Ureteric stents compromise stone clearance after shockwave lithotripsy for ureteric stones: results of a matched-pair analysis

Shock Wave Lithotripsy Outcomes for Upper and Lower Ureteral Stones in Non-obese and Non-Pre-stented Adults: Is One Session Sufficient?

Purpose

This study aims to evaluate differences in shock wave lithotripsy (SWL) outcomes between upper and lower ureteral stones and identify patients who are likely to have a stone-free status after one session of SWL.

Materials and methods

After approval from the institutional review board and from a prospectively maintained database of 628 patients, 182 were retrospectively identified, who have had SWL for a single lower or upper ureteral stone and met the inclusion criteria. Age, body mass index (BMI), and stone size were similar among the groups. This study included non-pre-stented patients with solitary lower or upper ureteral radiopaque stones identified on non-contrast-enhanced computed tomography (NCCT), did not have acute obstruction, and had either normal body mass index (BMI) or overweight status. Patients were treated with Sonolith i-sys electroconductive lithotripter (focal length: 21 cm) (EDAP TMS, Vaulx‐en‐Velin, France). Success was defined as the absence of residual of any size or a residual of ≤2 mm on NCCT after one month, whereas failure was having fragments >2 mm or requiring surgical intervention. Post-SWL assessments were completed one week after every session with an X-ray of the kidney-ureter-bladder (KUB-XR) and NCCT after one month.

Results

The upper and lower ureteral stone-free rates (SFRs) were 95% and 64.7%, respectively. Of them, 65% and 45%, respectively, were stone-free after one session. The cohort having a stone-free status after one SWL session was similar in age, sex, BMI, and stone density. The upper ureteral stone arm has a significant chance for one SFR session with a larger stone size, shocks per session, and maximum power delivered. In the receiver operating characteristic (ROC) curves, the optimal cut point number of sessions of 1.5, mean stone density (MSD) of 895, and stone size of 10.5 mm are the most likely to have successful SWL in the ureter.

Conclusion

For patients having ureteral stones with favorable factors, SWL modality is effective and safe. Moreover, SWL can be done for one or two sessions only with the presence of favorable factors.

Efficacy of supine trans-abdominal pronated shock head ESWL for treatment of distal ureteric stones: A pilot study

OBJECTIVE

To evaluate the efficacy of extracorporeal shockwave lithotripsy (ESWL) in supine trans-abdominal approach for distal ureteric calculi and to determine the variables that could affect the outcome results.

MATERIALS AND METHODS

Between November 2019 and January 2021, 172 patients with a solitary distal ureteric calculus were treated with ESWL in supine position with a pronated shock wave head against the anterior abdominal wall. The outcome of treatment evaluated and the clinical and radiological findings, as well as stone characteristics, were reviewed and correlated with the stone-free rate (SFR).

RESULTS

Overall SFR was 84.84% (140/165). Those with stone clearance, 83.57% (117/140) cleared after one session and 16.42% (23/140) needed more than one session. Only three factors had a significant impact on SFR, that is stone length, stone width, stone attenuation. For stone length ⩽ 9 mm SFR was 93.44% (114/122) compared to 60.46% (26/43) for stone length of 10-12 mm (p < 0.00001). There were statistically significant increased SFR for stones with attenuation of <0.0001 and for the mean stone width of 8.02 mm (p < 0.00001). Stone localisation was easy with good patient comfort.

CONCLUSION

Supine trans-abdominal ESWL is a new, effective and safe form of treatment for distal ureteric calculi. The stone length, stone width along with stone attenuation were the only significant predictors of stone free status in supine position.

A model to guide patient selection when managing ureteric stones with shockwave lithotripsy

Introduction:

The aim of this study was to create a model based upon significant prognostic factors to guide patient selection for shockwave lithotripsy.

Patients and methods:

We identified 150 patients attending for shockwave lithotripsy for ureteric stones between October 2010–February 2016. Data was collected retrospectively from electronic case notes and radiological images. All patients were treated with an on-site Storz Modulith SLX-F2 lithotripter. A model was created using computer software ‘R’.

