All operations were performed or supervised by the same surgeon. Right after the patients in mini-PNL group were placed a 5F ureteral catheter with general anesthesia, they were had a prone position and the access was performed by choosing the optimal calyx to reach the stone following the contrast agent was given. The guide wire was then placed and the stones were broken with a laser lithotripter using a 12F nephroscope (Modular minimally invasive PCNL system, Karl Storz, Tuttlingen, Germany) following the dilatation using an one step dilator with a 16.5F access sheath. When necessary, stones were removed using the stone removal forceps. Right after a 14-Fr nephrostomy tube was inserted and an antegrade pyelography was taken, the operation was terminated.

Following the general anesthesia performed, a safety guide wire was placed and semirigid ureteroscopy (9.5 / 11.5F) was performed. Stones were fragmented using a 270 micron meter laser fiber with the help of 7.5-F fiber optic flexible ureterorenoscope after the placement of ureteral access sheat (9.5 / 11.5 F). Stone fragmentation was accomplished using a laser energy of 0.5-1.5 J and a rate of 5-15 Hz and adjusting this range according to stone hardness. 4.7F JJ stent was routinely placed at the end of the operation because of worries about possible edema etc. due to access sheath. In this group, access sheath could not be placed in 2 patients due to the small diameter of the ureter, and JJ stent was placed, and 2 weeks later, the procedure was performed as it was in the others.

Stone-free conditions were determined by low-dose spiral CT taken in postoperative third month

İntraoperative duration of flouroscopy time