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NHS Choices Condition

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Urinary incontinence occurs when the normal process of passing urine is interrupted. This can happen for a number of different reasons, which in most cases are related to the different types of urinary incontinence.

How urine is normally passed

Your bladder collects urine from your kidneys and stores it until it is full, stretching like a balloon as it fills up. Normally, your pelvic floor muscles, which surround your urinary opening (urethra), hold it closed and prevent any urine from being passed until you decide to do so.

When your bladder is full, a nerve signal is sent from your bladder to your brain, which lets you know that you need to pass urine. When you get to a toilet, another nerve signal is sent from your brain to your pelvic floor muscles, which relax at the same time as your bladder contracts. This allows urine to be pushed out of your bladder through your urethra.

The various causes of urinary incontinence are described below.

Causes of stress incontinence

Stress incontinence occurs when your pelvic floor muscles have been weakened, and can no longer keep your urethra fully closed. Any sudden extra pressure on your bladder, such as laughing or sneezing, can cause urine to leak out of your urethra.

Your pelvic floor muscles can be weakened by a number of different factors which are outlined below.

  • Pregnancy and childbirth. This can sometimes overstretch and strain your muscles.
  • Menopause. A lack of the hormone, oestrogen, can weaken your muscles.
  • Hysterectomy (removal of the womb). This type of surgery can sometimes damage your muscles.
  • Age. As you get older, your muscles naturally become weaker.
  • Obesity. Being obese can put excess stress on your muscles.

Causes of urge incontinence

Urge incontinence occurs when your bladder contracts too early, often before it is full, and before you have a chance to get to a toilet. It is not known exactly why this happens, but it may be due to mixed up signals between your brain and your bladder.

In most cases, it is not possible to find a cause for urge incontinence and, if this is the case, the problem may be diagnosed as 'overactive bladder syndrome'. However, some specific causes of urge incontinence have been identified, such as those described below.

  • Urine infections, such as cystitis (inflammation of the bladder lining).
  • Conditions that affect the nervous system, such as Parkinson's disease, multiple sclerosis and stroke.
  • An enlarged prostate gland in men. This can irritate your urethra (urinary opening) and lower bladder.

Causes of overflow incontinence

Overflow incontinence is often caused by a blockage or obstruction to your bladder. Your bladder may fill up as usual, but as it is obstructed you will not be able to empty it completely even when you try to.

At the same time, pressure from the urine that is still in your bladder builds up behind the obstruction, causing frequent leaks.

Your bladder can become obstructed by a number of things as outlined below.

  • An enlarged prostate gland in men. This is the most common cause of overflow incontinence.
  • Urinary stones. These are small, hard, stone-like lumps that can form in your bladder.
  • Constipation. A build-up of stools (faeces) can obstruct your bladder.
  • Surgery for urinary incontinence. Sometimes the operation overcorrects the problem.

Causes of total incontinence

Total incontinence occurs when your bladder cannot store any urine at all. It can result in you either passing large amounts of urine constantly, or passing urine periodically, with frequent leaking.

Total incontinence can be caused by a number of things as outlined below.

  • A bladder defect which you were born with.
  • Injury to your spinal cord. This can disrupt the nerve signals between your brain and your bladder.
  • A bladder fistula. This is a small, tunnel-like structure, which can develop between your bladder and a nearby area such as the vagina.

Other causes of urinary incontinence

In some cases, mild urinary incontinence may only be experienced occasionally. If this is the case, your urinary incontinence may be due to one of the following contributory factors.

Certain medicines

Some medicines can disrupt the normal process of storing and passing urine, and increase the amount of urine that you produce. These include diuretics, which are often taken to treat high blood pressure, and muscle relaxants, which you may take if your muscles are very tense.

You may also experience slight urinary incontinence as a result of taking sedatives or sleeping tablets.

Certain drinks

Some drinks, such as those containing alcohol or caffeine, act as diuretics. This means that they cause your bladder to fill up quicker than usual. Drinking alcohol can also make you less aware of when you need to pass urine.

It is also possible for some drinks to irritate your bladder and cause a sudden need to pass urine urgently. These drinks include citrus fruit juices, such as orange juice, and drinks that contain artificial sweeteners.

Urinary tract infections (UTIs)

If bacteria are able to enter your urinary tract through your urethra, you may develop an infection in your bladder, which increases your urge to pass urine.

You may also experience a painful burning sensation when you pass urine, or your urine may smell stronger than usual.


If you smoke, frequent coughing can result in urinary incontinence and make any existing incontinence worse.

Coughing places excess strain on the ring of muscle (sphincter) at the base of your bladder and, over time, constant coughing caused by smoking can severely weaken it.

view information about Incontinence urinary on www.nhs.co.uk »

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