Lithotripsy

"Lithos" -- Greek for "stone" "Tripsis" -- Greek for "breaking"

Lithotripsy is a non-invasive procedure that helps your body rid itself of kidney stones with a minimum of pain.

Lithotripter

Lithotripsy is a method of crushing a kidney stone while it's still inside your body, without any surgical incisions. During Lithotripsy, carefully directed shock waves pass harmlessly through your body and hit the stone, causing it to crumble into sand-like particles. The stones must be clearly viewed by the x-ray monitor so the shock waves can be targeted accurately. If anatomical abnormalities prevent this, other methods of stone removal may have to be considered. Through examination, x-ray and other tests, the doctor can decide whether this is the best treatment for the patient. In some cases, Lithotripsy may be combined with other forms of treatment.

There are several types of Lithotripsy:

Extracorporeal shock wave lithotripsy
Shock wave lithotripsy
Laser lithotripsy
Percutaneous lithotripsy
Endoscopic lithotripsy

While lying down on a water cushion, a rapid series of high-energy shock waves pass through the water to the stone. Without injury to the body, the stone is then shattered into very fine sand. These particles can then pass easily out of your urinary tract.

In contrast, other methods of stone removal require open surgery (surgical nephrotomy); extraction of the stone through a puncture in the side of the patient (Percutaneous extraction); or the insertion of a ureteroscope via the urethra with subsequent stone fragmentation and removal by mechanical means. All invasive procedures carry a higher risk of infection complications than non-invasive procedures such as lithotripsy.

Shockwave

Occasionally, if the stone blocks the flow of urine (an obstructive calculus) the patient experiences severe pain (renal colic). This pain can be controlled by introducing a stent into the ureter. The stent is basically a tube, which is placed in the ureter and allows the urine to drain past the obstruction. The stent may be left in after lithotripsy in case of obstruction due to fragments becoming lodged in the ureter.

A shock wave is characterised by a very rapid pressure increase in the transmission medium and is quite different from Ultrasound. The shock waves are transmitted through the patient's skin and pass harmlessly through the patient's soft tissue. The shock wave passes through the kidney and strikes the stone. At the stone boundary, energy is lost, and this causes small cracks to form on the edge of the stone. The same effect occurs when the shock wave exits the stone. With successive shocks, the cracks open up, and in turn, smaller cracks form within the large cracks. Eventually, the stone is reduced to small particles, which are then flushed out of the kidneys or ureter naturally during urination.

The process generally takes about 1 hour during which up to 8,000 shocks are administered. The patient will experience some discomfort during the treatment depending on the patient's pain tolerance. Analgesics may be administered to make the patient more comfortable. There are two ways to remove stones using shock wave treatment. In one method, the patient is placed in a tub of lukewarm water. Using x-rays or ultrasound to pinpoint the location of the stones, the body is positioned so that the stones are targeted precisely. In the second, more common method, the patient lies on top of a soft cushion or membrane through which the waves pass. About 1-2 thousand shock waves are needed to crush the stones. The complete treatment takes about 45 to 60 minutes.

The main advantage of this treatment is that many patients may be treated for kidney stones without surgery. As a result, complications, hospital stays, costs and recovery time are reduced. Unfortunately, not all types of kidney stones can be treated this way. In addition, stone fragments are occasionally left in the body and additional treatments are needed.

Shockwave Comparison

Anaesthesia, either local, regional or general is used to help the patient remain still and to reduce any discomfort. Usually, patients are hospitalised for a day or two. In some cases, lithotripsy may be done on an outpatient basis. After treatment is complete, the patient can move about almost at once. Many people can fully resume daily activities within one to two days. Special diets are not required, but drinking plenty of water helps the stone fragments pass. Some pain may occur when the fragments pass, which begins soon after treatment and may last for up to four to eight weeks. Oral pain medication and drinking lots of water will help relieve symptoms. Most patients have some blood in the urine for a few days.

In those patients who are thought to be good candidates for this treatment, about 70 to 90 percent are found to be free of stones within three months of treatment. The highest success rates seem to be in those patients with mobile stones that are located in the upper portions of the urinary tract (kidney and upper ureter). After treatment, some patients may still have stone fragments that are too large to be passed. These can be treated again if symptoms persist.

About 90 percent of stones pass through the urinary system without treatment. In cases where this does not occur, treatment to remove stones may be needed. Some stones may be dissolved by medicines.

In other cases, one of the following methods of stone removal may be needed:

Percutaneous Stone Removal

When stones are quite large (more than 2 cm) or in a location that does not allow effective lithotripsy, a technique called percutaneous stone removal may be used. In this method, the surgeon makes a small incision in the back and creates a tunnel directly into the kidney. A tube is inserted and the stone is removed through this tube.

Ureteroscopic Stone Removal

For stones found in the lower part of the urinary tract, the doctor may pass a ureteroscope (a hollow tube-like device) up into the bladder and ureter. A basket-like device may be passed through the tube to grasp and withdraw the stone.