380 CHAPTER 8 Stone disease

Kidney stone treatment: percutaneous nephrolithotomy (PCNL)

Technique

PCNL is the removal of a kidney stone via a track developed between the surface of the skin and the collecting system of the kidney. The first step requires inflation of the renal collecting system (pelvis and calyces) with fluid or air instilled via a ureteric catheter inserted cystoscopically (Fig. 8.7). This makes subsequent percutaneous puncture of a renal calyx with a nephrostomy needle easier (Fig. 8.8).

Once the nephrostomy needle is in the calyx, a guide wire is inserted into the renal pelvis to act as a guide over which the track is dilated (Fig. 8.9). An access sheath is passed down the track and into the calyx, and through this a nephroscope can be advanced into the kidney (Fig. 8.10). An ultrasonic lithotripsy probe is used to fragment the stone and remove the debris.

A posterior approach is most commonly used, below the 12th rib (to avoid the pleura and far enough away from the rib to avoid the intercostals, vessels, and nerve). The preferred approach is through a posterior calyx, rather than into the renal pelvis, because this avoids damage to posterior branches of the renal artery that are closely associated with the renal pelvis. General anesthesia is usual, though regional or even local anesthesia (with sedation) can be used.

Indications for PCNL

PCNL is generally recommended for stones >3 cm in diameter and those that have failed ESWL and/or an attempt at flexible ureteroscopy and laser treatment. It is the first-line option for staghorn calculi,1 with ESWL and/or repeat PCNL being used for residual stone fragments.

For stones 2–3 cm in diameter, options include ESWL (with a JJ stent in situ), flexible ureteroscopy and laser treatment, and PCNL. PCNL gives the best chance of complete stone clearance with a single procedure, but this is achieved at a higher risk of morbidity.

Some patients will opt for several sessions of ESWL or flexible ureteroscopy/laser treatment and the possible risk of ultimately requiring PCNL because of failure of ESWL or laser treatment, rather than proceeding with PCNL up front.

About half of stones >2 cm in diameter will be fragmented by flexible ureteroscopy and laser treatment.

Outcomes of PCNL

For small stones, the stone-free rate after PCNL is on the order of 90–95%. For staghorn stones, the stone-free rate of PCNL, combined with postoperative ESWL for residual stone fragments, is on the order of 80–85%.

1 Segura JW, Preminger GM, Assimos DG, et al. (1994). Nephrolithiasis clinical guidelines panel summary report on the management of staghorn calculi. J Urol 151:1648–1651.

KIDNEY STONE TREATMENT: PCNL 381

Figure 8.7 A ureteric catheter is inserted into the renal pelvis to dilate it with air or fluid.

Figure 8.8 A nephrostomy needle has been inserted into a calyx.

382 CHAPTER 8 Stone disease

Figure 8.9 A guide wire is inserted into the renal pelvis and down the ureter; over this guide wire the track is dilated.

Figure 8.10 An access sheath is passed down the track and into the calyx, and through this a nephroscope can be advanced into the kidney.