A total of 155 consecutive sPCNL cases were included from January 2004 through July 2012 at Seoul National University Bundang Hospital. Percutaneous renal access was routinely obtained by 2 experienced uro-radiologists 1 day before or on the operative day. If the patient previously had a percutaneous nephrostomy, this nephrostomy was used as an access. sPCNL was performed in a prone position by 1 of 4 faculty professors. A rigid nephroscope was used in combination with a ballistic lithotripter, stone forceps, and a suction tube. If needed, a flexible nephroscope and/or ureteroscope were also used for collecting systems that were inaccessible with a rigid nephroscope. In this setting, a Holmium laser and stone basket were used. Temporary drainage was usually maintained with a 14-F nephrostomy catheter.
All patients were evaluated with pre- and post-operative computed tomography (CT). The evaluated preoperative stone parameters included the number, largest diameter, total stone volume, renometry (complete, partial staghorn, or other), average Hounsfield units, and degree of hydronephrosis (normal, mild, moderate, or severe). A complete staghorn stone was defined as a renal pelvic calculi extending into all major calyceal groups filling at least 80% of the renal collecting system, and a partial staghorn stone was defined as a renal pelvic calculi extending into at least two calyceal groups. Stone volume was calculated by length×width×depth×π×0.52. The total stone volume was the sum of all stone volumes. The average Hounsfield unit was measured using the elliptical region of interest incorporated into the largest stone area in a non-contrast axial image [9] (link). “Stone-free” was defined as no evidence of residual stones on postoperative images for 1 month.
All patients were evaluated with pre- and post-operative computed tomography (CT). The evaluated preoperative stone parameters included the number, largest diameter, total stone volume, renometry (complete, partial staghorn, or other), average Hounsfield units, and degree of hydronephrosis (normal, mild, moderate, or severe). A complete staghorn stone was defined as a renal pelvic calculi extending into all major calyceal groups filling at least 80% of the renal collecting system, and a partial staghorn stone was defined as a renal pelvic calculi extending into at least two calyceal groups. Stone volume was calculated by length×width×depth×π×0.52. The total stone volume was the sum of all stone volumes. The average Hounsfield unit was measured using the elliptical region of interest incorporated into the largest stone area in a non-contrast axial image [9] (link). “Stone-free” was defined as no evidence of residual stones on postoperative images for 1 month.
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