The "old" 15mm renal stone size limit for RIRS remains a clinically significant threshold size.

Abstract

To investigate the performance of retrograde intrarenal surgery (RIRS) for the 1-2cm renal stone size range in comparison to smaller stones. From a data base of 3000 ureteroscopies between 2004 and 2014, 635 consecutive patients underwent RIRS for renal stones. Patients were divided to three groups according to their renal stone size (<10, 10-15, 15-20mm). Preoperative, operative, stone free rate (SFR) and follow-up data were analyzed and compared. The SFR for the three groups was 94.1, 90.1 and 85%, respectively. Patients with renal stone size above 15mm had a statistically significantly lower SFR. The efficiency quotient calculated for stones larger and smaller than 15mm was 83.9 vs. 91.8%, respectively (p<0.01). The mean operative time and hospital stay were longer for patients with renal stones larger than 15mm (73.6±29.9 vs. 53±19.4min, p<0.01 and 2.2±2 vs. 1.8±1.8days, p=0.031, respectively). Moreover, the complication rate was almost two times higher (10 vs 5.4%, p=0.08). Concomitant ureteral stones and older age were independent predictors of failure in the large stone group. While the overall SFR following RIRS for renal stones up to 2cm is generally high, the SFR for 15-20mm stones is significantly lower, with a longer operating time and hospital stay, and a higher complication rate.