What Causes Incontinence?


After eating or drinking, your kidneys filter the blood to remove water and waste from the body. This filtration process produces urine. The urine travels down smooth tubes called ureters into the bladder.

Normally, you feel the need to use the toilet once the bladder holds 150-250ml of urine. Once ready to urinate, your brain gives the message to your bladder to contract and push urine out. Sphincters and pelvic floor muscles relax enough to allow the bladder to be emptied through the urethra.

Urinary Incontinence is the medical term for bladder weakness, commonly defined as “the unintentional passing of urine”. It can happen to men and women of any age, and affects approximately 5% of the population.

Urinary incontinence occurs when the normal process of storing and passing urine is disrupted.

This can happen for a number of reasons, and certain factors may also increase your chance of developing urinary incontinence.

Some of the possible causes will 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.

What causes Stress Incontinence?

Stress Incontinence occurs when the pelvic floor muscles that support the bladder or urethral sphincter are weakened and therefore the pressure in the bladder becomes too great for the bladder outlet to withstand. The usual cause is weakened pelvic floor muscles and stress incontinence is often related to pregnancy, childbirth, obesity and increasing age (as muscles lose tension).

Your pelvic floor is made up of layers of muscles that form a sling passing from your coccyx (tip of your spine) to your pubic bone. It supports the bladder, bowel and uterus (womb), and forms the floor of the pelvis. Both men and women have a pelvic floor.

Going through the menopause can also increase incidence of Stress Incontinence in women as the reduced oestrogen levels in the body weaken both the pelvic floor and urethral sphincter. The urethra shortens and its lining becomes thinner and these reduce the urethral sphincter’s ability to close tightly.

Men can develop stress incontinence as a result of prostate surgery. The urethral sphincter is close to the top of the prostate and may be slightly injured when the prostate is removed.

Any sudden extra pressure on your bladder, such as laughing or sneezing, can then cause urine to leak out of your urethra.

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What causes Urge Incontinence?

Urge incontinence is caused when the bladder muscle contracts too early and normal control bladder control is reduced. Urge Incontinence is often a symptom of an unstable or overactive bladder. The bladder muscle is technically known as the detrusor muscle, so this condition may also be referred to as detrusor instability.

Normally, the bladder muscle is relaxed as the bladder gradually fills up. Then, when the bladder is roughly half full, your bladder muscle tells the brain and you start to get a feeling of needing to pass urine. However, for people with urge incontinence (overactive bladder), the bladder muscle seems to give the message to the brain that it is actually fuller than it really is. This causes the bladder to  contract too early, giving the feeling that you have to pass urine urgently. 

For the majority of people who experience Urge Incontinence the reason they develop an overactive bladder develops is not known. However the symptoms may get worse during times of stress and the condition may also be influenced by the intake of caffeine (e.g. tea, coffee, cola, etc) and by alcohol.

Some women develop urge incontinence after the menopause and this is thought to be due to the lining of the vagina shrinking (vaginal atrophy) caused by lowering of oestrogen levels.

Urge incontinence may be experienced by people with certain neurological disorders such as Parkinson's disease, Multiple Sclerosis, spinal cord injury or after a stroke.

Similar symptoms to Urge Incontinence may be exhibited if there is irritation in the bladder such as a urinary tract infection (UTI) or stones in the bladder. The bladder may also be irritated if people cut back on fluid intake (often to reduce the need to go to the toiler). Cutting back fluids causes urine to become more concentrated and this may irritate the bladder.

Also going to the toilet too often can make symptoms worse as the bladder becomes used to holding less urine and can then bcome more sensitive and overactive at times when it is stretched a little.

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What causes Mixed Incontinence?

Mixed urinary incontinence is when you have symptoms of both of stress incontinence and urge incontinence. For example, you may leak urine if you cough or sneeze, but also experience the very intense urges to pass urine caused by urge incontinence. The causes of mixed incontinence are those of the specific individual conditions – stress incontinence and urge incontinence. As their causes are different it is not unusual for them to co-exist side by side

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What causes Overflow Incontinence?

Overflow incontinence, sometimes called chronic urinary retention, is usually caused by a blockage or obstruction to the bladder. The bladder will fill up as usual, but as it is obstructed it will not be possible to empty it completely. At the same time, pressure from the urine that is still in the bladder builds up behind the obstruction, causing frequent leaks.

The main reasons that the bladder can become obstructed, causing overflow incontinence are an enlarged prostate (this is very common for men), constipation or bladder stones.  As these are all treatable and also symptoms of other conditions it is important you consult a doctor or health professional if you experience overflow incontinence.

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What causes Faecal (Bowel) Incontinence?

Faecal incontinence is not a condition in itself. It is a symptom of an underlying problem or medical condition therefore it important to seek a medical assessment so the underlying cause can be treated effectively.

There are many possible causes of faecal incontinence and some are more common than others.  Faecal incontinence is usually caused by a physical problem with the parts of the body that control the passage of stools.

The most common cause of faecal incontinence is damage to one or both of the anal sphincter muscles. The external anal sphincter is responsible for delaying bowel emptying once the rectum fills and the urge to empty the bowel is felt.  People with a weak or damaged external anal sphincter muscle typically experience urgency and may pass stools before they are able to reach a toilet.   People with a damaged internal anal sphincter usually experience 'passive soiling', a soft stool or small pellets of stool leak out without the person realising it is happening.

Constipation is another leading common cause of leading cause of faecal (bowel) incontinence. In cases of severe constipation, a large, solid stool can become stuck in the rectum, this is known as faecal impaction. This stool then begins to stretch the muscles of the rectum, weakening them. Watery stools can then leak around the stool and out of the bottom, causing faecal incontinence.

Diarrhoea can be a cause of faecal incontinence as well as a symptom of faecal incontinence. Diarrhoea can be chronic, i.e. on-going and reoccurring, or acute, i.e. sudden and unexpected.

Conditions that can cause recurring diarrhoea include Crohn's disease (a condition that causes inflammation of the digestive system), Irritable Bowel Syndrome (widely referred to as IBS, a condition that causes a range of digestive symptoms, such as diarrhoea and bloating) and Ulcerative Colitis (a condition that causes inflammation of the large bowel). All of these conditions can also cause scarring of the rectum, which in turn can lead to faecal incontinence.

Faecal incontinence can also be caused by a problem with the nerves connecting the brain and the rectum. A nerve problem can mean your body is unaware of stools in your rectum, and may make it difficult for you to control your sphincter muscles. Nerve damage can be related to a wide number of conditions, including diabetes, multiple sclerosis, stroke, spina bifida and spinal cord injury.

People with disorders such as Parkinson's disease and Alzheimer's/Dementia can sometimes develop faecal incontinence that is associated with their illness. Some people may also experience faecal incontinence following gynaecological, prostate or rectal surgery. Chronic laxative abuse may also cause faecal incontinence in the long term.

Some medications like antibiotics can cause loose stools /diarrhoea which may make symptoms worse.

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