Stone free outcomes of flexible ureteroscopy for renal calculi utilizing CT imaging

Abstract

Objectives To assess stone free rates following URS for renal calculi at our institution using low dose renal only CT (LDCT). Methods A retrospective review of patients undergoing flexible URS for renal stones only with subsequent CT scan within 3 months. Meticulous basketing of all stone fragments was performed whenever possible. A “true” zero fragment SFR was determined by reviewing the CT scan and radiologist's report. Patients with nephrocalcinosis (as determined by visual inspection of papilla at the time of URS) were assigned the “stone free” category. Results Flexible URS was performed in 288 renal units of 214 patients with renal calculi from 2013 to 2016. Median pre-operative stone size was 6.2mm with the average kidney containing 6.4 stones. An access sheath was used in 92% of cases. A total of 73% (209/288) renal units were completely stone free by CT assessment. Patients with residual fragments were as follows: 1mm in 2% (7/288), 2-4 mm in 16% (46/288), and >4 mm in 9% of kidneys (26/288). Conclusions The true stone free rate in patients undergoing flexible URS for renal calculi utilizing active basketing of fragments as determined by strict CT assessment was 73%. In patients with residual fragments, the majority are 2-4 mm in size making URS a treatment option for renal calculi with excellent stone free results.