What is Extracorporeal Shock Wave Lithotripsy?

Extracorporeal shock wave lithotripsy (ESWL) is a non-invasive treatment for kidney stones and gallbladder stones that are too large to be passed through the urinary tract. This procedure uses shock waves to break the stones into small pieces, making them easier to pass via the urinary tract. Extracorporeal shock wave lithotripsy is a very safe alternative to open surgery, which is now rarely used as a treatment for kidney stones.

Extracorporeal shock wave lithotripsy uses high-intensity shock wave pulses to break large, mineralized kidney stones or gallbladder stones into smaller pieces. Shock waves are applied using an external unit that is aimed at the kidneys. At the beginning of the procedure, the patient lies down on a water-filled support that is placed directly beneath the kidneys.

The next phase involves an ultrasound or X-ray, which is used to pinpoint exactly where the kidney stones are located and ensure that the shock waves are targeted correctly. The shock waves themselves can be generated in three different ways: via electrohydraulic, piezoelectric or electromagnetic methods. Each method involves the application of an electric current to create shock waves and target them at the location of the stones. For most people with medium or large kidney stones, ESWL treatment is sufficient to break the stones into small enough pieces that they can be passed in the urine.

ESWL requires only a low level of anesthesia, which makes it safe for people who cannot tolerate deep anesthesia. This procedure also is safe and non-invasive enough to be carried out on young children. In addition, extracorporeal shock wave lithotripsy is safe for someone who has had a kidney removed or whose kidney function is less than 100 percent.

Although this procedure is very safe in comparison to open stone-removal surgery, there are some associated risks. Someone who wears a pacemaker or who has kidney cancer, a structural kidney abnormality or a kidney or urinary infection cannot undergo extracorporeal shock wave lithotripsy. He or she must either undergo an alternative treatment for kidney stones or postpone the procedure until it is considered safe. A woman who is pregnant or suspects she might be pregnant should avoid this procedure, because the shock waves and X-rays used in ESWL can cause damage to a developing fetus.

There also are several complications that might arise following ESWL. These include bleeding, infection or blockage of the urinary tract. Someone with complications might experience severe pain or persistent pain, blood in the urine or painful urination. Any of these symptoms should be reported to a doctor promptly.