Single session vs two sessions of flexible ureterosopy (FURS) for dusting of renal pelvic stones 2-3 cm in diameter: Does stone size or hardness play a role in number of sessions to be applied?"

OBJECTIVE To evaluate the stone hardness in predicting the need for single or two sessions of retrograde intrarenal surgery (RIRS) for renal pelvis stones of 2-3 cm in size. MATERIAL AND METHODS Ninety-six patients (64 male and 32 female) with only renal stones (2.5±0.3 cm) underwent RIRS using flexible 7.5 Fr ureteroscope (FURS). The stone hardness was evaluated by preoperative non-contrast computed tomography (NCCT). The patients were divided into two groups based on stone hardness: Group I (n=54) (hard stones - Hounsfield Unit (HU) >1000) and group II (n=42) (not hard stone - HU <1000). The stone-free rate, the operative time, any intra or postoperative complications and the need for second sessions of RIRS were evaluated. RESULTS All stones were successfully accessed. Intraoperative complications were not reported. The initial stone-free rate was 40% in Group I and 95% in Group II after a single session (p=0.01). A second session FURS was needed in 32 cases of Group I (40%) where postoperative CT showed significant residual stone fragments of 6±2 mm, and stone-free rate up to 100 percent. On the contrary only 2 cases from Group II underwent second session FURS (p=0.01). The operative times were 75±15 minutes in Group I and 55±13 minutes in Group II (p<0.01). Six patients (4 in group I and 2 in group II) had postoperative high-grade fever (Clavien Grade II). CONCLUSION Stone hardness had a significant impact on the decision of performing single versus two sessions of FURS for renal pelvic stones of 2-3 cm rather than the stone size alone.