Renal Access for Percutaneous Nephrolithotomy: Where Are We Today?

By Sri Sivalingam, MD, MSc, FRCSC

Percutaneous nephrolithotomy is the current gold standard for large renal stones > 2 cm. The initial step in this procedure is obtaining renal access, which is often the most challenging part of the procedure and can directly impact the safety and efficacy of stone removal.

The approach to obtaining renal access varies among endourologists who routinely perform this procedure. Often, interventional radiologists are asked to obtain the initial access prior to dilating the tract. Practically, this approach can be cumbersome and inefficient, as the patient must undergo two separate procedures, and the tract placement may not be ideal.

A recent survey of Endourological Society members found that the majority of endourologists (approximately 76 percent) obtained their own renal access, in contrast to a previous survey of members of the North Central Section of the American Urological Association, which reported that only 11 percent of urologists obtained their own access.

This disparity may be attributable to inherent biases within the surveyed populations. In the survey of endourologists, however, fellowship training in endourology was a significant determinant of whether urologists obtained their own access, while number of years in practice had no influence.

Majority in Survey Use Antegrade Approach

Obtaining the ideal access is paramount to successful stone removal, and over the years, the various techniques have been refined. At Cleveland Clinic, we have expertise in the full range of available techniques, including pure antegrade access, pure retrograde access and a combined antegrade-retrograde access.

According to the survey of endourologists, 68 percent established access using the classic antegrade approach, 19 percent utilized a retrograde approach and 12 percent utilized a combined approach (Figure 1). Patient positioning also varied, with the majority (85 percent) of endourologists favoring the prone position (Figure 2).

Figure 1. Percutaneous renal access approach for nephrolithotomy among endourologists. Figure 2. Patient positioning for percutaneous nephrolithotomy among endourologists.

The classic antegrade approach begins with placement of a ureteral access catheter into the ipsilateral ureter while the patient is in supine position; subsequently the patient is repositioned in prone to establish percutaneous access. Renal access is obtained with a 21-gauge Chiba needle (Cook Medical; Bloomington, IN) under fluoroscopic guidance (triangulation/bull’s-eye technique), and once the calyx is entered and access secured, tract dilatation is performed. Postoperative drainage is typically maintained via a nephrostomy tube.

We recently demonstrated safety and efficacy with a purely retrograde access technique. This technique is especially useful in a nondistended collecting system and precludes prone positioning. It is performed with the patient in a modified low lithotomy position with the ipsilateral flank wedged upward and prepped.

Cystoscopy and retrograde pyelography is performed, and a Lawson™ steerable catheter is advanced into the optimal calyx. A puncture wire is then advanced retrograde through the catheter under fluoroscopy until it emerges through the skin at the flank. An assistant then grasps and gently pulls the wire until the catheter emerges through the skin, and the puncture wire is removed. A stiff guide wire can then be placed antegrade for through-and-through renal access. A double-J ureteral stent is placed, which obviates postoperative nephrostomy tube placement. The patient is then gently repositioned in a lateral decubitus position, and tract dilatation and nephrolithotomy are performed.

Details of the Combined Approach

A third technique is a combined antegrade-retrograde approach. This begins with placement of a ureteral access sheath with the patient in prone position. An assistant performs ureteropyeloscopy and navigates the ureteroscope into the calyx of choice.

The primary surgeon then utilizes an antegrade approach to obtain access, by which the 21-gauge Chiba needle is placed into the preselected calyx with the tip of the ureteroscope as the target, and needle entry is confirmed by direct visualization. A guide wire is then placed though the needle, and once visualized with the ureteroscope, the guide wire is grasped and brought out through the external urethral meatus, establishing a through-and-through access. The tract is dilated and nephrolithotomy is completed with the patient in prone position. A ureteral stent is often placed, without a nephrostomy tube, at the end of the procedure.

While each of these techniques has inherent advantages and disadvantages, the approach of choice must be based on surgeon experience and comfort. Although some variability in operative time, radiation exposure, patient positioning and postoperative drainage may exist, outcomes data show that all these approaches are safe. Further comparative evaluation of these techniques will help determine which is most efficacious in different clinical scenarios.

Dr. Sivalingam is an associate staff member of Cleveland Clinic Glickman Urological & Kidney Institute’s Department of Urology.