Presentation Authors: Alim Dymov*, Leonid Rapoport, Dmitry Enikeev, Dmitry Tsarichenko, Nikolay Sorokin, Gagik Akopyan, Alexandra Proskura, Stanislav Ali, Roman Klimov, Vladimir Lekarev, Dmitry Korolev, Moscow, Russian Federation
Introduction: Stone Free rate is routinely used to assess the efficiency of surgical treatment for kidney stones. However, there is an inconsistency in the definition of 'stone-free' due to differences in the timing of the assessment and the size and location of stone fragments. It is widely accepted to perform CT scanning on postoperative day (POD) 1 to evaluate residual stones after PCNL. But this timing may not be optimal for SFR assessment after RIRS since dust accumulations can mimic real residual fragments at short-term follow-ups. This study evaluates the SFR on POD 3 and POD 90 after RIRS. We defined â€œStone-freeâ€ as absence of any stone fragments after surgery.
Methods: 32 patients who underwent RIRS for renal stones between January, 2018 and July, 2018 were enrolled into the study. Stone size ranged 7 â€“ 25 mm (medium size - 11,4 mm) and stone density varied from 330 to 1960 HU (mean density 987 HU). SuperPulse Thulium fiber laser (IRE Polus, Russia) was used for stone disintegration with different settings in dusting and fragmentation modes (0.1 â€“ 4J, 7-300Hz, 6-40W). Low dose CT scanning was performed on POD 3 and POD 90 to assess SFR.
Results: SFR on POD 1 was achieved in 7% of cases. In those 93% of cases with residuals the stone size was less than 3 mm in 39%, 4 â€“ 6 mm in 22%, 7 - 9 mm in 22%, more than 10 mm in 17%. SFR on POD 90 was achieved in 91% of cases. In those 9% of cases with residuals the stone size was less than 2 mm in 75% and 3 mm in 25%.
Conclusions: High rate of artifacts on POD 1 after RIRS is likely to be due to dust accumulations in the collecting system of the kidney. Apparently, more time is required for dust and small fragments wash-out. Seemingly, CT scanning to assess SFR on POD 90 is more reasonable.