(Extracorporeal Shockwave Lithotripsy, ESWL, Shock Wave Lithotripsy)

Procedure Overview

What is lithotripsy?

Lithotripsy is a noninvasive (the skin is not pierced) procedure used to treat kidney stones that are too large to pass through the urinary tract. Lithotripsy treats kidney stones by sending focused ultrasonic energy or shock waves directly to the stone first located with fluoroscopy (a type of x-ray “movie”) or ultrasound (high frequency sound waves). The shock waves break a large stone into smaller stones that will pass through the urinary system. Lithotripsy allows persons with certain types of stones in the urinary system to avoid an invasive surgical procedure for stone removal.

There are two types of shock wave technology. The original lithotripsy machines sent the shock waves through water in a tub in which the person being treated was placed. This technology remains in use today. More recently, machines have been developed that send shock waves through padded cushions on a table, so the procedure does not involve immersing a person in water.

Other procedures that may be used to treat kidney stones include:

  • urethroscopy or ureteroscopy - endoscopic procedures in which stones in the urethra or ureter may be removed with a device inserted through a short, flexible, lighted tube, called an endoscope

  • percutaneous nephrolithotomy (tunnel surgery) - a surgical procedure for stones which cannot be treated with lithotripsy or endoscopic procedures. It involves the removal of a stone through a thin tube tunneled through a small incision in the back into the kidney.

  • open surgery - a more invasive surgical procedure using a larger incision to directly access the stone

  • stent - a synthetic, tubular device that may be used along with other procedures. A stent may be inserted through a special scope into the urinary tract to allow stones to pass more easily.

About kidney stones:

When substances that are normally excreted through the kidneys remain in the urinary tract, they may crystallize and harden into a kidney stone. If the stones break free of the kidney, they can travel through, and get lodged in, the narrower passages of the urinary tract. Some kidney stones are small or smooth enough to pass easily through the urinary tract without discomfort. Other stones may have rough edges or grow as large as a pea causing extreme pain as they travel through or become lodged in the urinary tract. The areas most prone to trapping kidney stones are the bladder, ureters, and urethra.

Most kidney stones that develop are small enough to pass without intervention. However, in about 20 percent of cases the stone is greater than 2 centimeters (about one inch) and may require treatment. Most kidney stones are composed of calcium; however, there are other types of kidney stones that can develop. Types of kidney stones include:

  • calcium stones
    Calcium, a normal part of a healthy diet used in bones and muscles is normally flushed out with the rest of the urine. However, excess calcium not used by the body may combine with other waste products to form a stone.

  • struvite stones
    Struvite stones, composed of magnesium, phosphate, and ammonia may occur after a urinary tract infection.

  • uric acid stones
    Uric acid stones may occur when urine is too acidic, as in certain conditions such as gout or malignancies.

  • cystine stones
    Cystine stones consist of cystine, one of the building blocks that make up muscles, nerves, and other parts of the body.

How does the urinary system work?

The body takes nutrients from food and converts them to energy. After the body has taken the food that it needs, waste products are left behind in the bowel and in the blood.

The urinary system keeps chemicals, such as potassium and sodium, and water in balance, and removes a type of waste, called urea, from the blood. Urea is produced when foods containing protein, such as meat, poultry, and certain vegetables, are broken down in the body. Urea is carried in the bloodstream to the kidneys.

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