based on the radiological density of the primary renal stone. Preoperative characteristics and outcomes were compared in the two groups.

RESULTS

Retreatment for residual stones was more frequent in the LSD group. The overall stone-free rate achieved was higher in the HSD group (79.3% vs 74.8%, p = 0.113). By univariate regression analysis, the probability of achieving a stone-free outcome peaked at approximately 1250 HU. Below or above this density resulted in lower treatment success, particularly at very low HU values. With increasing radiological stone density, operating time decreased to a minimum at approximately 1000 HU, then increased with further increase in stone density. Multivariate non-linear regression analysis showed a similar relationship between the probability of a stone-free outcome and stone density. Higher treatment success rates were found with low stone burden, pelvic stone location and use of pneumatic lithotripsy.

CONCLUSIONS

Very low and high stone densities are associated with lower rates of treatment success and longer operating time in PCNL. Preoperative assessment of stone density may help in the selection of treatment modality for patients with renal stones.

The role of microperc in the treatment of symptomatic lower pole renal calculi

BACKGROUND AND PURPOSE

The treatment of symptomatic lower pole (LP) calculi poses a challenge because of lower clearance rates. We present our experience with microperc in the treatment of LP renal calculi.

PATIENTS AND METHODS

We retrospectively evaluated the symptomatic patients with LP renal calculi who underwent microperc between August 2011 and June 2012 from two referral hospitals. Patients were included only in cases of failure after shockwave lithotripsy (SWL) or retrograde intrarenal surgery (RIRS) and according to patient preference. The percutaneous renal access was performed using the 4.8F "all-seeing needle" with C-arm fluoroscopy or ultrasonographic guidance with the patient in the prone position. Stone disintegration was established using a 200 μm holmium:yttrium-aluminum-garnet laser fiber.

RESULTS

A total of 21 patients (mean age 37.3 ± 20.1 years) with LP stone underwent microperc. The mean body mass index was 28.6 ± 6.0 kg/m(2), and the mean stone size was 17.8 ± 5.9 (9-29) mm. The duration of surgery and fluoroscopic screening was 62.8 ± 25.2 minutes and 150.5 ± 92.8 seconds, respectively. The patients were discharged after a mean 37.5 ± 14.4 hours of hospitalization time. The mean hemoglobin drop was 0.8 ± 0.6 (0.1-2.3) g/dL. Conversion to miniperc was necessitated in one patient with loss of vision. Stone-free status was achieved in 18 (85.7%) patients. Clinically insignificant residual fragments were observed in only one (4.8%). The procedure failed in two (9.5%) patients. A total of two minor complications (renal colic necessitating stent insertion and urinary tract infection) were observed postoperatively, none severe.

CONCLUSION

Microperc is a feasible and efficient treatment modality for symptomatic LP calculi. Our results provide that microperc might take a part in case of SWL and RIRS failures or as an alternative to percutaneous nephrolithotomy or RIRS in the management of symptomatic LP calculi.

Extracorporeal shock wave lithotripsy: What is new?

OBJECTIVES

Thirty years after its introduction, extracorporeal shockwave lithotripsy (ESWL) is still first-line treatment for more than half of all urinary tract stones, but machines and treatment strategies have significantly developed over time. In this review, we summarise the latest knowledge about the clinically important aspects of ESWL.

METHODS

We searched PubMed to identify relevant reports and the latest European Association of Urology guidelines, and standard urological textbooks were consulted.

RESULTS

New technical developments include: Twin-head and tandem-pulse shock-wave generators; wide-focus, low-pressure systems; optimised coupling; and automated location and acoustic tracking systems. Indications have been refined, making possible the identification of patients in whom ESWL treatment is likely to fail. By lowering the shock-wave rate, improving coupling, applying abdominal compression, power 'ramping' and postoperative medical expulsion therapy, treatment protocols have been optimised.

CONCLUSIONS

Promising new technical developments are under development, with the potential to increase the stone-free rate after ESWL. For optimal results, the refined indications need to be respected and optimised treatment protocols should be applied.

