Determining the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position

INTRODUCTION: Optimal renal access is necessary for ensuring a successful and complication-free percutaneous nephrolithotomy. We describe a technique to determine the angle and depth of puncture for fluoroscopy-guided percutaneous renal access in the prone position. MATERIALS AND METHODS: Forty-two consecutive patients undergoing percutaneous nephrolithotomy from January 2014 had a fluoroscopy-guided access in the prone position. Using the bull's eye technique, the site of skin puncture and the angle of puncture were determined. These parameters were utilized to calculate, mathematically, the depth of the targeted calyx. These measurements were then utilized for puncture. The actual depth of puncture was then calculated. The number of attempts, time of fluoroscopy and difference between estimated and actual depth were noted and analyzed. RESULTS AND LIMITATIONS: There was a difference of 0-3 mm between the estimated and the actual depth at which puncture was made. Single-attempt puncture was possible in >95% cases. No complications related to access were observed. CONCLUSION: By estimating the angle and depth of puncture, the percutaneous renal access becomes technically less challenging.