Super-mini percutaneous nephrolithotomy for the treatment of kidney stones: a preliminary report of 31 cases

Objective To describe our novel modified technique of super-mini percutaneous nephrolithotomy (SMP) and to report the safety,indication,and technique of this procedure for the treatment of kidney stones.Methods SMP was performed on 31 patients after proper consents were obtained.The procedure was done using a 7 F mini-nephroscope with 3.3 F working channel (Hawk,China) and a 10 or 12 F nephrostomy sheath that possessed suction-evacuation function.The sheath was connected to a specimen container then onto a negative pressure aspirator.Lithotripsy was performed using holmium:YAG laser and/or pneumatic lithotripter.Among our 31 patients,5 were children,11 were failed extracorporeal shock wave lithotripsy (ESWL) or retrograde intrarenal surgery,and 3 patients had solitary kidney.The stones in low pole,mid pole,upper pole,pelvic,pelvic-low pole,pelvic-upper ureter were 12,2,1,7,6,3 cases,respectively.The mean stone size was (1.9±0.6) cm.Results The average operative time was 54±30 (25-140) min.The mean hemoglobin drop was (12.2±9.5) g/L.Three cases require two nephrostomy tracts,and the remaining 28 required only single tract.The stone-free rate after 1 day was 94％ (29/31).One patient required a second look SMP,and another one required auxiliary ESWL.The stone-free rate at 1 month was 100％.Fever occurred in 2 cases.No one needed blood transfusion.The mean postoperative hospital stay was (1.8±0.8) d.None of the patients had nephrostomy tube and 27 patients had neither double J stent nor Foley catheter placed.Two patients had both renal stone and ipsilateral ureteral stone treated simultaneously,and these 2 patients had ureteral catheter for 24 h.There were 2 patients underwent concurrent endopyelotomy for ureteropelvic junction obstruction and these 2 patients had indwelling ureteral stents for 8 weeks.Conclusions Our SMP with a suction-evacuation system is a safe and efficacious procedure for renal stones smaller than 2 cm.It might be particularly suitable for children,patients with lower pole stones,and residual stonse after previous surgical interventions. Key words: Kidney calculi ;  Nephrostomy, percutaneous ;  Lithotripsy ;  Super-mini percutaneous nephrolithotomy;  New technique