Is the gravity effect of radiographic anatomic features enough to justify stone clearance or fragments retention following extracorporeal shock wave lithotripsy (SWL)

We determined whether the gravity effect of radiographic anatomic features on the preoperative urography (IVP) are enough to predict fragments clearance after shock wave lithotripsy (SWL). A Total of 282 patients with mean age 45.8 ± 13.2 years (189 male, 93 female), who underwent SWL due to renal calculi between October 2005 and August 2009 were enrolled. The mean calculi load was 155.72 ± 127.66 mm². The patients were stratified into three groups: patients with pelvis calculi (group 1); patients with upper or middle pole calculi (group 2) and patients with lower pole calculi (group 3). Three angles on the pretreatment IVP were measured: the inner angle between the axis of the lower pole infundibular and ureteropelvic axis (angle I); the inner angle between the lower pole infundibular axis and main axis of pelvis-ureteropelvic (UP) junction point (angle II) and the inner angle between the lower pole infundibular axis and perpendicular line (angle III). Multivariate analysis was used to define the significant predictors of stone clearance. The overall success rate was 85.81%. All angles, sessions number, shock waves number and stone burden were significant predictors of success in patients in group 1. However, in group 2 only angle II and in group 3 angles I and II had significant effect on stone clearance. Radiographic anatomic features have significant role in determining the stone-free rate following satisfactory fragmentation of renal stones with SWL. The measurement of infundibulopelvic angle in different manner helps to predict the stone-free status in patients with renal calculi located not only in lower pole, but also in renal pelvis and upper or middle pole. Gravity effect is not enough to justify the significant influence of the radiographic anatomic features on the stone clearance and fragments retention after SWL.

Management of Clinically Insignificant Residual Fragments following Shock Wave Lithotripsy

Clinically insignificant residual fragments (CIRFs) are small fragments (less than 5 mm) that are present in upper urinary tract at the time of regular post-SWL followup. The term is controversial because they may remain silent and asymptomatic or become a risk factor for stone growth and recurrence, leading to symptomatic events, and need further urologic treatment. Although a stone-free state is the desired outcome of surgical treatment of urolithiasis, the authors believe that the presence of noninfected, nonobstructive, asymptomatic residual fragments can be managed metabolically in order to prevent stone growth and recurrence. Further urologic intervention is warranted if clinical indications for stone removal are present.

[Controversy on lower pole stones: monitor or intervene?]

For many years, the treatment options of lower pole stones have been discussed controversially: Watchful waiting, shock wave lithotripsy, flexible ureterorenoscopy and percutaneous litholapaxy. Small lower pole stones <1 cm can be monitored actively. Shock waves can disintegrate the stones and are recommended for stones <1 cm. However, the stone-free rate is limited because of the particular anatomy of the lower pole. Modern flexible ureterorenoscopes can nowadays reach even anatomically unfavourable lower calyxes. For stones <1 cm good stone-free results can be achieved. For larger stones >2 cm percutaneous nephrolithotomy (PNL) is the standard treatment modality.

Which is more important in predicting the outcome of extracorporeal shockwave lithotripsy of solitary renal stones: stone location or stone burden?

PURPOSE

To assess the effect of stone location and burden on the outcome of extracorporeal shockwave lithotripsy (SWL) as a primary treatment of solitary renal stone.

PATIENTS AND METHODS

The study included 438 patients with a solitary renal stone who underwent SWL as a primary treatment for their stones. All were evaluated by plain radiography of the kidneys, ureters, and bladder (KUB), ultrasonography, intravenous urography, or noncontrast enhanced CT before SWL and followed up for 3 months after treatment by KUB radiography and/or ultrasonography. Patients were classified into four groups according to stone location (renal pelvis, lower, middle, and upper calix) and three groups according to stone burden (≤ 1 cm(2), 1.1-2 cm(2), and >2 cm(2)). Treatment outcome was considered successful if no residual fragments (stone free) or clinically insignificant nonobstructing residuals less than 4 mm remained after 3 months of follow-up.

RESULTS

The mean age of the patients was 45.1 ± 12.5 years. The mean stone burden, number of sessions, and shockwaves for the whole study were 1.3 ± 0.49 cm(2), 2.1 ± 0.7 sessions, and 5616.6 ± 2017.4 shockwaves, respectively. The stone-free rate of the study was 65.1%. The stone-free rates of the stones in the renal pelvis, lower, middle, and upper calices were 72.4%, 56%, 55.6%, and 69%, respectively. The stone-free rate of the stones ≤ 1 cm(2), 1.1 to 2 cm(2), and >2 cm(2) was 50.2%, 39.6%, and 10.2%, respectively (P<0.05).

CONCLUSION

Stone burden rather than stone location is considered as a predicting factor for the outcome of SWL in a solitary renal stone, especially in the renal pelvis and lower calix.

