Efficacy and safety of fURS in stones larger than 20 mm: is it still the threshold?

INTRODUCTION: The aim of this article was to evaluate the safety and efficiency of flexible ureteroscopy (fURS) in the management of renal calculi larger than 20 mm. MATERIAL AND METHODS: A total of 92 cases with renal calculi were managed with fURS and divided into two groups depending on the size of the stones; <20 mm and >20 mm (Group 1 and Group 2, respectively). The groups were compared with respect to treatment-related parameters including success, complication rates, hospitalization period and need for auxiliary procedures with an emphasis on the rate of infections. Success rates were also compared in each group according to stone location. RESULTS: Overall success rates after 3 months showed that stone-free rates in both groups were 84.1% (< 20 mm) and 58.33% (>20 mm) respectively (p = 0.008). The success rates of upper/mid pole (100% vs. 80%) and pelvis stones (83.3% vs. 75%) showed no statistically significant difference (p = 0.5, p = 0.51 respectively). Success rates for stones located in the lower pole were 75% vs. 14.28% respectively (p = 0.008). The rate of infectious complications was significantly higher in cases undergoing fURS for relatively larger stones (22.9%) as compared to smaller calculi (6.8%) (p = 0.032). No complications were recorded in Group 1, while 2 cases in Group 2 (4.1%) developed ureteral stricture. CONCLUSIONS: Despite the relatively low stone-free rates in lower pole stones, our current results indicate that fURS can be an effective and safe treatment alternative to PNL in larger renal stones (>20 mm) located in the pelvis and in the upper part of the calyceal system of the involved kidney.