Health Centres - Kidney stones
What are kidney stones?
Kidney stones vary greatly in size. Some are as small as a grain of sand whereas others are so big they fill the entire renal pelvis.
They are not always painful and are sometimes discovered completely by accident after an X-ray or ultrasound examination made for some other reason.
Kidney stones typically occur in formerly healthy men aged between 30 and 50. The male to female ratio for kidney stone disease is 4:1.
The cause of most stones is unknown but they can be associated with a high concentration of calcium in the urine or occasionally in the blood. They can also be caused by dehydration, infection, obstruction of urine and various kidney disorders.
What are the symptoms of kidney stones?
- Kidney stones cause sudden, intense pain. This is usually concentrated on one side of the back but may also move into the stomach or down to the groin where it can result in stabbing pains. The same type of pain may also be caused by haemorrhage or infection in the urinary system.
- Kidney stone attacks can be so painful they cause great distress to the sufferer. The pain is often accompanied by nausea and vomiting.
- They may cause scratches in the lining (mucosa) of the renal pelvis or the ureter. This leads to blood in the urine. There is not always enough to be seen with the naked eye but a diagnostic test can detect it.
- Frequent infections in the urinary system may be a sign of kidney stones.
What should you do if you have an attack?
If you have a kidney stone attack, you will need medical help to ease the pain. If it is 0.5cm or smaller, the attack will usually stop after a few hours when the stones are excreted with your urine. However, if the stone gets stuck on the way out, the process can take several days.
The actual discharge of a kidney stone from the bladder through the urethra is either completely painless or causes a brief stab of pain when urinating.
The doctor may want to see the stones - or calculi. They are obviously difficult to catch but one solution is to try urinating through a sieve.
Will you need to go to hospital?
If the kidney stone is so big that it cannot come out by itself or the pain continues, it will be necessary to go to hospital. An X-ray (urography) or ultrasound examination can show the size of the stone and where it is situated. This is important because it helps doctors decide how, and when, the stone should be removed. If the stone is small and lying close to the bladder, it may be left to pass on its own.
There are many modern methods of removing stones that involve passing a small telescope via the bladder through which a variety of stone disintegrators can be used.
Occasionally, a small opening is made directly into the kidney for large stones. It is very rare nowadays for patients to need open surgery.
What is lithotripsy?
. Lithotripsy uses ultrasound waves to break up kidney stones and gallstones. The treatment is performed in hospital using special equipment and is becoming more and more common. 
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