Results:

One hundred and thirty-three patients were treated and 66% of those were deemed radiologically stone-free with shockwave lithotripsy. Four factors were found to be independently statistically significant with regards to stone-free status; age ( p=0.003), Hounsfield units ( p=0.002), prior nephrostomy insertion ( p=0.022) or prior stent insertion ( p=0.002). Our resulting model is:[Formula: see text]

Discussion and conclusions:

Our shockwave lithotripsy success would likely increase with improved patient selection. Age appears to be a novel significant factor in stone passage. This is an interesting observation worthy of further study given ageing populations in the developed world. The model will require further validation in order to confirm our findings, however the results have proven very encouraging.

Level of evidence:

2c

Indications and contraindications for shock wave lithotripsy and how to improve outcomes

For over 35 years shock wave lithotripsy has proven to be an effective, safe and truly minimally invasive option for the treatment of nephrolithiasis. Various technical factors as well as patient selection can impact the success of the procedure. We used published work focusing on outcomes of shock wave lithotripsy, risk of complications, and strategies for improving stone fragmentation to create this review. Multiple patient and technical factors have been found to impact success of treatment. Skin to stone distance, stone density and composition, size and location of the stone within the urinary system all influence stone free rates. A slower rate with a gradual increasing voltage, precise targeting, proper coupling will improve stone fragmentation and decrease risk of complications. The selection of appropriate patients through a shared decision making process and attention to the technical factors that improve stone free rates is key to providing an effective treatment and patient satisfaction.

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.

Has the pelvic renal stone position inside the upper loop of JJ stent any influence on the extracorporeal shock wave lithotripsy results?

Background

JJ stents are often encountered in patients with pelvic renal stones referred for shock wave lithotripsy, most of them being placed either for obstructive renal pelvic stones or for ureteric stones mobilized retrograde during the JJ stent insertion. The aim of the study was to determine whether the relative stone position in the upper loop of the JJ stent during extracorporeal shock wave lithotripsy (SWL) influences the efficiency of the procedure. The study was designed as a prospective cohort study on 162 patients addressing the same urological department, with single renal pelvic stone (primary or mobilized to the renal pelvis during the insertion of JJ stent), smaller than 15 mm, with JJ stent, treated by SWL using a second generation spark gap lithotripter, 18 kV, 3000 waves/session. Patients were divided in three groups according to the relative position of the stone to the upper loop of the JJ stent as appears on plain X-ray: stone-inside-loop, loop-crossing-stone and stone-outside the loop. The SWL success rate was the primary outcome of the study. p Value, Chi square and Kruskal–Wallis tests were used for statistical analysis.

Results

For stone-inside-loop cases, SWL efficiency was 22.7 versus 42 % for all the other cases (p = 0.002). Other factors for decreased SWL success rate were: higher stone radio-opacity, larger JJ of stent and obese patients. Study limitation is represented by the relative small study group and by the evaluation of stone density using plain X-ray instead of computer tomography.

Conclusions

For pelvic renal stones having the same density characteristics studied by plain X-ray, the SWL efficiency is lower in stone-inside-loop cases comparing with the other positions. The overall stone free rate for renal pelvic stones could be explained by the second generation lithotripter used for all procedures.

CUA Guideline: Management of ureteral calculi

The focus of this guideline is the management of ureteral stones. Specifically, the topics covered include: conservative management, medical expulsive therapy, active intervention with either shockwave lithotripsy (SWL) or ureteroscopy (URS), factors affecting SWL treatment success, optimizing success, and special considerations (e.g., pregnancy, urinary diversion). By performing extensive literature reviews for each topic evaluated, we have generated an evidence-based consensus on the management of ureteral stones. The objective of this guideline is to help standardize the treatment of ureteral stones to optimize treatment outcomes.

Supine versus Prone Position during Extracorporeal Shockwave Lithotripsy for Treating Distal Ureteral Calculi: A Systematic Review and Meta-Analysis

PURPOSE

We aimed at evaluating the efficacy of extracorporeal shockwave lithotripsy (SWL) for treating distal ureteral calculi performed in supine vs. prone position.

