BERKELEY, CA (UroToday.com) - Percutaneous nephrolithotomy (PCNL) has evolved significantly in the last 30 years.
Indications for its use include the treatment of stones larger than 2cm; stones hard enough to be treated, or stones that failed to be disintegrated by other therapeutic modalities such as shock waves or ureterolithotripsy; and stones located in anomalous kidneys. The most common representative of the later is the horseshoe kidney.
There are certain issues that need to be considered regarding puncturing a horseshoe kidney. First of all, the anatomy of the pelvicalyceal system is different from the normally developed kidney. The orientation of the calyces is opposite, a fact that may confuse the surgeon who has to correctly identify a posterior calyx into which he has to insert the needle. Injecting air through a ureteral catheter to the pelvicalyceal system may be of some assistance, as air is entrapped in a posterior calyx when the patient is in a supine position.
Another difficulty is the fluctuation in horseshoe kidney vasculature. In the author’s opinion, no specific test is needed preoperatively to define the exact vascular anatomy of a horseshoe kidney prior to PCNL. The surgeon should remember that his puncture should be made more medially, closer to the sacrospinalis muscle, and more perpendicular to the horizontal axis of the body. Puncturing the upper pole of the kidney, a technique that is easier in the horseshoe kidney due to the lower position of the kidney in the abdomen, is associated with less bleeding. This had to do with the minimal major vascular supply these kidneys have in the upper pole. Finally, surrounding anatomy can be problematic in a patient with a horseshoe kidney. Retrorenal colon is common in these patients and we strongly recommend that a computed tomography be performed in all to minimize the possibility of a colon injury.
While there are many papers on the outcome of PCNL in patients with horseshoe kidneys, our study showed, in a multivariate analysis, that the existence of a staghorn stone is associated with a poor stone-free outcome. Although the current study is retrospective in nature, it is the only one that tested various parameters that may affect the outcome of this operation in a certain number of patients - a fact that may be warrant further field research in the form of prospective multicenter studies.
Written by:
Andreas Skolarikos, MD, PhD, FEBU as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Percutaneous nephrolithotomy in horseshoe kidneys: Factors affecting stone-free rate - Abstract
UroToday.com Stone Disease Section