Extracorporeal shock wave lithotripsy (ESWL) for kidney stones
Extracorporeal shock wave lithotripsy (ESWL) uses sound waves (also called shock waves) to break a kidney stone into small pieces that can more easily travel through the urinary tract and pass from the body. See an illustration of ESWL
You lie on a water-filled cushion, and the surgeon uses X-rays or ultrasound tests to precisely locate the stone. High-energy sound waves pass through your body without injuring it and break the stone into small pieces. These small pieces move through the urinary tract and out of the body more easily than a large stone.
The process takes about an hour.
You may receive sedatives or local anesthesia.
Your surgeon may use a stent when your stones are larger than 2.5 cm (1 in.). A stent is a small, short tube of flexible metal mesh that holds the ureter open. This helps the small stone pieces to pass without blocking the ureter.
What To Expect After Treatment
ESWL is usually an outpatient procedure. You go home after the treatment and do not have to spend a night in the hospital. It may take a few days or weeks for all the stone fragments to pass from your body. You may have mild pain as the small fragments pass through the urinary tract.
Why It Is Done
ESWL may be used on people with a kidney stone that is causing pain or blocking the urine flow. Stones that are between 4 mm (0.16 in.) and 2 cm (0.79 in.) in diameter are most likely to be treated with ESWL. ESWL may work best for kidney stones in the kidney, not in the ureter. It may be harder for ESWL to break up a stone that has moved into the ureter, although this is still possible. Your surgeon may try to push the stone back into the kidney with a small instrument (ureteroscope) and then use ESWL. ESWL usually is not used if you:
Are pregnant. The sound waves and X-rays may be harmful to the fetus. Have a bleeding disorder. Have a kidney infection, urinary tract infection, or kidney cancer. Have kidneys with abnormal structure or function. How Well It Works
After ESWL, stone fragments usually pass out of the body within a few weeks. If you have a larger stone, you may need more ESWL or other treatments. ESWL machines can be low- or high-energy. Low-energy machines cause less discomfort, but you may need more treatments before the stone is broken into pieces small enough to pass. Kidney stones form again about 20% of the time after ESWL. ESWL does not replace the need for the preventive treatment of kidney stones, such as drinking a lot of fluids.
What To Think About
ESWL does not successfully treat cystine kidney stones. These stones do not break up easily. ESWL is a safe procedure and may be used on children and on individuals with only one working kidney. ESWL should not be used if you have a pacemaker unless a cardiologist has determined it is safe.