MP29-13: Application of the Stone Management According to Size-Hardness (SMASH) score in the selection of patients eligible to Retrograde IntraRenal Surgery (RIRS)
Saturday, May 4, 2024 9:30 AM to 11:30 AM · 2 hr. (US/Central)
302B
Abstract
Information
Full Abstract and Figures
Author Block
Davide Perri*, Umberto Besana, Andrea Pacchetti, Elena Morini, Federica Mazzoleni, Tommaso Calcagnile, Como, Italy, Franck Bruyere, Tours, France, Jean Baptiste Roche, Bordeaux, France, Bernardo Rocco, Milan, Italy, Giorgio Bozzini, Como, Italy
Introduction
EAU guidelines recommend Retrograde IntraRenal Surgery (RIRS) for the treatment of renal stones < 20 mm. Stone hardness is usually an underestimated parameter. The Stone Management According to Size-Hardness (SMASH) score was initially proposed to drive preoperative planning for the treatment of 10-20 mm renal stones between endoscopic and percutaneous approach. We assessed the utility of the score in the selection of the best patients with a stone < 20 mm eligible to RIRS
Methods
Patients with an indication to RIRS for a renal stone were considered. For each patient a mathematical model named Stone Management According to Size-Hardness (SMASH) score was so calculated: hounsfield units (HU) x stone maximum size (cm) / 100. Patients were divided into 2 groups according to stone size and the SMASH score, by using the previously proposed cut-off of 15: patients with a SMASH score < 15 (Group A) vs. patients with a renal stone < 2 cm and a SMASH score = 15 (Group B). In all cases lithotripsy was performed using an Holmium:YAG (Ho:YAG) laser (Cyber Ho, Quanta System). A CT scan after 3 months was performed and stone-free rate (SFR) was defined according to absence or presence of stone fragments < 3 mm
Results
165 patients were considered. 82 patients underwent RIRS for a renal stone with a SMASH score < 15 (49.7%, Group A), whereas 83 patients underwent RIRS for a renal stone < 2 cm and with a SMASH score = 15 (50.3%, Group B). Preoperative parameters were comparable between groups. Mean stone size was 18.3 mm vs. 16.8 mm in Group A vs. B (p=0.14). Mean HUs were 1214 vs. 1104 in Group A vs. Group B (p=0.08). In all cases a ureteral access sheath was used and a ureteral stent was positioned at the end of procedure. Mean total operative time was 48.7 min in Group A vs. 62.2 min in Group B (p=0.03), whereas mean dusting time was 31.5 min in Group A vs. 49.1 min in Group B (p=0.02). 3 months after surgery SFR was 91.8% vs. 82.7% in Groups A vs. B, respectively (p=0.03). Complication rate was 11% in Group A and 10.8% in Group B (p=0.17). Most of complications were fever managed with antibiotic therapy. Renal colic due to fragments migration into the ureter occurred in 5 (6.1%) vs. 8 (9.6%) patients in Group A vs. B (p=0.05)
Conclusions
The mathematical model taking into account HUs of the stone, besides its size, with the proposed cut-off (SMASH score 15), allowed to properly select those patients with a renal stone < 2 cm who could benefit the most from RIRS in terms of stone clearance
Source Of Funding
None
Author Block
Davide Perri*, Umberto Besana, Andrea Pacchetti, Elena Morini, Federica Mazzoleni, Tommaso Calcagnile, Como, Italy, Franck Bruyere, Tours, France, Jean Baptiste Roche, Bordeaux, France, Bernardo Rocco, Milan, Italy, Giorgio Bozzini, Como, Italy
Introduction
EAU guidelines recommend Retrograde IntraRenal Surgery (RIRS) for the treatment of renal stones < 20 mm. Stone hardness is usually an underestimated parameter. The Stone Management According to Size-Hardness (SMASH) score was initially proposed to drive preoperative planning for the treatment of 10-20 mm renal stones between endoscopic and percutaneous approach. We assessed the utility of the score in the selection of the best patients with a stone < 20 mm eligible to RIRS
Methods
Patients with an indication to RIRS for a renal stone were considered. For each patient a mathematical model named Stone Management According to Size-Hardness (SMASH) score was so calculated: hounsfield units (HU) x stone maximum size (cm) / 100. Patients were divided into 2 groups according to stone size and the SMASH score, by using the previously proposed cut-off of 15: patients with a SMASH score < 15 (Group A) vs. patients with a renal stone < 2 cm and a SMASH score = 15 (Group B). In all cases lithotripsy was performed using an Holmium:YAG (Ho:YAG) laser (Cyber Ho, Quanta System). A CT scan after 3 months was performed and stone-free rate (SFR) was defined according to absence or presence of stone fragments < 3 mm
Results
165 patients were considered. 82 patients underwent RIRS for a renal stone with a SMASH score < 15 (49.7%, Group A), whereas 83 patients underwent RIRS for a renal stone < 2 cm and with a SMASH score = 15 (50.3%, Group B). Preoperative parameters were comparable between groups. Mean stone size was 18.3 mm vs. 16.8 mm in Group A vs. B (p=0.14). Mean HUs were 1214 vs. 1104 in Group A vs. Group B (p=0.08). In all cases a ureteral access sheath was used and a ureteral stent was positioned at the end of procedure. Mean total operative time was 48.7 min in Group A vs. 62.2 min in Group B (p=0.03), whereas mean dusting time was 31.5 min in Group A vs. 49.1 min in Group B (p=0.02). 3 months after surgery SFR was 91.8% vs. 82.7% in Groups A vs. B, respectively (p=0.03). Complication rate was 11% in Group A and 10.8% in Group B (p=0.17). Most of complications were fever managed with antibiotic therapy. Renal colic due to fragments migration into the ureter occurred in 5 (6.1%) vs. 8 (9.6%) patients in Group A vs. B (p=0.05)
Conclusions
The mathematical model taking into account HUs of the stone, besides its size, with the proposed cut-off (SMASH score 15), allowed to properly select those patients with a renal stone < 2 cm who could benefit the most from RIRS in terms of stone clearance
Source Of Funding
None