Kidney Stones - Prevention

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Percutaneous Nephrolithotomy

Percutaneous nephrolithotomy may be used when ESWL is not available or effective (e.g., if the stone is very large, in an inaccessible location, or is a cystine stone). It is also preferred over ESWL for stones that have remained in the ureter for more than 4 weeks.

It is more effective that ESWL for patients with severe obesity and appears to be safe for the very elderly and the very young. Success rates have been reported to be about 98% for kidney stones and 88% for ureteral stones. They may vary according to the technique and patient group. For example, success rates are slightly lower in children, although the procedure can be done safely in young patients. Long-term effects are unknown.

A typical procedure is as follows:

• The surgeon makes a tiny incision in the back and creates a tunnel directly into the kidney.
• The surgeon then inserts an instrument called a nephroscope through the tunnel.
• The stone is located and removed. If it is large it is destroyed using ultrasound, lasers, or other devices and the fragments are then removed. (An advantage of percutaneous nephrolithotomy over ESWL is that the surgeon is able to remove the stone fragments directly instead of relying on their natural passage from the kidney.)
• Generally, patients stay in the hospital for 5 or 6 days and may need a small device called a nephrostomy tube left in the kidney during the healing process.

Devices Used to Destroy Stones. For large stones, some type of energy device may be needed to break the stone into small pieces. They are referred to as intracorporeal lithotripsy devices (meaning stone breakers within the body). The energy source may be one of the following:

• Ultrasound is employed through a rigid nephroscope and results in a stone-free rate of 94%. It is currently the preferred method.
• A more recent device uses a combination pneumatic drill and ultrasound with stone-free rates of 80 - 89%. It may be prove to be superior to ultrasound alone and to be effective against stones of all types.
• The holmium laser literally melts the stones and destroys up 100% of stones of any composition. It uses a flexible nephroscopy and has an excellent safety record. It should be used sparingly, however, and particularly cautiously with large uric acid stones until more is understood about this effect. Another device, the erbium: YAG laser, is showing promise in lithotripsy but is not currently practical.