Extracorporeal shock wave lithotripsy (ESWL) uses high-energy shock waves to break up kidney stones so they can be passed more easily through urine. Kidney stones are solid masses of crystals that form when urine becomes too concentrated. ESWL is the most frequently used procedure for treating kidney stones, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

This technique is also sometimes used to break up stones in the gallbladder and pancreas. ESWL has also been used as an experimental therapy in treating gallstones, pieces of hard matter that form when components of bile (cholesterol and bilirubin) crystalize in the gallbladder.

Also known as lithotripsy, ESWL may be performed on either an inpatient or outpatient basis in a hospital, outpatient clinic or mobile treatment unit. Patients are typically instructed not to eat or drink anything for at least six hours prior to the procedure. They may also be asked to alter their medication regimen for several days before undergoing ESWL.

The procedure itself is usually performed in one of two ways. In the more common method, patients lie on a soft cushion as the waves pass through them. In other cases, patients sit in a tub of lukewarm water as the shock waves are sent into their bodies.

Between 1,000 and 2,000 shock waves are usually required to crush the stones, which are pulverized into pieces as small as grains of sand. The process itself is painless, although patients commonly experience temporary side effects such as minor bruising or blood in the urine.  ESWL treatment usually takes between 45 minutes and one hour.

Between 70 and 90 percent of patients who undergo ESWL are free of stones within three months of treatment, according to the National Kidney Foundation. Treatment is most effective for stones located in the upper portions of the urinary tract, such as the kidney or upper part of the ureter (narrow duct that moves urine from the kidney to the bladder).

Extracorporeal shock wave lithotripsy (ESWL) is a technique in which high-energy shock waves are sent through the body to break up kidney stones so they can be passed more easily through urine. ESWL provides a nonsurgical alternative for treating kidney stones.

Kidney stones are solid masses of crystals that form when urine becomes too concentrated, which is often caused by a lack of fluid. Most of these stones pass through the urinary tract on their own and require no additional treatment. However, some stones become so large that they cannot be passed without first reducing the size of the stone. ESWL can help reduce the size of such stones.

The procedure may also be recommended when the stones cause constant pain, block urine flow, damage kidney tissue, cause an ongoing infection of the urinary tract (UTI) or cause constant bleeding. It is the most frequently used procedure in treating kidney stones, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

ESWL is also sometimes used to break up stones in the bladder and pancreas. The technique has also been used as an experimental therapy in treating gallstones, pieces of hard matter that form when components of bile (cholesterol and bilirubin) crystallize in the gallbladder. ESWL is usually recommended for patients with fewer than three gallstones. Favorable predictors of success include good gallbladder function and low body mass. ESWL appears to leave fragments of stone in the gallbladder that do not dissolve unless the patient receives medications to dissolve cholesterol gallstones. ESWL therapy may not be effective in treating gallstones formed by bilirubin.

Also known as lithotripsy (a Greek word meaning "stone crushing"), ESWL uses a special machine (lithotripter) to generate the shock waves that dissolve the stones. ESWL treatment is performed in one of two ways. In the more common method, patients lie on a soft cushion as the waves pass through them. In other cases, patients sit in a specially designed tub filled with lukewarm water during the treatment.

The major advantage of ESWL therapy is that it is safer and less invasive than surgery, resulting in fewer complications, a shorter hospital stay and recovery time, and lower costs.

However, not all kidney stones can be treated using ESWL therapy. Factors that influence the potential effectiveness of ESWL include stone size, location and composition. In addition, the anatomy of some patients may prevent the physician from obtaining a clear x-ray image of the stone. In such cases, alternative methods of removal may be necessary.

Between 70 and 90 percent of patients who undergo ESWL are free of stones within three months of treatment, according to the National Kidney Foundation. Treatment is most effective for stones located in the upper portions of the urinary tract, such as the kidney or upper part of the ureter, the long duct that transports urine from the kidney to the urinary bladder.

ESWL is not the only method of reducing kidney stones. In some cases, medications may be used to achieve this effect. In addition, surgery may be performed to remove stones. Percutaneous stone removal involves removing the stones through a tube inserted through a small incision in the back and into the kidney. Ureteroscopic stone removal allows the surgeon to remove stones in the lower urinary tract by passing a hollow tube-like device (ureteroscope) into the bladder and ureter. A device is then passed through the tube and the stones are removed.

Patients who have symptoms of kidney stones may have blood tests, urine tests, x-rays (e.g., computed axial tomography scans) or other tests (e.g., magnetic resonance imaging) to determine the source of these symptoms. If a kidney stone is diagnosed, the physician may schedule an ESWL. It is important for women to tell the physician if they are pregnant, as ESWL should never be performed during pregnancy.