A clinical nomogram to predict the successful shock wave lithotripsy of renal and ureteral calculi

PURPOSE

Although shock wave lithotripsy is dependent on patient and stone related factors, there are few reliable algorithms predictive of its success. In this study we develop a comprehensive nomogram to predict renal and ureteral stone shock wave lithotripsy outcomes.

MATERIALS AND METHODS

During a 5-year period data from patients treated at our lithotripsy unit were reviewed. Analysis was restricted to patients with a solitary renal or ureteral calculus 20 mm or less. Demographic, stone, patient, treatment and 3-month followup data were collected from a prospective database. All patients were treated using the Philips Lithotron® lithotripter.

RESULTS

A total of 422 patients (69.7% male) were analyzed. Mean stone size was 52.3±39.3 mm2 for ureteral stones and 78.9±77.3 mm2 for renal stones, with 95 (43.6%) of the renal stones located in the lower pole. The single treatment success rates for ureteral and renal stones were 60.3% and 70.2%, respectively. On univariate analysis predictors of shock wave lithotripsy success, regardless of stone location, were age (p=0.01), body mass index (p=0.01), stone size (p<0.01), mean stone density (p<0.01) and skin to stone distance (p<0.01). By multivariate logistic regression for renal calculi, age, stone area and skin to stone distance were significant predictors with an AUC of 0.75. For ureteral calculi predictive factors included body mass index and stone size (AUC 0.70).

CONCLUSIONS

Patient and stone parameters have been identified to create a nomogram that predicts shock wave lithotripsy outcomes using the Lithotron lithotripter, which can facilitate optimal treatment based decisions and provide patients with more accurate single treatment success rates for shock wave lithotripsy tailored to patient specific situations.

Prognostic variables for shockwave lithotripsy (SWL) treatment success: no impact of body mass index (BMI) using a third generation lithotripter

OBJECTIVE

• To investigate the effect of different variables including body mass index (BMI) on therapy outcome in patients with upper urinary tract stones treated with a third generation lithotripter, as BMI has been reported to be an independent predictor for stone-free status after extracorporeal shockwave lithotripsy (SWL) performed with first or second generation lithotripters.

PATIENTS AND METHODS

• In all, 172 patients with kidney stones with a mean (range) size of 9.2 (3.0-32.0) mm were included in the study. • In all, 91 patients (52.9%) were treated with a ureteric stent in situ. • For SWL therapy a third generation, electromagnetic lithotripter (Siemens Lithoskop™) was used. Stone-free status was reached, when no more treatable stones were present (no stone or stone < 3 mm). • BMI, stone size and localization, age, gender, treatment parameters and ureteric stent in situ were evaluated for their prognostic relevance on therapy success.

RESULTS

• The mean (range) BMI of all patients was 27.8 (19.0-58.6) kg/m(2). • Patients were categorized into two groups: A) patients that were stone free after one treatment; B) patients with residual stones. The mean (sd) BMI was 27.4 (4.6) kg/m(2) and 28.4 (6.1) kg/m(2) for A and B, respectively. • Univariate and multivariate analysis for freedom of stones showed that only stone size (P < 0.01) and presence of a ureteric stent (P = 0.01) were independent prognostic variables. • BMI had no significant influence on therapy outcome (P = 0.51).

CONCLUSIONS

• Using a third generation lithotripter, BMI was not an independent predictor of stone-free rate after SWL therapy of kidney stones. • This effect might be attributed to a greater penetration depth of the shockwave energy. Stone size and a ureteric stent in situ were the only variables with prognostic significance.

Management options for lower pole renal calculi

PURPOSE OF REVIEW

The optimal treatment of lower pole renal calculi is controversial. Shock wave lithotripsy, ureteroscopy and percutaneous nephrostolithotomy all constitute viable therapeutic options in select patients.

RECENT FINDINGS

Lower pole stones smaller than 1 cm in diameter can be managed with observation, shock wave lithotripsy or ureteroscopy. Patients electing expectant management should be counseled regarding the potential for stone-related symptom progression and need for future intervention. Shock wave lithotripsy and ureteroscopy have similar stone-free rates, although shock wave lithotripsy may be preferable due to more favorable secondary outcomes. Lower pole stones 1-2 cm in diameter are best managed with percutaneous nephrostolithotomy, although ureteroscopy is an option in select patients, particularly those not considered candidates for percutaneous nephrostolithotomy. Finally, patients with lower pole stones larger than 2 cm are best served with percutaneous nephrostolithotomy, as the morbidity in experienced hands is low and stone-free rates are unequivocally higher than those of other treatment modalities.

