Introduction
The most desirable conditions following a successful retrograde intrarenal surgery (RIRS) procedure are a complete flush-out of all stone fragments and diminish stone related events (SRE)1,2. One of the primary metrics used to measure the outcome of RIRS is the stone-free rate (SFR). Residual stone fragments (RSF) of 4 mm or less after RIRS are accepted as clinically insignificant 3. RIRS studies have shown that in almost 20% of cases, clinically insignificant RSFs are observed postoperatively 4; however, these RSF may grow and cause stone-related events (SRE) such as pain and infection5,6.
RSFs were detected by ultrasonography (USG), kidneys, ureters, bladder (KUB) radiography, or computed tomography (CT) 7. The most accurate imaging technique is the CT scan, which may show stones as small as 1 mm, although concerns about radiation exposure limit its use8. Also, for economic reasons, CT is underutilized for imaging RSFs; therefore, a wide range of SFRs are reported following RIRS 9-12.
Various techniques and methods have been reported in the literature to achieve an utterly stone-free status and to reduce radiation exposure, including artificial intelligence algorithms 13,14. This study investigates the effectiveness of second-look flexible ureterorenoscopy (URS) to achieve a true stone-free status and decrease stone-related events. To the best of our knowledge, the use of routine second-look flexible URS for this purpose has not been studied previously.