Kidney stones (or renal stones)

What are kidney stones?

Your kidneys are a filter for your body - removing waste chemicals and excess fluid from your blood by making urine. Most waste dissolves in your urine and passes from your body unnoticed.

Generally, most kidney stones form in the kidney and pass down the ureter (the tube leading from the kidney to the bladder) and out into the bladder, but stones in the ureter (ureteric stones) cause the most symptoms. However, if a stone begins to move out of your kidneys it can be painful. 

The bladder can also form stones, but this happens usually for entirely different reasons, normally related to a degree of retention of urine.

What are the symptoms of kidney stones?

A large stone or a stone that becomes blocked as it is passed may cause symptoms including:

• Blood in Urine (Haematuria)
• Back pain on one or both sides
• Spasms of pain below your ribs, in your abdomen (stomach), sometimes radiating to your groin or genitals
• Frequent urination
• Burning sensation during urination
• Feeling nauseous (sick) or vomiting

If your symptoms increase you should seek medical attention. Your GP may refer you to a urologist for diagnosis and treatment of your kidney stones including endoscopic treatment.

What causes kidney stones?

In children – kidney stones are usually related to different syndromes. Extra minerals are produced in the urine that will not dissolve easily. This is usually picked up in early childhood. In older children, especially girls, urine infections can be associated with particular types of stones.

In adults – this again is related to the production of minerals in the urine that will not easily dissolve. Some people are unprotected from this and will make stones on and off without any real provocation. Most people are protected and will need something in their environment, such as dehydration or something they have eaten such as too much salt or meat, to produce s stone. Stones are very common in men and getting a lot more common in women.

What are the surgical and non-surgical treatments?

• Small asymptomatic stones can be watched, although not all patients can cope with knowing that a stone is inside them.
• Ureteroscopy (URS) and Flexible Ureterorenoscopy (FURS). This is a day case or overnight procedure where stones are removed through a small telescope placed through the water pipes, to either remove the stone or turn it to dust using a laser beam. Pieces removed can be sent for analysis.
• Lithotripsy (ESWL). This is a day case procedure using sound waves to externally break up stones. It has the advantage of being fully external to the patient but may not be suitable for harder stones, or stones in particular parts of the kidney or ureter.
• Percutaneous Nephrolithotomy (PCNL). This is a keyhole operation performed through the side to remove large stones from within the kidney. It can also be used to remove very large stones from the ureter. Recently the technique has moved to be performed with the patient on their back rather than front to allow simultaneous use of telescopes to remove maximum amounts of stones. It has the highest clearance rate for big stones within the kidney but is the largest stone operation and has the longest recovery.
• In patients with more than one episode of stones, or stones in both kidneys, or where a rare type of stone is found, metabolic testing can be undertaken. This is an assessment of the composition of the urine and the blood to look for a cause for the patient’s stones. This may lead to a tailored treatment regime to try and prevent future stones.