Efficacy of Extracorporeal Shockwave Lithotripsy with Patients Rotated Supine or Rotated Prone for Treating Ureteral Stones: A Case-Control Study

The transgluteal approach to shockwave lithotripsy to treat distal ureter stones: a prospective, randomized, and multicenter study

PURPOSE

We compared the outcomes of SWL to treat distal ureter stones with regard to the conventional prone and supine positions using the transgluteal approach through the greater sciatic foramen.

METHODS

A prospective, randomized, single-blind, and multicenter study was conducted between October 2014 and July 2015. The inclusion criteria were radio-opaque distal ureter stones with a maximum diameter of 0.5-2 cm as measured on a CT scan. The included 160 patients were randomly assigned to two groups: the prone group (n = 80; treated in the conventional prone position) and the transgluteal group (n = 80; treated in the supine position using a transgluteal approach). In the latter group, the focused shock wave was transmitted through the greater sciatic foramen with the head positioned at a 40° angle to the vertical. "Stone-free" was defined as the complete clearance of stone fragments, assessed using a CT scan at 2 weeks after treatment. Overall satisfaction was self-reported using a 0-5 Likert scale.

RESULTS

The overall efficacy was 66.9%. The stone-free rate was significantly higher in the transgluteal group (72.6%) than in the prone group (54.7%; odds ratio 2.413, 95% CI 1.010-5.761, P = 0.023). No serious adverse events due to treatment were observed in either group. The satisfaction score of the transgluteal group was 4.21 ± 0.81, and 83.6% were willing to repeat the same procedure if necessary.

CONCLUSIONS

SWL using the transgluteal approach via a supine position through the greater sciatic foramen was more effective than via the conventional prone position. Furthermore, this approach provided a comparably safe and satisfactory procedure.

Assessing the Magnitude of Effect of Bone Structures on Shockwave Lithotripsy Fragmentation: Results from an In Vitro Study

INTRODUCTION

Several anatomic and clinical factors have been implicated in the failure rates of shock wave lithotripsy (SWL), including the attenuating effects of bony structures. We designed an in vitro model that incorporates the lumbar spine, including vertebral bodies and transverse processes along the pathway of shockwaves, to mimic the clinical scenario during SWL of upper ureteral stones. We hypothesized that the presence of bone structures in the SWL pathway significantly affects the fragmentation rate.

MATERIALS AND METHODS

An ordnance gelatin (OG) model was conceptualized and created to allow a pig's lumbar spine to be embedded within it. Artificial urinary calculi weighing 2 ± 0.1 g (1.2-cm diameter) were prepared using BegoStone plaster. The trial was divided into two arms: group 1 models had OG only and served as the control and group 2 models had the bone embedded in the gelatin with stone wells placed above the transverse processes. Twenty-four stones per group were subjected to SWL using the STORZ MODULITH SLX-F2 lithotripter, using the same treatment parameters. Fragments were sieved through 2- and 4-mm filters, and the fragmentation coefficients (FC) were calculated. The Mann-Whitney test was used to compare FC between the two groups.

RESULTS

The mean fragmentation rate of group 1 was statistically significantly higher compared with group 2 using a 4-mm sieve (43% vs 0.62%, p < 0.001) and the 2-mm filter (18% vs 0.52%, p < 0.001).

CONCLUSIONS

The presence of bone structures dramatically reduces the fragmentation rate of phantom stones using an OG in vitro model. The OG model is inexpensive and simple to use to simulate clinical situations during SWL.

Impact of official technical training for urologists on the efficacy of shock wave lithotripsy

To evaluate the efficacy of company-initiated training of urologists on shock wave lithotripsy (SWL) treatment results, we retrospectively assessed 602 patients who underwent SWL in Nagoya City University Hospital between January 2004 and June 2011 using Lithotripter S (Dornier MedTech, Japan). Training-provided by a training specialist of the company in June 2010-focused on the targeting of renal and proximal ureter stones with a combination of radiography and ultrasonography (US). The stretcher wedges were positioned in the semi-prone position or the semi-supine position for middle and distal ureter stones, respectively. Success rates between 519 pre-training treatments and 83 post-training treatments were compared. Patient age and stone location, burden, number, and composition did not significantly differ between pre- and post-training. Training improved the overall success rate from 66.3 to 87.2 % (P < 0.0001). The mean number of SWL treatments decreased from 1.8 ± 1.8 to 1.4 ± 1.3 (P = 0.01). The first SWL treatment success rate increased from 67.1 to 83.7 % (P = 0.002), and the need for multiple treatments decreased. The frequency of detection of renal and proximal ureter stones by both radiography and US increased from 10.5 % before training to 58.2 % after training (P < 0.0001). Significant factors for successful SWL were determined to be training and prone position for distal ureter stones by multivariate analysis and ultrasonic detection for renal and proximal ureter stones by univariate analysis. Skills in targeting stones using ultrasonography and selecting the proper therapeutic position are essential for improving the success rate of stone removal.

