About kidney stones
The kidneys filter blood and produce urine. Narrow tubes called ureters carry urine from the kidney to the bladder. The bladder stores urine until you are ready to urinate. Another tube called the urethra carries urine from the bladder out of the body. Together, the kidneys, ureters, bladder and urethra are called the urinary tract.
Kidney stones are formed out of crystals found in the urine. In most cases, the crystals are too tiny to be noticed, and pass harmlessly out of the body. However, they can build up inside the kidney and form much larger stones. If a stone becomes large enough to block the flow of urine, it can cause pressure, pain and infection. Depending on their size and position, untreated kidney stones can permanently damage kidney function.
What is lithotripsy?
Lithotripsy is a procedure that uses high-energy sound waves to break down kidney stones into tiny fragments, which can then be flushed out of the body in the urine. The sound waves are pointed at the stones through the skin, but no cuts are made. The procedure is often referred to as extracorporeal shock wave lithotripsy (ESWL).
Lithotripsy is routinely done as an out-patient or day case, without the need for anaesthesia.
Your consultant will explain the benefits and risks of having lithotripsy, and will discuss any alternatives to the treatment.
About the procedure
You will usually be asked to lie on your back on the couch, and an X-ray or ultrasound will be used to pinpoint the exact position of the kidney stone. Once it has been located, some gel will be smeared on your skin to enable good contact with the lithotripter probe. The probe will focus the sound waves precisely onto the stone to break it up. It is best to try and relax during the treatment and avoid making movements, otherwise the kidney stone may move out of focus.
The machine will make a clicking noise as it works but you will probably not feel very much at all to begin with. The intensity of the sound waves will be increased gradually.
Although the sound waves themselves do not hurt, most people feel an unusual and uncomfortable sensation as the stone is broken up. You will be given pain relief to make the procedure more comfortable.Your consultant is present throughout the procedure, so you will be able ask for the treatment to stop if it becomes too uncomfortable.
The treatment usually takes about 20 to 30 minutes. If you have several stones in the same kidney they may all be treated, but only one kidney is treated at a time.
After lithotripsy, you may have some pain and you will be given some painkillers to relieve this. You should drink fluids regularly for 48 hours after your treatment to help flush your kidneys and lower the risk of developing a urinary tract infection. It is quite normal to have small fragments of the broken stone and a little blood in your urine during this time.
Lithotripsy is a commonly performed and generally safe procedure. For most people, the benefits of having this non-surgical treatment for kidney stones are much greater than any disadvantages. However, like all medical procedures, there is an element of risk.
The success of the treatment will depend on the density, size and position of the stone. Your consultant will be experienced, but even so, many lithotripsies are not successfully completed on a single visit and may need to be repeated.
Specific complications of lithotripsy are uncommon, but it is possible to develop a urinary tract infection afterwards, requiring treatment with antibiotics. In rare cases, stone fragments can block the tubes that carry urine from the kidneys to the bladder causing severe pain – you should contact your consultant if you have any pain that doesn’t settle with painkillers.
Very rarely, the kidney tissues can be bruised and damaged after treatment. Usually there are no symptoms, but sometimes bleeding can occur. There is a chance this can permanently affect your kidney function and blood pressure.
The chance of complications depends on the exact type of treatment that you are having and other factors such as your general health. Ask your consultant to explain how any risks apply to you.
Laser stone surgery
A substantial proportion of stones are too large or hard to be treated with lithotripsy and some patients are not suitable. For these we offer the latest laser surgery. This involves a day case procedure during which the stone surgeon passes very thin flexible instruments up to the stone in the kidney, and breaks it up using laser energy. The fragments can then be removed during the operation rather than leaving them to drain, as occurs with lithotripsy. This enables us to analyse the stone thereby helping us prevent further stone formation.
Emergency laser surgery
When a stone becomes lodged in the pipe draining the kidney (ureter) it can cause very severe pain known as renal colic and sometimes, if not treated promptly, kidney damage. We usually treat this by passing a temporary stent which can be uncomfortable. With laser surgery we are often able to remove the stone immediately, without the need for a stent, and our stone surgeons can usually arrange such operations at short notice.
For very large stones - over 2cm - a percutaneous operation is usually required. This involves passing stone breaking instruments into the kidney through a small incision in the back. The operation involves an overnight stay or two.