Percutaneous Nephrolithotomy (PCNL) For kidney and ureteral stones that are too large (usually larger than 2 centimeters), too numerous, or too dense to be treated by extracorporeal shock wave lithotripsy (ESWL) or ureteroscopy, PCNL (percutaneous nephrolithotomy or stone extraction) offers a minimally invasive method of removing these stones. Historically, large kidney and ureteral stones were removed through open surgery, requiring a large flank incision. Percutaneous nephrolithotomy is performed through a 1-cm skin incision and thus minimizes incision size, pain, blood loss, blood transfusions and shortens hospitalization. This technique also has a higher success rate for clearing all stones in one setting than other techniques such as ESWL, which often require several procedures