A Multicenter Prospective Research on the Treatment of Low Pole Renal Calculus by Flexible Ureteroscope

Inclusion Criteria: * • Subject has provided informed consent and indicated a willingness to comply with study treatments * Subject is 18-70 yrs of age * Subject can be either male or female * Subject has a diagnosis of low pole renal stones according to CT urography(CTU) or intravenous pyelogram (IVP) results * Subject has a single stone 1\~2cm in size (KUB), or multiple stones 1\~2cm in cumulative size (KUB), and is a surgical candidate for the ureteroscopic approach Exclusion Criteria: * • Subject has an active urinary tract infection (e.g., cystitis, prostatitis, urethritis, etc.) * Subject has been diagnosed with a urethral stricture or bladder neck contracture * Subject has been diagnosed with a urinary tract infection related to stone obstruction within two weeks * Subject has severe hematuria that might blur the vision of the endoscopy * Subject is pregnant or in monthly period * Subject has coexistent disease like systemic disease, heart disease, lung disfunction or other diseases that could not tolerate the endoscopic surgery or anesthesia. * Subject has unadjusted diabetes or high blood pressure * Subject has a disorder of the coagulation cascade system that would put the subject at risk for intraoperative or postoperative bleeding * Subject is unable to discontinue anticoagulant and antiplatelet therapy preoperatively (2 weeks) * Subject has been diagnosed with hydronephrosis larger than 3cm according to the B-scan ultrasonography examination * Subject has any kind of anatomic abnormality of the urinary system that might have an influence on the surgery