3. Sterilization or bacterial culture: Surgical areas is disinfected with 10% povidone-iodine, all surgical instruments are sterilized by high-temperature steam. after renal pelvises are punctured, some urine is extracted for bacterial culture. Stones removed by surgery are fragmented into small fragments, and stored at 36.5 ℃ tubes within a day in order to facilitate the proliferation of bacteria, then grown in culture medium for bacterial culture.