SUMMARY

A variety of factors, including patient body habitus, local renal anatomy, cost and patient preference, must be taken into consideration when determining the optimal treatment modality for lower pole renal calculi.

Pre- and perioperative predictors of short-term clinical outcomes in patients undergoing percutaneous nephrolitholapaxy

Percutaneous nephrolitholapaxy (PCNL) with modern stone disintegration technologies is the treatment of choice for patients with extensive stone burden or stones refractory to extracorporeal shock wave lithotripsy. However, little is known about factors predicting unfavourable outcome in terms of perioperative complications, residual stone burden or prolonged hospitalization. The aim of this study was to evaluate preoperative, patient- and stone-related parameters that might influence the perioperative course and short-term clinical outcomes. In a prospective study, age, sex, body mass index (BMI), bidimensional size, side, pre-existent urinary tract infection, pre-existent hydronephrosis and previous kidney surgery were used as independent variables in both univariate and multiple regression models in 109 PCNL patients in order to predict the partition of patients rendered stone free at hospital discharge, duration of surgery, length of inpatient hospital stay and the occurrence of major complications. Univariate and multiple regression analysis revealed that stone size was the only factor influencing duration of surgery (P < 0.001) and hospitalization (P = 0.02), but had no predictive potential for major complications. Univariate analysis showed a trend towards longer inpatient hospital stay and clinically relevant residuals in patients with lower BMI (P = 0.05 and 0.06); however, after controlling for the other confounding variables, this was only reproducible for residual stone burden. The other patient- and stone-related factors did not adversely affect the outcome measures. In our patient sample treated with PCNL by LithoClast Master/Ultra we found evidence that large stone burden is a prognostic factor predicting longer surgery and prolonged hospitalization. In addition, patients with lower BMIs might be at higher risk of not being stone free at hospital discharge accompanied by prolonged inpatient treatment.

The repeated extracorporeal shock waves and the renal parenchyma injury on normal and diabetic rats

PURPOSE

To assess the effect of repeated extracorporeal shock waves (ESW) on renal parenchyma of normal and diabetic rats.

METHODS

40 normal rats (A) and 40 diabetic rats (B) were assigned for ESW (Direx Tripter X1 - 14 KVA) as follow: A1/B1 and A3/B3 no ESW; A2/B2 one ESW (2,000 SW); A4/B4 two ESW (4,000 SW) in an elapsed 14 days. All the animals were sacrificed 3 days after the ESW and samples of renal parenchyma were histological prepared, stained by H&E. For each animal the frequency of hemorrhage focus (HF) in the subcapsular, interstitial and glomerulus area was calculated (percentage) on 20 randomly histological sections.

RESULTS

No one HF was identified in all normal or diabetic animals without ESW (A1, A3 and B1, B3). In the normal rats the HF frequency was similar to one ESW (subcapsular =15%; interstitial =20% and glomerular =10%) or repeated ESW (subcapsular =25%; interstitial =20%; glomerular=10%). In diabetic rats the occurrence of HF with repeated ESW was more frequent (subcapsular =40%; interstitial =30% and glomerular =10%) than with a single ESW (subcapsular =25%; interstitial =15% and glomerular =15%).

CONCLUSION

A single ESW or a repeated ESW caused a mild and similar damage on renal cortex of normal rats. In diabetic rats the repeated ESW may result in an accumulated damage, especially with focus of hemorrhage in subcapsular and interstitial tissue and glomerulus edema.

Limitations of extracorporeal shock wave lithotripsy

PURPOSE OF REVIEW

Extracorporeal shock wave lithotripsy (ESWL) is the preferred modality for the treatment of renal and upper ureteric calculi. The present review focuses on the limitations of ESWL, where recent developments have tried to identify patients who are unlikely to succeed with ESWL and where improvements in shock wave delivery may increase successful stone fragmentation.

RECENT FINDINGS

Evaluation of patients prior to ESWL is especially important, and the use of imaging in the decision process, with the use of computed tomography attenuation values and skin-to-stone distance, can help improve our ability to identify suitable patients for shock wave treatment. Continued research into the methods of shock wave delivery techniques and lithotripter designs will help achieve better stone fragmentation rates with reduced side effects.

SUMMARY

The importance of traditional factors in predicting ESWL success, such as stone size, location, composition and renal anatomy, are well known. More recently, authors have created nomograms to predict stone-free outcome after ESWL. Others have used the information obtained from computed tomography to predict stone comminution. In addition, modifications in shock wave delivery by altering shock rate and voltage have been researched in an effort to improve shock wave efficacy.