Abstract：Objective:To investigate the value of "powdered stone" theory to flexible ureteroscopy with holmium laser lithotripsy for renal stones.Methods:A total of 462 patients with renal stones were treated with modular flexible ureteroscope combined with Holmium lithotripsy in our hospital between June 2011 and January 2013. There were 385 cases in middle, upper calyx and renal pelvic, 45 cases in lower calyx, 32 cases in mulitple calyxes. The calculi ranged from 10 to 35(15.3±8.4)mm. Modular flexible ureteroscope was used to defect renal stones under epidural anesthesia or general anesthesia, used the 200 μm or 365 μm fiber. The Holmium laser lithotripsy was performed at maximum power of 20 to 45 W (0.8-1.5 J/15-30 Hz)according to the stone hardness. When the total power was constant, the holmium laser parameter was set at high-frequency and low-energy to pulverize stones (ie stone fragments less than 2 mm). F6 double-J tubes and catheters were indwelled routinely postoperatively. Re-examinations with KUB and removal of catheter 2 to 3 days after operation. Re-examinations with B-ultrasonography or KUB or CT 4 weeks after operation to evaluate the stone free rate. Residual stones ≥ 3 mm were regarded as clinical significance of residual stone fragments.Results:The overall success rate of placing the flexible ureteroscope into the ureter and kidney was 98.7% (456/462). Of all the 456 cases, 447 cases were treated with holmium laser lithotripsy. The stone free rate was 97.5% (436/447). The operative time was 27-125 (74.4 ± 21.8)min, the patients were discharged from hospital in 2-8 days (mean 3.5 days) after the operation. No severe complications such as ureteral perforation, ureteral avulsion, hemorrhea occurred. 3 patients developed urinary-derived sepsis in 4-6 h after the operation. These patients recovered in 3-5 days after symptomatic treatment.Conclusions:Flexible ureteroscope with Holmium laser lithotripsy is effective and safe for treatment of renal calcli. Under the guidance of "powdered stone" theory, the higher stone free rate and a lower complication can be achieved, which provides an ideal treatment option for renal stone.
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