Bladder stones - Causes of bladder stones

The most common cause of bladder stones is an inability to completely empty your bladder of urine.

Urine is produced by your kidneys. It is made up of water mixed with waste products that the kidneys remove from your blood. One of the waste products is urea, which is made up of nitrogen and carbon.

If any urine remains in your bladder, the chemicals in urea will stick together and form crystals. Over time, these crystals will harden and form bladder stones.

Some common reasons why people are unable to empty their bladder fully are described below.

Prostate enlargement

The prostate is a small gland only found in men. It is located in the pelvis between the penis and the bladder, and surrounds the tube that carries urine from the bladder to the end of the penis and out of the body (the urethra).

The main function of the prostate is to help the production of semen. In many men, the prostate becomes enlarged as they grow older.

In around one third of men over the age of 50 the prostate gland puts pressure on the urethra and interrupts the normal flow of urine from the bladder.

If treatment for enlarged prostate is given it's unusual for men to develop bladder stones. However, in a minority of men who fail to respond to treatment, there is an increased risk of developing bladder stones.

Read more about prostate enlargement.

Neurogenic bladder

Neurogenic bladder is a condition where nerves that control the bladder are damaged, which means preventing that a person from emptying their bladder fully.

Neurogenic bladder can be the result of:

• serious injury to your spinal column (a long band of nerves that runs from the brain down the centre of the spine) resulting in some degree of paralysis
• conditions that cause damage to the nervous system such as motor neurone disease or spina bifida

Most people with a neurogenic bladder require a catheter to empty their bladder. A catheter is a tube inserted into the urethra and moved up into the bladder. The urine is drained out of the bladder through the catheter. This is known as urinary catheterisation.

However, a catheter, while reasonably effective, is not a perfect substitute for normal bladder control and often leaves a small amount of urine in the bladder. This can lead to the formation of bladder stones.

It is estimated around 1 in 10 people with a neurogenic bladder will develop bladder stones at some point in their life.

Cystocele

A cystocele is a condition that affects women and develops when the wall of the bladder becomes weakened and begins to drop down on to the vagina. This can affect the normal flow of urine out of the bladder.

A cystocele can develop during a period of excessive straining, such as childbirth, chronic constipation or heavy lifting.

Bladder diverticula

Bladder diverticula are pouches that develop in the wall of the bladder. If the diverticula grow to a certain size, it can become difficult for a person to empty their bladder fully.

Bladder diverticula can be present at birth or develop as a complication of infection or prostate enlargement.

Bladder augmentation surgery

There is a type of surgery known as bladder augmentation surgery where a piece of the bowel is removed and attached to the bladder to make it larger.

This can be useful in treating a type of urinary incontinence known as urge incontinence.

Research suggests that around 1 in 20 people who undergo this type of surgery will develop bladder stones.

Diet

Poor diet is a much less common cause of bladder stones in England, but is relatively common in parts of the developing world.

A diet high in fat, sugar or salt but low in vitamin A and vitamin B can increase the risk of bladder stones, especially if a person is also not getting enough fluids to drink (dehydration).

All three of these factors can alter the chemical make up of urine, making the formation of bladder stones more likely.