Retrograde vs. antegrade fl exible nephroscopy for detection of residual fragments following PNL: A prospective study with computerized tomography control.

Introduction: The main aim of stone surgery is to establish stone free status. Performing fl exible nephroscopy is an effective tool in this manner. The aim of this study was to evaluate the role of retrograde fl exible nephroscopy for detection of residual fragments following percutaneous nephrolithotomy (PNL) in comparison with antegrade approach.

Materials And Methods: Data of 137 patients underwent ECIRS was collected prospectively. In all cases following stone clearance, collecting system was checked for residual fragments. First antegrade than retrograde fl exible nephroscopy was performed and success rates to reach all calices and detection of residual fragments were noted. All patients underwent CT and success rate of antegrade and retrograde approaches were compared. PPV and NPV of retrograde approach to detect residual fragments were calculated.

Results: Antegrade and retrograde nephroscopy successfully accessed all of the calices in 101 (73.7%) and 130 (94.9%) patients respectively (p<0.0001). Residual fragments were observed in 18 (13.1%) patients following antegrade fl exible nephroscopy. Retrograde approach identifi ed residual stones in 17 more cases. These cases were treated with fl exible nephroscopy or secondary percutaneous tract. Postoperative CT revealed residual stones in 10 (7.3%) patients. PPV and NPV of retrograde fl exible nephroscopy were 83.3% and 96.2%.

Conclusions: Flexible nephroscopy effectively detects residual fragments following PNL. Retrograde approach was more successful than antegrade approach to reach all calices. We recommend performing retrograde fl exible nephroscopy following PNL especially in complex cases as it has the potential to increase SFR, decrease the need for second look surgery and unnecessary postoperative imaging.