Ex vivo retrograde stone removal in donor kidneys using an ultra-mini nephroscope prior to renal transplantation in Indonesia: a case series

Introduction: Urolithiasis in donor kidneys presents a relative contraindication for transplantation due to the potential risk of obstruction and impaired graft function. Although less common in renal transplant recipients, obstructive urolithiasis remains a significant concern. Ex vivo stone removal during bench surgery has been explored as a safe and effective method to mitigate this risk. Objective: To present a case series demonstrating the feasibility and outcomes of ex vivo stone clearance using a rigid ultra-mini percutaneous nephrolithotomy (PCNL) set with a 7-Fr nephroscope via a retrograde approach (ureteral access) prior to renal transplantation. Methods: Three donor–recipient pairs underwent laparoscopic living donor nephrectomy via the retroperitoneal approach. The donor kidneys were preserved in ice slush, followed by ex vivo stone fragmentation using a holmium laser via a rigid ultra-mini PCNL set. The procedure was performed through the ureter, eliminating the need for flexible ureteroscopy (FURS). Surgical and postoperative outcomes recorded included cold ischemia time (CIT), serum creatinine levels, urine output, and graft perfusion assessed by Doppler ultrasound. This case series has been reported in line with the PROCESS Guideline. Results: These three cases achieved complete stone removal with no intraoperative complications. The CITs were 54, 45, and 51 min, respectively. All grafts demonstrated immediate function postoperatively, evidenced by a marked decline in serum creatinine within 3 days. Imaging studies confirmed robust perfusion, and there were no signs of ureteral injury, obstruction, or residual stones. At 1-year follow-up, none of the recipients experienced recurrence of nephrolithiasis. Conclusion: Ex vivo retrograde lithotripsy using a rigid ultra-mini nephroscope via a ureteral approach is a safe, effective, and minimally invasive technique for managing renal calculi in donor kidneys before transplantation. Its shorter scope length enhances maneuverability and calyceal access while reducing trauma to the ureter, offering a promising alternative to FURS and pyelotomy in selected cases. The challenge remains to avoid prolonging CIT, which is critical for preserving graft function.