Kidney stones form when salts or minerals normally found in urine become solid crystals (crystallise) inside the kidney. In most cases, the crystals are too tiny to be noticed, and pass harmlessly out of your body. However, they can build up inside your kidney and form much larger stones.
Sometimes the stone may begin to move out of your kidney and down the ureter towards the bladder. On its way down the ureter it may get stuck intermittently, causing “renal colic“, a severe sharp intermittent pain.
If the stone does not pass through the kidney, it can grow into a large stone that will be too large to pass out of the kidney down the ureter. These stones may cause severe pain or infection in the urine. A smaller stone may just sit in the kidney and not cause any symptoms. Often these stones are found after a scan for something else.
Kidney stones are diagnosed using an ultrasound or X-ray, and further tests may include a CT scan, to see the exact size, location and number of stones. Blood tests to look at kidney function and to see if there is an underlying reason for developing stones, and urine tests to look for infection will also need to be done.
Depending on where they are located and their size, kidney stones can be treated by a number of different methods.
This is the most common method of dealing with small kidney stones. The kidney stone is located using X-ray imaging or ultrasound scanning. While you are lying down, a machine called a lithotriptor sends targeted shock waves to break up the kidney stone into pieces small enough to be passed naturally. Sometimes you will experience pain as the stone fragments pass. This procedure is usually performed using standard pain killing tablets as a daycase, without the need for a general anaesthetic.
If a stone is lodged in the ureter, a narrow instrument called a ureteroscope can be passed up through the bladder and into the ureter. The stone is captured and removed, or broken up using a holmium laser. For smaller stones in the kidney that have not responded to ESWL a small flexible ureteroscope can be used, and a laser passed up this to break the stone into small pieces. These procedures are usually done under a general anaesthetic, and often can be done as a daycase.
A stone lodged in the ureter seen at operation: watch a video of ureteroscopy and laser stone fragmentation.
Please click here for more information about the use of the holmium laser to break up kidney stones.
Large stones often need to be surgically removed from the kidney. The kidney surgeon makes a small cut in your back and uses a telescopic instrument called a nephroscope to pull the stone out or break it up with shock waves or an ultrasound machine. This procedure is done under a general anaesthetic, and you will usually need to be in hospital for a minimum of two nights after the operation.
All of these treatments are available through Cambridge Urology Partnership.
Once a stone has been treated it is important to try and prevent the development of further stones. This can be done in the form of dietary advice, and for all patients some basic tests to see why they made a kidney stone should be performed.
Read our information leaflet on dietary advice for stone formers.
Cambridge Urology Partnership is delighted to be one of the only clinics in the country to offer StoneScreen. StoneScreen is a unique and comprehensive programme which investigates the causes of kidney stones. Kidney stones form for many different and often subtle reasons. Using data from over 3000 patients and 40 years’ experience, StoneScreen have developed a system using lifestyle and dietary information, combined with the results of urinary, blood and stone tests to calculate a personalised risk profile. StoneScreenuses this system to provide individualised advice to kidney stone formers. StoneScreen is the most comprehensive scheme available in the UK for assessing all the potential risk factors that lead to stone-formation, and Cambridge Urology Partnership are one of the only clinics in the country to offer this. For more information see their website www.stonescreen.co.uk.
In a select group of patients a more thorough check of their blood and urine “biochemistry” or make-up is advised, to diagnose the cause of stone formation. This will usually involve collection of two 24 hour urine collections. It is very important that all the urine that you pass is collected, and that you collect the urine for a full 24 hour period on both occasions. You do not need to do the collection on consecutive days, however. On the day that you plan to start your urine collection, pass urine into the toilet when you wake up, and then flush it away. Note down the time. Then every time you pass urine for the rest of the day, including the first void of the following day (at the same time you noted down the previous day), void into the collection bottle. If you are unable to drop off your collection that day, then please keep it in a cool dark place until you are able drop it off for analysis. Repeat the procedure for the second collection. Please make sure that your name is written on the collection bottle, as well as the date of collection, and that the request form in enclosed with the collection bottle. Once we have the results of the collection, we will be in contact with you.