Urinary incontinence occurs when the normal process of storing and passing urine is disrupted. This can happen for a number of reasons.
Certain factors may also increase your chance of developing urinary incontinence.
Some of the possible causes lead to short-term urinary incontinence, while others may cause a long-term problem. If the cause can be treated, this may cure your incontinence.
Causes of stress incontinence
Stress incontinence occurs when the pressure inside your bladder as it fills with urine becomes greater than the strength of your urethra to stay closed. The urethra is the tube urine passes through out of your body.
Any sudden extra pressure on your bladder, such as laughing or sneezing, can then cause urine to leak out of your urethra.
Your urethra may not be able to stay closed if the muscles in your pelvis (pelvic floor muscles) are weak or damaged, or your urethral sphincter – the ring of muscle that keeps the urethra closed – is damaged.
These problems may be caused by:
- damage during childbirth – particularly if the child was born vaginally, rather than by caesarean section
- increased pressure on your tummy – for example, because you are pregnant or obese
- damage to the bladder or nearby area during surgery – such as the removal of the womb (hysterectomy) in women, or removal of the prostate gland in men
- neurological conditions – that affect the brain and spinal cord, such as Parkinson's disease or multiple sclerosis
- certain connective tissue disorders – such as Ehlers-Danlos syndrome
- certain medications
Causes of urge incontinence
The urgent and frequent need to pass urine can be caused by a problem with the detrusor muscles in the walls of the bladder.
The detrusor muscles relax to allow the bladder to fill with urine, then contract when you go to the toilet to let the urine out.
Sometimes the detrusor muscles contract too often, creating an urgent need to go to the toilet. This is known as having an overactive bladder.
The reason your detrusor muscles contract too often may not be clear, but possible causes include:
- drinking too much alcohol or caffeine
- poor fluid intake – this can cause strong, concentrated urine to collect in your bladder, which can irritate the bladder and cause symptoms of overactivity
- conditions affecting the lower urinary tract (urethra and bladder) – such as urinary tract infections (UTIs) or tumours in the bladder
- neurological conditions
- certain medications
Causes of overflow incontinence
Overflow incontinence, also called chronic urinary retention, is often caused by a blockage or obstruction of your bladder.
Your bladder may fill up as usual, but as it's obstructed you won't be able to empty it completely, even when you try.
At the same time, pressure from the urine that's still in your bladder builds up behind the obstruction, causing frequent leaks.
Your bladder can become obstructed as a result of:
Overflow incontinence may also be caused by your detrusor muscles not fully contracting, which means your bladder doesn't completely empty when you go to the toilet. As a result, the bladder becomes stretched.
Your detrusor muscles may not fully contract if:
- there's damage to your nerves – for example, as a result of surgery to part of your bowel or a spinal cord injury
- you're taking certain medications
Causes of total incontinence
Total incontinence occurs when your bladder can't store any urine at all. It can result in you either passing large amounts of urine constantly, or passing urine occasionally with frequent leaking.
Total incontinence can be caused by:
- a problem with your bladder from birth
- injury to your spinal cord – this can disrupt the nerve signals between your brain and your bladder
- a bladder fistula – a small, tunnel-like hole that can form between the bladder and a nearby area, such as the vagina, in women
Medications that may cause incontinence
Some medicines can disrupt the normal process of storing and passing urine, or increase the amount of urine you produce.
Stopping these medications, if advised to do so by a doctor, may help resolve your incontinence.
In addition to the causes mentioned above, some things can increase your risk of developing urinary incontinence without directly being the cause of the problem. These are known as risk factors.
Some of the main risk factors for urinary incontinence include:
- family history – there may be a genetic link to urinary incontinence, so you may be more at risk if other people in your family have experienced the problem
- increasing age – urinary incontinence becomes more common as you reach middle age, and is particularly common in people over the age of 80
- having lower urinary tract symptoms (LUTS) – a range of symptoms that affect the bladder and urethra; read about the symptoms of urinary incontinence for more information