MATERIALS AND METHODS

Eligible studies were identified by 2 reviewers using PubMed, Embase, and Web of Science databases. Outcomes included stone-free rate after the first and the final SWL session, the mean number of shocks per SWL session, the mean percentage of power used in the first SWL session, and the mean number of SWL sessions per patient.

RESULTS

Pooled data among the 647 included patients showed that supine SWL was associated with a significantly higher stone-free rate than prone SWL. This difference was consistent for both the first SWL session (OR 4.17; 95% CI 2.53-6.87; p < 0.00001) and the final session (OR 3.02; 95% CI 1.96-4.67; p < 0.00001). No differences in the mean number of shocks per SWL session, the mean percentage of power used in the first SWL session, and the mean number of SWL sessions per patient were observed between the positions. SWL complications were infrequent and the incidence was insufficient for further analysis.

CONCLUSION

SWL is safe and effective for the management of distal ureteral calculi, and supine SWL is more effective than prone SWL for achieving a stone-free status.

Is shock wave lithotripsy efficient for the elderly stone formers? Results of a matched-pair analysis

The aim of the study was to evaluate the impact of age on the efficacy of extracorporeal shock wave lithotripsy (SWL), in a comparative study based on the principles of matched-pair analysis. Over a period of 4 years, 2,311 patients were treated with SWL in a tertiary referral center. Patient and stone data were recorded in a prospective electronic database. Among these patients, 115 (4.97%) were older than 70 years of age and fulfilled the criteria for inclusion in the study (Group A). For the purposes of the comparative analysis, Group A patients were matched for gender and stone parameters (side, location of stone, and diameter ±2 mm) with a control group of patients under the age of 70 (Group B). Following matching, the patients' electronic medical records were reviewed, to identify SWL success rates at 3 months and McNemar's test was used to compare the efficacy of SWL between the two groups. Matching was possible in all cases. The results indicate that there were no statistically significant differences in the mean number of SWL sessions or in the mean number of impulses per session between the two groups. The overall stone clearance rate achieved by SWL alone was 71.3% for Group A and 73.9% for group B. Discordant pairs were found in 37 cases (in 17 pairs only patients in Group A became stone-free, while in 20 pairs only patients in Group B became stone-free). By using McNemar's test, the difference in stone clearance rates between the two groups was not found to be statistically significant (p = 0.742). A total of 22 patients (19.1%) in Group A and 17 patients (14.7%) in Group B underwent an adjuvant procedure to achieve stone clearance. McNemar's test also revealed the absence of any statistically significant difference in SWL success rates between older and younger patients in the subgroups of patients presenting with either ureteric or renal stones (p = 0.727 and p = 0.571, respectively). In conclusion, SWL is still considered one of the first-line tools for geriatric patients suffering from urolithiasis, as increased age alone does not seem to adversely affect the efficacy of SWL.

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.

Evaluation of outcome following lithotripsy

PURPOSE OF REVIEW

Shockwave lithotripsy (SWL) is considered as an initial option for a significant proportion of urinary tract stones. Despite efforts for standardized terminology and methodology, published studies on lithotripsy outcome are very different. This review will focus on a brief description of evidence-based medicine and recent literature results on SWL outcome.

RECENT FINDINGS

The introduction of hierarchy in scientific evidence is becoming more widespread. Various grading systems have attempted to rank recommendations according to type and amount of evidence. Different levels of evidence have been created for therapy, diagnosis and prognosis. Various authors have developed scoring systems and identified radiographic parameters to predict SWL outcome. The long-term safety of lithotripsy on renal function has been demonstrated. Randomized controlled trials and meta-analysis have shown that medical expulsive therapy and a slower shockwave rate will improve SWL outcome.

SUMMARY

Evidence-based medicine is rapidly becoming an indispensable part of everyday medical practice. Common terminology is necessary for proper evaluation of SWL. Different types of studies are required to investigate efficacy, compare SWL to other options, complications and so on. Randomized clinical trials are of the highest value; matched-pair analyses and well designed controlled studies can offer significant help.