Evaluation of Residual Stones following Percutaneous Nephrostolithotomy

Percutaneous nephrostolithotomy (PCNL) constitutes first line therapy for large and complex renal calculi. However, retained calculi generated by intracorporeal lithotripsy remain a concern because of their potential for growth and future symptoms. Liberal use of flexible nephroscopy identifies residual calculi and increases stone free rates. However, historically the sensitivity of radiographic imaging studies to predict the outcome of flexible nephroscopy has been inadequate. With new, helical, computed tomography (CT) technology, post-PCNL imaging can accurately and reliably detect residual calculi and predict the outcome of flexible nephroscopy, thereby allowing the selective use of second look flexible nephroscopy, and reducing cost and patient morbidity. We review the current recommendations for post-PCNL imaging.