Percutaneous Nephrolithotomy (PCNL)
Nephrolithiasis or proximal ureteral obstructions secondary to ureteroliths can result in progressive renal insufficiency, intractable pyelonephritis, ureteral colic, and hydronephrosis. While smaller stones may pass spontaneously or be subclinical and identified incidentally, others require intervention to relieve the obstruction or avoid permanent nephron damage. Nephrotomies, pyelotomies or ureterotomies can be prolonged, invasive, and complicated surgeries, potentially resulting in significant morbidity.22 In humans, PCNL is considered the standard-of-care for nephroliths or proximal ureteroliths too large to be treated with extra-corporeal shockwave lithotripsy (ESWL) or retrograde ureteroscopy with laser lithotripsy,23-26 and has recently been performed successfully in clinical veterinary cases. This minimally invasive procedure aims to minimize morbidity and preserve as much renal function as possible. Success of PCNL has been documented to be between 90-98% in both adult and pediatric humans, dramatically improved from that of ESWL (50-81%).23-26 This technique uses fluoroscopy, guidewires, balloons, and stents in conjunction with endoscopy and lithotripsy (Figure 9).
Figure 9. Percutaneous nephrolithotomy in a dog with a large nephrolith. (A) Following percutaneous, ultrasound-guided renal access, two guidewires (white arrows) are advanced down the ureter, into the bladder, and out the urethra for through-and-through access. A large sheath (black arrow) is placed over the wire to gain access to the renal pelvis and nephroliths (*). (B) Using endoscopic visualization, the lithotripter (white arrow) is used to fragment and remove the nephrolith. (C) Post-procedure fluoroscopic image demonstrating complete removal of the nephrolith. (D) Nephro-ureteral stent (white arrows) placement following lithotripsy.