Redefining the Limits of Flexible Ureterorenoscopy

Abstract

Clearance rates of >90% can be achieved for stones up to 20 mm with flexible ureterorenoscopy and holmium laser lithotripsy, but with larger stones, the stone-free rates reduce significantly. Therefore, 20 mm should be regarded as the upper limit of stone size that can be cleared in a single procedure. Stone density and location do not influence outcome.

The S.T.O.N.E. Score: A new assessment tool to predict stone free rates in ureteroscopy from pre-operative radiological features

“…The general consensus in the literature cites a negative correlation between stone size and SFR and is included in the S.T.O.N.E. Score (5,6).…”

“…Stone location is an important factor in the success of URS, especially lower pole stones (5,6,18). Although visualization of these stones may be possible with flexible endoscopes, the acute pelvic infundibular angle may prevent access to the stone, especially with less deflection of the ureteroscope when the basket or laser fiber is inside of the working channel.…”

“…Although visualization of these stones may be possible with flexible endoscopes, the acute pelvic infundibular angle may prevent access to the stone, especially with less deflection of the ureteroscope when the basket or laser fiber is inside of the working channel. Generally, SFR for lower pole stones have typically been reported around 80% (5,6,18). Other intra-renal and proximal ureteral stones have been reported with a stone free rate of approximately 90% (18).…”

“…This trend has been observed in URS but without statistical significance. A study found that stones successfully treated by URS had a mean of 858 HU while stones that were unsuccessfully treated had a mean of 1115 HU (6). Stone composition increasing density and hardness may prolong OR time.…”

“…Modern stone therapy should ensure high effectiveness combined with low complication rate. URS has become common in the treatment of proximal and intrarenal stones < 20mm as a result of technological improvements in visualization and laser technology (5,6).…”