Clinical Scorecard: An Innovative System for Small Fragment Removal Shows Potential to Enhance Stone Extraction in Lithotripsy

At a Glance

Key Highlights

• Residual stone fragments post-surgery are associated with high rates of clinical intervention and disease progression, challenging the notion of 'clinically insignificant' fragments.
• The SFRS integrates a Syphon Ureteric Access Sheath, Dual Action Pump, and steerable Agitator catheter to facilitate removal of small stone fragments during and immediately after lithotripsy.
• Initial clinical trial phases focus on safety (intra-renal pressure <40 mm Hg) and efficacy (aiming to remove >75% of stone fragments) with promising early results.

Guideline-Based Recommendations

Diagnosis

• Use flexible ureteroscopy with retrograde pyelogram and intra-renal pressure monitoring during stone removal procedures.

Management

• Employ high frequency laser vaporisation with low energy settings to fragment stones into dust and small fragments.
• Utilize the SFRS system to actively remove small stone fragments intraoperatively to reduce residual fragments.

Monitoring & Follow-up

• Measure intra-renal pressure continuously to ensure it remains below 40 mm Hg during procedures.
• Monitor irrigant flow rates and stone fragment clearance intraoperatively.

Risks

• Residual stone fragments, even <4 mm, carry significant risk of clinical stone episodes and disease progression.
• Elevated intra-renal pressure during irrigation may pose safety concerns.

Patient & Prescribing Data

Adults with proximal ureter or renal collecting system stones undergoing flexible ureteroscopy and laser lithotripsy

Pre-stenting and use of SFRS components facilitate effective stone fragment removal with minimal learning curve for surgeons.

Clinical Best Practices

• Pre-stent patients prior to flexible ureteroscopy and lithotripsy to facilitate access.
• Use dual guidewires including a safety wire for ureteric access sheath placement.
• Position irrigation bag 140 cm above kidney level for optimal flow.
• Employ fluoroscopic guidance to steer the Agitator catheter for targeted fragment mobilization.
• Continuously monitor intra-renal pressure and irrigant flow during procedures to ensure safety.

References

• Cochrane meta-analysis on natural history of fragments post-stone surgery
• Commentary on clinical significance of residual stone fragments
• Kang et al. study on fate of dust fragments post-lithotripsy
• Initial in vitro evaluation of SFRS device
• Description of Syphon Ureteric Access Sheath by Lazarus
• Description of Syphon Ureteric Access Sheath by Yekani