Value of Intraoperative Ultrasound in Decreasing Incidence of Residual Radiolucent Stones Post- Percutaneous Nephrolithotomy

Background: Percutaneous nephrolithotomy (PCNL) is the gold standard treatment for large renal calculi. The primary goal of treatment is absolute clearance of stone. The incidence of residual stones after PCNL ranges from 10% to 60% and may be higher in radiolucent stones. Aim of work: Our objective was to assess the effectiveness of the use of ultrasound during PCNL in patients with radiolucent stones in reducing the incidence of residual fragments postoperatively. Patients and Methods: This was a single center prospective study over a 6 year period. We identified 86 patients undergoing PCNL with radiolucent stones. Ultrasound was used in conjunction with traditional fluoroscopy to identify residual fragments. Each patient had a first day post-operative computed tomography to assess for residual fragments. The sensitivity of ultrasound with fluoroscopy was compared to clinically or radiologically [CT] detected residual fragments. Results: Our overall stone clearance rate was 82.6% [as evidenced by postoperative CT]. The sensitivity of intra-operative ultrasound when compared to postoperative CT was 95.8%, specificity 40.0%, the positive predictive value 88.3% and negative predictive value 66.7% Conclusions: The use of intra-operative ultrasound during PCNL for radiolucent stones may help in reduction of postoperative imaging. However, future studies are recommend.