Flexible Ureterorenoscopy Versus Shockwave Lithotripsy for Kidney Stones ≤2 cm: A Randomized Controlled Trial

Technological innovations in shock wave lithotripsy

INTRODUCTION

Since 1980, extracorporeal shock wave lithotripsy (SWL) has been employed in the treatment of urolithiasis, offering noninvasive alternatives to surgical techniques. In addition to being limited by the size and location of the stones, its efficacy is influenced by several factors. Despite the advancement of other surgical techniques, SWL could maintain its position with new improvements. Our objective is to review the existing literature on the latest advances in the extracorporeal treatment of lithiasis.

MATERIAL AND METHODS

A non-systematic literature review was carried out from 2017 to 2023 to obtain 26 articles on three different emerging technologies in extracorporeal lithotripsy: Burst Wave Lithotripsy (BWL), Histotripsy, and Microbubble Lithotripsy (ML).

RESULTS

The BWL uses sinusoidal bursts of US waves delivered at lower and higher frequencies than conventional SWL. Its mechanism of action generates a higher quality fragmentation (fine fragments) instead of generating tensile stresses for stone fracture resulting in larger fragments, as in traditional SWL. Studies in pigs and humans have shown effective fragmentation with a good safety profile. Based on High Intensity Focused Ultrasound (HIFU) technology, histotripsy fragments tissue through cavitation. Good in vitro results have been shown, but the formation of microbubbles between the stone and ultrasound waves hinders the progress of this technique. Microbubble Lithotripsy (ML) combines microbubbles and ultrasound for safe and effective stone fragmentation. In vitro and pig results are promising. This technique can help optimize treatments and reduce energy levels.

CONCLUSIONS

Technological innovation is not only being applied to endourological techniques, but also to ESWL. New techniques such as BWL, histotripsy and ML are promising, with good results in the research phase.

Mechanism of urosepsis: relationship between intrarenal pressures and pyelovenous backflow

To document the histological changes observed in renal units subjected to elevated intrarenal pressures (IRPs) and postulate the possible mechanisms of infectious complications after ureteroscopy.

MATERIALS AND METHODS

Ex vivo studies were performed on porcine renal models. Each ureter was cannulated with a 10-F dual-lumen ureteric catheter. A pressure-sensing wire was inserted through one lumen and with the sensor positioned in the renal pelvis for IRP measurement. Undiluted India ink stain was irrigated through the second lumen. Each renal unit was subjected to ink irrigation at target IRPs of 5 (control), 30, 60, 90, 120, 150, and 200 mmHg. Three renal units were subjected to each target IRP. After irrigation, each renal unit was processed by a uropathologist. Macroscopically, the amount of renal cortex stained by ink was calculated as a percentage of the total perimeter. Microscopically, presence of ink reflux into collecting ducts or distal convoluted tubules, and pressure-related features, was noted at each IRP.

RESULTS

Signs of pressure, as represented by collecting duct dilatation, was first observed at 60 mmHg. Ink staining was consistently observed in the distal convoluted tubules at IRPs ≥60 mmHg, and all renal units above this pressure showed renal cortex involvement. At ≥90 mmHg, ink staining was observed in venous structures. At 200 mmHg, ink staining was observed in supportive tissue, venous tributaries in the sinus fat, peritubular capillaries, and glomerular capillaries.

CONCLUSION

Using an ex vivo porcine model, pyelovenous backflow occurred at IRPs of ≥90 mmHg. Pyelotubular backflow occurred when irrigation IRPs were ≥60 mmHg. These findings have implications for the development of complications after flexible intrarenal surgery.

Extracorporeal shock wave lithotripsy (ESWL) versus percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) for kidney stones

BACKGROUND

Nephrolithiasis is a common urological disease worldwide. Extracorporeal shock wave lithotripsy (ESWL) has been used for the treatment of renal stones since the 1980s, while retrograde intrarenal surgery (RIRS) and percutaneous nephrolithotomy (PCNL) are newer, more invasive treatment modalities that may have higher stone-free rates. The complications of RIRS and PCNL have decreased owing to improvement in surgical techniques and instruments. We re-evaluated the best evidence on this topic in an update of a Cochrane Review first published in 2014.

OBJECTIVES

To assess the effects of extracorporeal shock wave lithotripsy compared with percutaneous nephrolithotomy or retrograde intrarenal surgery for treating kidney stones.

SEARCH METHODS

We performed a comprehensive search in CENTRAL, MEDLINE, Embase, and ClinicalTrials.gov with no restrictions on language or publication status. The latest search date was 6 December 2022.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs that compared ESWL with PCNL or RIRS for kidney stone treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies, extracted data, and assessed risk of bias. Our primary outcomes were treatment success rate at three months (defined as residual fragments smaller than 4 mm, or as defined by the study authors), quality of life (QoL), and complications. Our secondary outcomes were retreatment rate, auxiliary procedures rate, and duration of hospital stay. We performed statistical analyses using a random-effects model and independently rated the certainty of evidence using the GRADE approach.

MAIN RESULTS

We included 31 trials involving 3361 participants (3060 participants completed follow-up). Four trials were only available as an abstract. Overall mean age was 46.6 years and overall mean stone size was 13.4 mm. Most participants (93.8%) had kidney stones measuring 20 mm or less, and 68.9% had lower pole stones. ESWL versus PCNL ESWL may have a lower three-month treatment success rate than PCNL (risk ratio [RR] 0.67, 95% confidence interval [CI] 0.57 to 0.79; I2 = 87%; 12 studies, 1303 participants; low-certainty evidence). This corresponds to 304 fewer participants per 1000 (397 fewer to 194 fewer) reporting treatment success with ESWL. ESWL may have little or no effect on QoL after treatment compared with PCNL (1 study, 78 participants; low-certainty evidence). ESWL probably leads to fewer complications than PCNL (RR 0.62, 95% CI 0.47 to 0.82; I2 = 18%; 13 studies, 1385 participants; moderate-certainty evidence). This corresponds to 82 fewer participants per 1000 (115 fewer to 39 fewer) having complications after ESWL. ESWL versus RIRS ESWL may have a lower three-month treatment success rate than RIRS (RR 0.85, 95% CI 0.78 to 0.93; I2 = 63%; 13 studies, 1349 participants; low-certainty evidence). This corresponds to 127 fewer participants per 1000 (186 fewer to 59 fewer) reporting treatment success with ESWL. We are very uncertain about QoL after treatment; the evidence is based on three studies (214 participants) that we were unable to pool. We are very uncertain about the difference in complication rates between ESWL and RIRS (RR 0.93, 95% CI 0.63 to 1.36; I2 = 32%; 13 studies, 1305 participants; very low-certainty evidence). This corresponds to nine fewer participants per 1000 (49 fewer to 48 more) having complications after ESWL.

AUTHORS' CONCLUSIONS

ESWL compared with PCNL may have lower three-month success rates, may have a similar effect on QoL, and probably leads to fewer complications. ESWL compared with RIRS may have lower three-month success rates, but the evidence on QoL outcomes and complication rates is very uncertain. These findings should provide valuable information to aid shared decision-making between clinicians and people with kidney stones who are undecided about these three options.