Initial research suggests that ESWL is effective in treating kidney stones in children. However, follow-up studies are necessary to ensure that there are no lingering effects in the pediatric population.

Patients are typically instructed to refrain from eating or drinking for at least six hours prior to the extracorporeal shock wave lithotripsy (ESWL) procedure. They may also be asked to alter their medication regimen for several days before undergoing ESWL. In particular, patients should refrain from taking aspirin or other drugs that might affect blood clotting, such as anticoagulants.  Patients should report any allergies to the physician prior to the procedure, especially if they are allergic to general anesthesia.

Extracorporeal shock wave lithotripsy (ESWL) may be performed on either an inpatient or outpatient basis in a hospital, outpatient clinic or mobile treatment unit. Patients usually receive some kind of anesthetic to help reduce discomfort. General anesthesia renders the patient unconscious for the procedure, whereas regional anesthesia blocks pain in an area of the body (without loss of consciousness) and local anesthesia blocks pain in a specific part of the body (also without loss of consciousness).

In the more common method of ESWL, the patient lies on a soft cushion or a membrane through which the machine-generated shock waves pass before penetrating the body. In the alternative method, patients sit in a tub of lukewarm water while x-rays or ultrasound are used to pinpoint the location of the stones.

Once the stones have been located, the shock waves are focused on that area of the body. The waves pass through skin and body tissues until they reach the denser material of the kidney stones. Between 1,000 and 2,000 shock waves are required to crush the stones, which are pulverized into pieces as small as grains of sand. The physician can view the ultrasound or x-ray image to assess the progress of the stone’s dissolution.

The shock waves are painless and will not be felt by the patient as they pass through the body. However, each shock wave produces a loud sound, and patients are usually asked to wear protective earphones to avoid hearing damage.

Patients who have extracorporeal shock wave lithotripsy (ESWL) on an outpatient basis may be required to remain under a physician’s supervision for an hour or two following the procedure before being released to someone who can drive them home.  During this time, patients will be encouraged to drink plenty of fluids to help the residue of the kidney stones pass more easily through the urine. Some patients may be given intravenous (I.V.) fluids for this purpose.

Patients are typically able to move about freely and without pain immediately following the treatment. However, it may be a day or two before they can fully resume their routine activities. Petechiae (small bruises) on the abdominal wall are common, especially in thin individuals. In addition, patients may have blood in their urine for a few days following treatment. These complications can be reduced by avoiding aspirin and other drugs that affect blood clotting (e.g., anticoagulants) for several weeks following ESWL.

As is the case with all procedures that involve the use of anesthesia, patients who receive anesthesia prior to extracorporeal shock wave lithotripsy (ESWL) may develop an allergic reaction to the drug.

In addition, recent  research indicates that ESWL appears to increase the risk of developing hypertension (high blood pressure) and diabetes later in life in some patients. However, hypertension risk was only associated with the treatment of both kidneys, and diabetes risk was associated with treatment intensity, the number of shock waves administered and the size of kidneys, with smaller kidneys sustaining greater damage.

Otherwise, there are few significant risks associated with ESWL. In rare cases, bleeding may occur around the kidney that is significant enough to require a transfusion.

Patients with pacemakers should notify the physician before ESWL treatment. The lithotripter machines can interfere with pacemaker function. Therefore, this method of treatment may not be recommended.

In some cases, fragments of kidney stone will be left in the urinary tract, resulting in obstruction despite the procedure. Additional treatments may be needed to further break up these stone fragments.

Exclusion criteria for ESWL include pregnancy, platelet abnormalities, abnormal blood clotting parameters and vascular lesions of the liver.

Patients who experience certain symptoms following the procedure may have an infection or blockage. Patients should contact their physician immediately if they experience:

• Excessive urge to urinate
• Inability to urinate
• Excessive blood in the urine
• Extreme pain
• Fever and chills

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to extracorporeal shock wave lithotripsy (ESWL):

1. Will ESWL effectively treat my kidney stones?
   
   
2. Why is ESWL the best treatment for my condition?
   
   
3. Which of the two methods of ESWL will I undergo?
   
   
4. How should I prepare for the procedure?
   
   
5. Will I experience any pain or discomfort during ESWL?
   
   
6. How long will my ESWL procedure take?
   
   
7. Will I need to take any precautions during the treatment?
   
   
8. When will I be able to resume my normal activities?
   
   
9. What side effects and complications might I experience with ESWL?
   
   
10. How many ESWL sessions will I require?