Prospective Comparative Study of the Efficacy and Safety of New-Generation Versus First-Generation System for Super-Mini-Percutaneous Nephrolithotomy: A Revolutionary Approach to Improve Endoscopic Vision and Stone Removal.

PURPOSE: The study sought to compare the procedural and clinical results of super-mini-percutaneous nephrolithotomy (SMP) with the use of first- and new-generation devices.

METHODS: A prospective, comparative cohort study was carried out between February 2013 and January 2017. Patients who underwent either first- or new-generation SMP were eligible for the study. Inclusion criteria were adult patients with renal stone <4 cm, or in pediatric patients with renal stone <2.5 cm with a history of failed extracorporeal shockwave lithotripsy. The primary outcome of the present study was the operating time, which was calculated from the starting of percutaneous puncture to the wound closure. Secondary outcomes were the stone-free rate (SFR), blood loss (hemoglobin decrease), hospital stay, and postoperative complications.

RESULTS: One hundred fifty-six consecutive patients who underwent SMP for treatment of renal stones were eligible for the study, with the first 85 patients undergoing SMP with the first-generation device, and the remaining 71 consecutive patients being treated with the new-generation SMP system. The two groups of patients had comparable demographic data, including age, BMI, stone size, Guy's score, stone location, comorbidities, grade of hydronephrosis, and history of urinary tract infection. The new-generation SMP had a shorter operation time (39.3 vs 50.5 min, p = 0.016) and shorter postoperative hospitalization time (2.1 vs 3.0 days, p < 0.001) than the first-generation SMP. No significant difference existed between the two groups for SFR, hemoglobin decrease, and tubeless rate. The overall operative complication rates using the Clavien-Dindo grading system were similar between the two cohorts of patients.

CONCLUSION: The clinical outcomes of the new-generation SMP in patients with moderate-sized renal stone were comparable when compared with the first-generation SMP. New-generation SMP system using an irrigation/suction sheath improved intraoperative irrigation, a more efficient hydrodynamic mechanism for retrieval of fragments. This may account for the shorter operative time than the first-generation SMP system demonstrated in this study.