Adjuncts to improve outcomes of shock wave lithotripsy

Shock wave lithotripsy (SWL) has been a major tool in the treatment of urinary stones for nearly three decades. In recent years, SWL technology has been less effective at fragmenting stones than earlier devices; thus, adjunctive maneuvers to improve stone-free rates after SWL have been required. This article summarizes several of these adjuncts, such as slower shock wave rate, the use of percussion therapy to clear fragments, medications to hasten expulsion of fragments, and appropriate selection and positioning of patients for SWL.

SWL is More Cost-Effective than Ureteroscopy and Holmium:YAG Laser Lithotripsy for Ureteric Stones: A Comparative Analysis for a Tertiary Referral Centre

Background:

To identify the most cost-effective treatment for ureteric stones ≤15 mm in our department, by using an economic model to compare the total cost of shockwave lithotripsy (SWL) versus ureteroscopy with Holmium:YAG laser lithotripsy (URSL).

Patients and methods:

Data for patients treated with the same lithotriptor were retrospectively analyzed. The financial department provided data about the cost of procedures. This model accepted a 100% stone-free rate for URSL in outpatients, and a 50% rate of insertion of a ureteric stent. The cost for each procedure to render a patient stone-free was estimated by the following equations: costSWL = cost(initial SWL session) + [cost(SWL session) × retreatment rate] + [cost(URSL) × SWL failure rate] + [cost(stent insertion and removal) × rate] + [cost(KUB film) × 4] costURSL = cost(URSL) + [cost(stent removal) × 50%] + [cost(KUB film) × 2]

Results:

Records of 228 patients with previously untreated solitary radiopaque ureteric stones ≤15 mm were reviewed. The total cost for SWL (cSWL) was £1491/patient, while the total cost for URSL (cURSL) was £2195/patient. The difference was highest in the upper ureter (over £1000), and lowest in the distal part (URSL about 40% more expensive). For lower ureteric stones >10 mm, SWL was over £500 more expensive than URSL.

Conclusion:

Using data from the department to calculate cost-effectiveness for ureteric stones ≤15 mm a difference in favour of SWL versus URSL was found. Uniform guidelines incorporating cost are impossible considering differences between countries; each centre should probably assess their data individually.

Optimizing Shock Wave Lithotripsy in the 21st Century

OBJECTIVE

Shock wave lithotripsy (SWL) has radically changed treatment of stone disease and appears to be the first option for the majority of patients. This review of current literature focused on suggestions for optimising technique, patient selection, results, and lithotriptor comparison for SWL.

METHODS

Literature search for SWL was performed for recently published papers in English language. Topics of interest were treatment protocols; patient evaluation; pre-SWL prediction of outcome; lithotriptor technology; efficacy; and methods to assess the effects, decrease complications, and compare lithotriptors. Earlier classic papers on SWL and guidelines for stone disease were also reviewed.

RESULTS

Recent literature contained important recommendations about SWL concerning (1) methods to predict stone fragmentation; (2) identification of factors contributing to treatment failure for lower pole and ureteric calculi; (3) guidelines from urological associations; (4) manoeuvres and changes in SWL delivery (slower rate, twin-pulse technique) to increase efficacy and decrease complications; (5) clarification of the role of medical treatment (antibiotics, alpha-blockers); (6) role of SWL in calyceal stones, CIRF, and abnormal kidneys; (7) obesity and SWL; and (8) methods to evaluate and compare lithotriptors.

CONCLUSIONS

SWL delivered in an outpatient setting as an anaesthesia-free treatment is still considered the first option for the majority of stones with a minimal number of complications. Better understanding of the physics of shockwave delivery is required, together with treatment optimisation by limiting renal damage and better selection of patients because this approach will offer maximum benefit to patients and physicians, as well as more cost-effective treatment.