Editorial Comment for Wynberg et al.

T he key to successful percutaneous nephrostolithotomy (PCNL) is a carefully selected access site. Even an average endoscopist can perform successful PCNL with a well-placed access. On the other hand, an expert endoscopist can struggle during a simple PCNL if the access is ill-placed. Recent efforts have focused on ways to improve the accuracy and safety of percutaneous renal access. Some investigators have advocated for use of preoperative CT to help guide intraoperative, fluoroscopically guided access ¹ while others have encouraged the selective use of direct CT guidance ² to precisely puncture an appropriate calix in high-risk patients. A recent report has popularized the use of endoscopic-assisted percutaneous access to precisely puncture a specified calix under endoscopic guidance to avoid under- or overdilation of the tract. ³ Finally, there is evidence to suggest that urologist-directed access may be associated with fewer complications and higher success rates than radiologist-directed access for PCNL. ⁴

To that end, Wynberg and colleagues have revisited an old, little-used technique of retrograde nephrostomy access and modified it to contemporary practice. In this technique, preoperative imaging is used to carefully select the calix that will provide an optimal gateway to the stone burden in the collecting system. Intraoperatively, a puncture wire is guided out of the targeted calix using ureteroscopic and fluoroscopic guidance, thereby potentially improving the accuracy and safety of the nephrostomy tract. The applicability of this technique is contingent on a moderate skin-to-calix distance and accessibility of the selected calix ureteroscopically. A long skin-to-calix distance, as in obese patients, could preclude successful wire puncture because of the long tract, and a stone-filled calix and renal pelvis could necessitate prolonged laser lithotripsy to access the calix. As such, this technique may be best suited to patients with a moderate stone burden accessible through a middle calix that can be entered with a ureteroscope.

Theoretical advantages of this technique are a shorter learning curve and a precisely placed puncture that enters directly onto the renal papilla. Whether these purported advantages are realized remains to be seen, because no large series of ureteroscopic-guided retrograde access have been reported nor have any comparative series been published. Furthermore, the lack of broad applicability mandates that the practitioner be additionally adept at standard antegrade percutaneous access or that he/she involve a radiologist to perform the percutaneous puncture in some cases.

Ureteroscopic-directed retrograde renal access constitutes an alternative for those practitioners without sufficient experience in percutaneous renal access, as well as for those experienced in a variety of access skills, who seek the safest and most reliable urologist-directed technique for accomplishing PCNL. It behooves the urologist performing PCNL to maintain a diverse armamentarium that allows selection of the safest and most expeditious means of accessing the kidney in any given clinical scenario.