Extracorporeal Shock Wave Lithotripsy

Extracorporeal Shock Wave Lithotripsy is a non-invasive alternative to surgery for the treatment of kidney stones. It uses focused, high-energy shock waves to fragment the kidney stones. Following treatment sand-like fragments pass out of the body in the urine over a several week period.

Lithotripsy may be recommended when a kidney stone is too large to pass on its own, or when a stone becomes stuck in the ureter (the tubes that connect the kidneys and bladder).

Lithotripsy is usually not recommended when the kidney stone is greater than 2-3cm in diameter. These stones may need to be surgically removed.

Conditions that may contraindicate the use of lithotripsy include:

• Pregnancy
• Aortic aneurysm
• Bleeding disorders
• Significant obesity
• Severe skeletal abnormalities

The Lithotripsy Bus

A mobile lithotripsy unit operates from several hospitals around New Zealand, from Whangarei to Invercargill, on a regular 28-day circuit. This is a specialised bus equipped with a high tech lithotripter unit and sophisticated medical, theatre and imaging equipment. The bus is staffed by radiographers and nursing staff, with the urologist and anaesthetist being supplied by the hospital the bus is visiting.

Patient files are stored on a computer at the front of the bus. All x-rays are scanned pre and post procedure and patient information and results are collated for comparison and research.

The Lithotripsy Procedure

Lithotripsy is usually a day stay procedure. Admission to hospital will be required prior to the procedure to enable the patient to be fully prepared for the procedure. It is usual for an x-ray to be taken as part of this preparation to check the position of the kidney stone.

Prior to the procedure the patient is not allowed anything to eat or drink for a period of time (usually at least six hours). To ensure the patient remains still during the lithotripsy procedure an anaesthetic is given. This is usually given in the form of intravenous sedation (given through a drip into the hand), though in some cases a general anaesthetic may be recommended.

To allow the shock waves to be transmitted through the skin a rubber pad covered with a special gel is placed against the skin. Using x-ray guidance, the shock waves are focused on the kidney stone and the lithotripsy machine is activated.

The procedure takes approximately one hour, depending on the size and number of kidney stones. Throughout the procedure the patient is constantly monitored by the urologist and an anaesthetist.

If the kidney stone or stone fragments are large, a small tube (stent) may need to be inserted into the ureter prior to lithotripsy. This is positioned via the urethra (the tube from the bladder to the outside) using a telescopic instrument called an endoscope. The stent allows the fragments to pass from the kidney without blocking the ureter. It will be removed in an outpatient clinic at a later date.

After the Procedure

Once awake the patient will be transferred from the bus to the hospital’s recovery room where their recovery is monitored. Once fully awake the patient will return to the ward and will be discharged later that day.

Intravenous fluids may be administered during and immediately after the procedure to help flush out the kidney stone fragments. Once able, the patient will be encouraged to drink plenty of fluid to assist in this process.

Often there is slight bruising around the area where the shock waves have entered the body, causing discomfort. Some discomfort may be also be experienced as the stone fragments pass through the urinary tract. If a stent was inserted there may be some urinary frequency (needing to pass urine frequently) and/or discomfort due to the stent irritating the ureter and bladder.

The degree of discomfort experienced following the procedure will vary between individuals and can be influenced by the size of the residual stone fragments and the duration of the procedure. Pain-relieving medications can help to alleviate any discomfort experienced. Prior to being discharged from hospital, clear recovery and activity guidelines should be given. In some cases a course of antibiotics may be prescribed to help prevent infection.

It is usual for blood to be present in the urine for a few days after the procedure. It is important to inform the urologist promptly if the blood in the urine does not resolve or worsens, if a fever develops, if difficulty with urination is experienced, or there is increasing pain.

Usually work may be resumed the following day, if the person is feeling able.
Follow Up A follow up appointment is usually arranged for four to six weeks after the lithotripsy procedure. An x-ray is taken prior to this appointment to see if the procedure has been successful in clearing the kidney stone.

This fact sheet complements the discussion during your consultation, which will apply your individual circumstances to the above facts.