Shockwave Lithotripsy

Shockwave lithotripsy (SWL) is a noninvasive procedure for breaking up kidney stones with high-energy shock waves. SWL is the least invasive and least risky approach to stone treatment.

What is Shockwave Lithotripsy?

Shockwave lithotripsy (SWL) is a noninvasive procedure for breaking up kidney stones with high-energy shock waves. SWL is the least invasive and least risky approach to stone treatment.

The term “lithotripsy” combines the Greek words “litho” (stone) and “tripsis” (friction or rubbing). The goal of SWL is to break the stones into tiny fragments that can easily pass through the urinary tract along with urine. Shock wave lithotripsy is the most common type of treatment for removing kidney stones.

When is shockwave lithotripsy needed?

Usually, stones that form in the kidneys are small enough to pass through the urinary tract and are excreted (passed) along with urine. The main reasons for undergoing the SWL procedure to treat kidney stones are:

  • The stones are too large to pass on their own (greater than 5 millimeters in diameter).
  • The stones block the flow of urine.
  • The stones cause bleeding or a kidney infection.
  • Pain relievers are not effective in treating symptoms.

When can kidney stones be treated with shockwave lithotripsy?

Whether kidney stones can be successfully treated with SWL depends on the size of the stones and their number, position, and type. The hardness and depth of the stone is measured on a CT scan before surgery to predict the likelihood of success.

The procedure produces the best results when the kidney stones are no larger than 2.5 centimeters in diameter. The stones must be visible with an X-ray monitor during the treatment. SWL might not be suitable for patients who are obese or on blood thinners.

What it involves?

Patients lay on their back on a special operating table. After sedation, an gel apparatus that looks like a giant breast implant (see second photo) is placed against the patient’s back side on the site where the kidney stone is present. Loud and powerful sound waves are then produced by various methods, depending on machine type. shockwave lithotripsy

The challenge then is to use the ESWL machine’s X-Rays to identify and target the sound waves onto the stone. On average, 2,000 shock waves are then delivered to the stone and “treatment success” during the operation is noted when a sharply denoted stone at the beginning of treatment on X-Ray is more “fuzzy” or hazy towards the end.

Obviously, the hard part for some patient comes AFTER the treatment, when these fragments have to actually pass.

Thus, our clinical experience and research recommends this treatment to patients with smaller stones (<1cm) so that the fragments after ESWL would be small enough to pass easily.

In those patients who have larger stones or several stones that are targeted with ESWL, we typically recommend placing a stent (a plastic tube resembling a straw) to help prevent the kidney from becoming blocked while the stone fragments are passing down and out.

Placing a stent requires a urologist to look inside the bladder with a cystoscope (camera).

After treatment is complete, patients are awaken and taken to the recovery area. A couple of hours of observation are typical afterwards. Patients are expected to have pain that is normally eased with tablet pain medications.

This surgery is normally done in the outpatient setting and thus patients are sent home same day unless there are other health problems that require an admission to the hospital. 

Length of Surgery

Typically less than one hour, but may be longer depending on how long it takes to sedate a patient, how well the stone is targeted and whether a stent needs to be placed. Like a lot of things in surgery, the actual treatment is quick, but the setup in the OR, patient positioning, sedation and preparation takes often more time than expected.


May be done with moderate sedation General anesthesia (heavy sedation with a ventilator) is recommended for best results. With general anesthesia, we are able to control patient’s breathing and thus allow for better targeting of the stone.

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