Extra-corporeal Shock Wave Lithotripsy (ESWL)
(for stones in kidney, ureter, bile duct and salivary ducts)

Principle
This is also simply called Lithotripsy. High amplitude sound waves generated in a water filled tube are focused on the stone after precisely locating the stone with the use of either X-ray or ultrasound. With repeated application of these shock waves the stone fragments into small pieces which pass through the natural urinary passage.

The Machine
The equipment looks like an X-ray machine. It has 3 components: the couch for patients to lie on, the X-ray or ultrasound to locate the stone and the "shock wave" generator. In some machines these components are separate and in some they are all combined in to a single unit.

SHOCK HEAD OF A LITHOTIRPTOR MACHINE

  

The Treatment
You may need an up to date X-ray before the treatment. There is no need for any form of anaesthesia for the treatment, which is given on a day or out patient basis. Usually patients can drive to the hospital and drive back after treatment. There is no preparation prior to the treatment and you can eat and drink normally. The patient lies on the table and after locating the stone, the shock wave tube is brought into contact with the skin. At the contact point a small amount of water-based "coupling" gel is used.

It is important that you are still during the treatment because body movement moves the stone away from the focal point of the shock waves. The treatment lasts about 45 minutes. During the treatment you will hear the clicking noise of the machine. The intensity of the shock waves will be increased to a level you are able to tolerate.

After Treatment
You may notice some blood in your urine. This is temporary and usually lasts an hour or two. You may get colicky pain while the fragments are passed. Sometimes you may require strong painkillers to control the pain. A further X-ray will be arranged a few days/weeks later to check the fragments.

Serious complications are rare after treatment. Some times the fragments may get "arrested" in the tube that joins kidney to the bladder. If this happens, the fragments may be treated by further lithotripsy but some times a ureteroscopy (see section under ureteroscopy) to deal with the fragments. Very rarely (about one in 500 treatments) bleeding may occur around the kidney (haematoma). This does not require intervention as the blood clot gets absorbed.

How many treatments do I need?
This depends on the size, location and composition of the stone. Small stones fragment completely after one or two treatments. Large or hard stones may need more than two treatments but rarely more than four.

What stones are suitable?
Stones less than 2cm in size in the kidney and those in the ureter (the tube that connects the kidney to the bladder) are suitable for lithotripsy. Stones in the bile duct and some salivary duct stones are also suitable. Stones larger than 2cm, those that do not fragment after lithotripsy are treated by other techniques using telescopes.

Percutaneous Nephrolithotomy (PCNL or Perc)
Stones in the kidney that are not suitable for treatment by lithotripsy or those that do not respond are usually treated by this technique. You will be admitted a day before the operation for antibiotic treatment prior to surgery. Under a general anaesthetic, through a keyhole incision, telescope is passed in to the kidney. The stone is broken up using special probes, which are passed through the telescope. The fragments are either sucked out or removed.

After the operation
You will have a catheter in to the bladder. This will be removed the day after the operation. You will also have a tube into the kidney (called nephrostomy tube). You will have an X-ray on the second day after the operation. If the X-ray shows no residual fragments the nephrostomy tube is clamped. If you do not experience pain or develop a temperature the tube will be removed.

You will stay between 3 to 5 days in the hospital. You will need to stay off work and heavy physical activity for 2 weeks after discharge from the hospital. Thereafter you may engage in light duties. Full physical activity may be resumed by four weeks after the operation.

Complications
Complications are uncommon. Blood transfusion may be needed in 10% of the cases. Very rarely, continuous bleeding may need intervention (this is needed in less than 1% of cases). In about 1% of cases sepsis may occur despite the use of antibiotics.

Ureteroscopy and uretero-pyeloscopy
Ureteroscopy means inspection of ureter (the tube that connects the kidney to the bladder) with a telescope. Uretero-pyeloscopy means inspection of ureter and the drainage system within the kidney with a telescope. Very fine rigid or flexible fibre optic telescopes are used for this procedure which is performed under a general anaesthetic.

These procedures are performed for diagnostic reasons (example: to investigate the cause of blood in the urine) or to fragment stones in the ureter and the kidney. It is also possible to destroy cancerous tumours in the drainage system using laser.

The instruments are passed in to the bladder and then passed up the ureter in to the kidney. Stones are usually fragmented using laser, which is very efficient and safe. Laser fibres can also be passed through flexible fibre optic instruments.

After the operation
You may experience some pain in the kidney area for a few hours. This is usually not severe and is treated with simple painkillers. You may also notice small amount of blood in the urine. This stops in a few hours. It is not unusual to perform the operation as a "day case" but some times an over-night stay may be needed.

Complications
Serious complications are rare. Severe injury to ureter is extremely rare (less than one in 500). Minor injury (like abrasion) may occur occasionally (one in ten cases). In both the cases a plastic tube (called stent) will be left in while the ureter is healing. The stent will be removed after about 3 weeks by passing a telescope in to the bladder under a local anaesthetic.

Formation of stones and their prevention
Stones are formed by the precipitation of minerals in the urine. This occurs if the mineral content in the urine is high or the urine is concentrated due to low urine volume. There are substances in the urine which prevent the stone forming crystals getting together to form a stone. Reduced excretion of these substances (example: citrate) may also produce stones. The most common stone forming minerals are calcium, oxalate and uric acid. Uric acid stones form in urine, which is persistently acidic.

There are many reasons why stones form in the kidney. Some of these are not clearly understood. Environmental factors such as diet play an important role. For example, eating a lot of animal protein (such as meat), food rich in sugars and substances which contain a lot of oxalate (such as chocolate), may increase the excretion of stone forming salts in urine. Chronic dehydration also encourages stone formation.

If you form stones frequently further investigations may be needed to identify any known causative factors. Dietary advice may be tailored to correct any abnormality in the constitution of urine. Occasionally it may be necessary to treat the abnormalities in the composition of urine by medication.