Bladder infections

The bladder is part of the urinary system. It is a sac in which urine is collected from the kidneys, and it contracts (squeezes in) when you urinate.

The bladder can be infected with bacteria, viruses, fungi or parasites. Bladder infections can, more rarely, be caused by an infected object coming into contact with the bladder, for example through a catheter that is passed into the bladder, during treatment for another condition.

A bladder infection is a type of urinary tract infection (UTI). One of the main symptoms of a bladder infection is cystitis, which is painful irritation and swelling of the bladder.

See topics on Urinary Tract Infection and Cystitis for further information on these conditions.

One of the most common methods of infection is when bacteria from outside the body travel up the urethra. This is particularly common in women, because there is less distance between the urethra opening and the anus, so bacteria can easily move from one area to the other. This might happen because of poor hygiene or due to vigorous sex. Women are also more likely to have this type of infection because the distance between the urethra opening and the bladder is shorter, so the bacteria do not have as far to travel. (See Cystitis for further information).

Bacteria and viruses can also spread in the blood from other parts of the body, for example if you have an infectious disease such as tuberculosis or diphtheria (both rare in the UK), or a sexually transmitted infection (STI) such as gonorrhoea.

Infections in the kidney can spread through the urinary system to the bladder. In men, an acute bacterial infection of the prostate can both cause and be a cause of bladder infection. The prostate gland is just below the bladder, and infections can pass both ways along the urethra. Viruses such as the herpes virus (which causes genital herpes) can also spread to the bladder and cause infection.

Other causes of bladder infections include parasites such as schistosomiasis (found in some hot countries), and fungi such as candida, which causes thrush. You are more likely to get a fungal infection if your immune system doesn’t work properly, for example if you have diabetes or lupus, or if you have recently had chemotherapy.

You are more likely to have bladder infections if your bladder does not empty fully each time you urinate. You might have a condition called incontinence, when the bladder muscles are either too weak to squeeze all the urine out, or because the nerves around the bladder are damaged and they don’t receive the right messages from the brain about what to do when the bladder is full and empty. This is more common in older men who have an enlarged prostate gland (see Incontinence, urinary). Damage to the nerves can happen during surgery, or because of diabetes or conditions of the nervous system such as multiple sclerosis.

Bladder inflammation (cystitis) can also happen without an infection. It can be caused by exposure to radiation (through radiotherapy) or by a severe allergy. Some people have chronic bladder inflammation, and this syndrome is sometimes called interstitial cystitis. It is not clear whether an infectious agent such as bacteria or viruses causes this, or if it is linked to genetics (inherited characteristics) or another condition.

Symptoms of bladder infection will vary slightly depending on how severe your infection is, and what is causing it.

Common symptoms include:

- Pain, burning or stinging feeling when you pass urine;
- Needing to urinate frequently, but only passing small amounts;
- Dark, cloudy urine, which may smell strongly, or contain blood;
- Tenderness or pain in the lower back, abdomen, or directly above the pubic bone.
In children, other symptoms can include weakness, irritability, reduced appetite and crying.

Your GP or practice nurse will usually require a urine sample, as with most urinary tract infections, to diagnose your infection.

You may be asked for a midstream specimen of urine, which is when you begin urinating into the toilet, then stop. Then you urinate a little into the sterile sample pot, and finally finish off in the toilet. It can be difficult to get a midstream sample from children, so ask your GP or nurse for advice.

If the cause of your infection is a straightforward bacterial infection, further test are not usually needed. However, if you have repeated infections, you may need tests to see whether there is an underlying problem such as damage to your bladder, or whether you are simply prone to cystitis. You might need an ultrasound scan to examine your bladder, or blood tests to see if you have infections in other parts of your body. Magnetic resonance imaging might be used to see if you have kidney stones or a tumour, which might be causing symptoms.

In men, if you have a bladder infection you may be examined to see if you have a prostate problem (see Prostate disease for further information).

If the cause of your bladder problem is not clear, you might have cystoscopy. This enables doctors to look for scars, sores, and other problems inside the bladder, and is usually done under general or epidural anaesthetic. You might also need a bladder biopsy.

Treatment depends on the cause of the bladder infection.

Mild bacterial infections such as cystitis will usually go away on their own, in 2-4 days. You should visit your GP if it does not. You can take over-the-counter painkillers such as paracetamol to ease any pain (but always read dosage instructions on the packet).

If you have a bacterial infection, your GP may prescribe a short course of antibiotics. If you have repeated attacks of cystitis, or a severe infection, you may be prescribed a longer course of antibiotics.

Drinking plenty of water is often recommended as a treatment for cystitis. There is no evidence that this is helpful, although drinking at least two litres of fresh water per day is generally good for health.

Taking sodium citrate or potassium citrate may be helpful in easing some of the symptoms. These are available from your pharmacist without a prescription.

If your infection has been spread to the bladder from another part of the body or is a side effect of another condition such as gonorrhoea, this should also be treated appropriately. For example, gonorrhoea is treated with antibiotic tablets or injections, and the parasitic infection schistosomiasis is treated with anti-worm drugs called anthelmintics. Bladder infections caused by the herpes virus are usually treated with antiviral drugs such as acyclovir. Fungal infections are usually treated with antifungal tablets such as flucytosine, or it might be necessary to wash the bladder out using a liquid containing antifungals such as amphotericin.

Certain types of bladder infection, such as parasitic infection with schistosomiasis, may make you more likely to have bladder cancer.

Prostate and kidney infections can also result from bladder infections, spreading through the urinary system.

It is not possible to prevent all bladder infections but there are some measures you can take to reduce the likelihood of getting them:

- Always empty your bladder fully when you urinate;
- Drink lots of water to flush your bladder out regularly;
- Make sure you practise good toilet hygiene, for example wiping front to back in women, and keep your genital area clean and dry;
- If you have a catheter, make sure you follow all the instructions and hygiene measures advised by your nurse or doctor, and ask for advice if you are not sure;
- To avoid sexually transmitted infections such as gonorrhoea, always use condoms when you have sex, particularly with new partners;
- Empty your bladder regularly and don’t ‘hang on’ for long periods, to help prevent urinary tract infections. NHSDEC07