Extracorporeal Shock Wave Lithotripsy

Extracorporeal Shock Wave Lithotripsy (ESWL) is a new technique that offers an alternative to surgery in people with kidney stones. The ESWL lithotripter was developed by a West German Company. The Food and Drug Administration (FDA) approved its use in the United States in December 1984. Since then over 100,000 patients have been sucessfully treated.

The goal of ESWL is to pulverize stones in the kidney into sand-like particles that can be excreted with little or no pain. This goal is achieved with a simple ESWL procedure approximately 90% of the time. The shock waves are a form of high energy pressure that can travel in air or water. When generated outside the body they pass through the tissues of the body without damaging them, but can puverize a stone inside the kidney. The lithotripter uses water to carry the shock wave because water and the body tissue have the same density. The shock waves pass through both without injury. A kidney stone has a greater density and when the shock wave hits it, the waves scatter and break up the stones.

Shock waves are generated by an electrode or "spark plug". The spark vaporizes a small amount of water, creates a shock wave, and an elliptical reflector focuses each shock wave to a point about a foot and a half above it in a water tank. Two x-ray units called flouroscopes are used to assist in locating the kidney stone and positioning the patient for treatment. It takes an average of about 1500 shock waves to pulverize the stone into sand-like particles. Each shock wave takes less than a thousandth of a second.

Anethesia is used because shock waves while causing little harm are uncomfortable. Once the anesthesia has been administered, the patient is positioned in a reclining seat, and lowered into a large tub of water. The fluoroscopes are positioned on either side of the patient and are used to located the exact location of the stone. Once the stone is in the target area, treatment begins. The whole procedure takes a little over an hour.

Most patients will have mild discomfort after the procedure and will have blood in their urine for several days. This is normal and to be expected. Our experience has been that after treatment, the patient may return to work the following day or at most two days after the procedure. It is essential that follow-up be as directed. The urine should be strained so that the small stone fragments can be collected and later analyzed. X-rays are needed to be sure that all the stone fragments have passed essential.The ESWL lithotripter is a new medical device which will become popular in the next ten years. It is the most advanced form of technology presently available to rid the kidney of stones.