Lithotripsy

Extracorporeal Shock- Wave Lithotripsy or ESWL, (pronounced ess-wall), commonly referred to as lithotripsy, is clearly one of the most revolutionary developments in the history of medicine. It was introduced in 1982 after its development in Germany. It has made the non-invasive treatment of many stones possible in an outpatient setting under sedation. The concept is one of focusing shock waves on the stone. The shock wave is generated by a high voltage discharge through a water medium. Situating the shock generator in a curved wave lens allows the shock waves to be concentrated on the small area where the stone is, as a magnifying lens does to sunlight. The stone is broken apart with a very high intensity shock waves, while surrounding structures suffer only minor effects. Dense structures such as stones receive the maximum disruptive forces, while adjacent soft tissues such as kidney and intestines are merely bruised. X-ray and/or ultrasound are used to image and center the stone for treatment. The original lithotriptor, the Dornier HM-3 required the patient to be immersed in a water bath and have either general or spinal anesthesia. It also required a dedicated room usually in a hospital. Advancements in technology have resulted in decreased size, cost, and inconvenience. Patients now generally have sedation and lie on a table without immersion in water. Our present unit is transportable and is used both at MAUI and several local hospitals.

Lithotripsy can be used on virtually any part of the urinary tract with good results. Several treatments may be necessary for some stones, but that is frequently easier on the patient than other methods. The patient with a solitary stone of less than 2 cm should have a 80-90% chance of success with one procedure. This would mean complete disintegration of the stone or fragmentation into particles small enough to pass. Some stones, such as cystine or uric acid, are so hard they are difficult to treat with lithotripsy, but the majority of stones are amenable to this technology. Patients who are pregnant or who have bleeding difficulties should not be treated with ESWL.

After ESWL one usually feels sore and there may be some blood in the urine. Particles of stone will usually be passed and can be saved for analysis. Occasionally there may be severe pain from particles blocking the ureter or fever which may necessitate placement of a stent in the ureter to relieve obstruction. Most of the time, however, patients do quite well with only minimal discomfort. Occasionally, your doctor will recommend placement of a stent (an internal drainage tube from the kidney to the bladder) to help in visualizing the stone or to allow better drainage of the kidney. Clearly, noninvasive shock-wave lithotripsy is the treatment of choice when possible for the interventional treatment of stones.