Introduction: After the introduction of CT angiography for living donor kidney evaluation, surgeons have begun to encounter donor candidates more frequently, who are otherwise suitable but have small asymptomatic unilateral kidney stones.
In order to overcome this problem and expand the donor pool, ex-vivo ureterorenoscopy has become a rational approach for the clinician. However, ureteroscopes pose a risk factor in terms of transmission of infection because they are in direct contact with the mucosa. Single-use flexible ureterorenoscopes (su-FU) seem to be a prudent solution to minimize the risk of iatrogenic urinary tract infection during ex-vivo donor kidney stone removal.
Here, we present the surgical technique and outcomes of our ex-vivo su-FU stone removal experience in this video.
Materials and Methods: All potential kidney donor candidates are thoroughly evaluated for any signs or findings suggesting recurrent urinary tract stone disease.  
Small, non-obstructive unilateral kidney stones were detected in two of our donor candidates during the preoperative evaluation with CT scan. Metabolic evaluation revealed no pathological findings and these two patients proceeded to kidney donation.
After laparoscopic harvesting, the donor kidneys were flashed with cold Histidine-tryptophan-ketoglutarate solution and routine bench surgery was performed. Then, the grafts were prepared for stone removal. Ex-vivo ureterorenoscopy was performed by Uscope PU3022A (Pusen Medical, Zhuhai, China) using ice cold saline irrigation solution. After all stones were removed by basket catheter, both kidneys were transplanted. A 4.8 F 16-cm transplant ureteric JJ stent was placed and removed 6 weeks postoperatively. All recipients received tacrolimus/mycophenolate mofetil/prednisone immunosuppression treatment after kidney transplantation. Stone analysis were performed by Fourier Transform infrared spectroscopy technique. 
Results: Two female patients with ages of 28 and 23 underwent left and right laparoscopic donor nephrectomy, respectively. There were 5-mm lower calyx and multiple 2-mm stones in the first patient  and 6-mm upper calyx and 2-mm mid-calyx stone in the second patient . All of the stones were removed en-bloc with basket catheter without using HoYAG laser fragmantation. Operative time of the procedures were 24 and 12 minutes, respectively. There were no peri- and post-operative complications including UTIs in neither donors nor recipients and both recipients were discharged with functioning grafts. Stone analysis revealed mixt type of calcium oxalate (whewellite and whedellite) in the first patient and pure whewellite in the second patient. 
Conclusion: Ex-vivo ureterorenoscopic stone removal in donor kidneys with su-FU seems safe and a feasible procedure without any deterioration of renal allograft function and adverse consequences to the recipients. To the best of our knowledge, these are first reported cases being treated by su-FU.