Understanding the urinary tract
There are two kidneys, one on each side of the abdomen. They make urine which drains down the ureters into the bladder. Urine is stored in the bladder and is passed out through the urethra from time to time when we go to the toilet.
What is a urine infection?
A urine infection is caused by bacteria (germs) that get into the urine. Most urine infections are due to bacteria that normally live in your own bowel. They cause no harm in the bowel but can cause infection if they get into other parts of your body. Some bacteria lie around the back passage (anus) after passing a stool (faeces). These bacteria can sometimes travel to the urethra and into the bladder. Some bacteria thrive in urine and multiply quickly to cause infection.
The infection is commonly just in the bladder (when it is called cystitis), but may travel higher up to affect one or both kidneys as well.
Nearly 1 in 20 boys, and more than 1 in 10 girls, have at least one urine infection by the time they are 16 years old. Children aged under five years are the most commonly affected.
Some terms used by doctors include:
- Urinary tract infection (UTI) – which means a urine infection somewhere in the urinary tract.
- Lower urinary tract infection – which means the infection is confined to the bladder and urethra. This is much the same as cystitis.
- Upper urinary tract infection – the infection affects a kidney and/or ureter.
- Pyelonephritis – this is another term that means infection of a kidney.
- Loin pain – which is a pain in the side of the abdomen, often coming from a kidney.
Does anything increase the risk of developing a urine infection?
In most cases
No. Most urine infections in children are just “one of those things” and there is no underlying problem to account for it.
In some cases
Retaining some urine in the urinary tract may play a part. When we pass urine, the bladder should empty completely. This helps to flush out any bacteria that may have got into the bladder since the last toilet trip. However, some abnormalities or problems that affect the urinary tract can make some urine stay (retain) in the bladder, ureters or kidney. This may allow any bacteria to multiply as urine is a good food for some bacteria. This increases the chance of developing a urine infection. The following are the most common:
If large hard stools collect in the back passage they can press on the bladder. The bladder may then not empty fully when the child passes urine. Treating severe constipation sometimes prevents recurring urine infections.
Dysfunctional elimination syndrome
This is a condition where a child repeatedly holds on to urine and/or stools. That is, they regularly do not fully empty their bladder or bowel when they go to the toilet. There is no physical cause for this (that is, no abnormality in the urinary tract or rectum). The reason why this occurs is often unclear. Stress or emotional problems may be the underlying cause.
An abnormality of the urinary tract
Abnormalities of the urinary tract can cause retention of urine. The most common condition is called vesico-ureteric reflux. This is a problem at the junction where the ureter enters the bladder. In this condition, urine is passed back (refluxes) up the ureter from the bladder from time to time. This should not happen. The urine should only flow downwards out of the bladder when going to the toilet. This condition makes urine infections more likely. Infected urine that refluxes from the bladder back up to the kidneys may also cause kidney infection, scarring, and damage. In some cases this leads to severe kidney damage if urine infections recur frequently. Other rare problems that may be found include kidney stones, or congenital abnormalities of parts of the urinary tract.
Neurological (nerve) or spinal cord disorders
Anything that affects the bladder emptying or sensation. These are rare in children.
Other conditions that increase the risk of a urine infection include having diabetes, and a poorly functioning immune system. For example, children having chemotherapy.
What are the symptoms of a urine infection?
It can be difficult to tell if a child has a urine infection. If they are very young they may not be able to let you know where the problem is. If they are still wearing nappies, you may not notice them passing urine more often.
Young children, toddlers and babies can have various symptoms which may include one or more of:
- Fever (high temperature).
- Vomiting and/or diarrhoea.
- Crying, going off feeds and generally unwell.
- Appearing to be in pain.
- Blood in the urine (uncommon).
- Jaundice (yellowing of the skin).
- Cloudy or smelly urine.
Older children may say that they have pain when they pass urine, and pass urine frequently. If a kidney becomes infected they may also have shivers, and complain of abdominal pain, back pain, or a pain in a side of the abdomen. Bedwetting in a previously dry child is sometimes due to a urine infection. Just being generally unwell may be due to a urine infection.
Note: a urine infection should be suspected in any child who is unwell or has a fever with no other clear cause. This is why a urine test is commonly done when a child is unwell, as a urine infection is important to diagnose and treat promptly.
How is a urine infection confirmed?
A sample of urine is needed to confirm the diagnosis. Urine normally has no bacteria present, or only very few. A urine infection can be confirmed by urine tests that detect bacteria and/or the effects of infection in the urine.
Ideally, the sample of urine should not come into contact with skin or other materials that may contaminate it with other bacteria. Adults and older children can do this by a mid-stream collection of urine. This is not easy to do in young children and babies. The following are ways to get a sample of urine that is not contaminated:
Young children – the usual way is to catch some urine in the specimen bottle whilst they are passing urine. Just be ready with the open bottle as the child passes urine. (Be careful not to touch the open rim of the bottle with your fingers as this may contaminate the specimen with bacteria from your fingers.)
Babies – one method is to place a specially designed absorbent pad in a nappy (supplied by a doctor). Urine is sucked into a syringe from the wet pad. Another method is to use a plastic bag that sticks on to the skin and collects urine. If no pad or plastic bag is available, the following might work. Take the nappy off about one hour after a feed. Tap gently with a finger (about once a second) just above the pubic bone. (This is the bone at the bottom of the stomach above the genitals.) Have ready the open bottle. Quite often, within about five minutes, the baby will pass urine. Try to catch some in the bottle.
If you collect a sample at home, take it to the doctor or clinic as soon as possible after collection. If there is a delay, store the urine sample in the fridge.
What is the treatment of a urine infection in children?
A course of an antibiotic will usually clear the infection within a few days. Give lots to drink to prevent dehydration. Also, give paracetamol to ease any pains and high temperature. Sometimes, for very young babies or for severe infections, antibiotics are given directly into a vein through a drip.
What is the prognosis?
In most cases, this is excellent. Once a urine infection is diagnosed and treated, the infection usually clears away and the child recovers fully. In many cases, a urine infection is a one-off event. However, some children have more than one urine infection and some develop several throughout their childhood (recurring UTIs).
In some cases, an infection can be severe, particularly if a kidney becomes badly infected. This can sometimes be serious, even life-threatening in a minority of cases if treatment is delayed. A bad infection, or repeated infections, of a kidney may also do some permanent damage to the kidney. This could lead to kidney problems or high blood pressure later in life.
When are further tests advised?
Urine infection is common. In most cases, a child with a urine infection will make a full recovery.
Tests are advised in some cases to check on the kidneys and/or bladder. Your doctor will advise if your child needs further tests. It depends on factors such as the child’s age, the severity of the infection, and whether it has happened before. For example:
- Children over the age of six months who have a one-off urine infection which promptly clears with treatment do not usually need any further tests.
- Children with a severe infection, or with an infection with unusual features, may need tests.
- Children who have two or more infections of any severity may need tests.
The tests that are advised may vary depending on local policies and the child’s age. There are various tests (scans, etc) that can check on the structure and function of the urinary tract (the kidneys, ureters, bladder and urethra).
The results of the tests are normal in most cases. However, in some cases, an abnormality such as vesico-ureteric reflux may be detected (described above). Depending on whether an abnormality is detected, and how severe it is, a kidney specialist may advise a regular daily low dose of an antibiotic. This treatment is advised in some cases to prevent further urine infections, with the ultimate aim of preventing damage to the kidneys.
Note: the general rules as to which children should have further tests following a urine infection have been laid out in guidelines from the National Institute for Health and Clinical Excellence (NICE). The section above tries to summarise this guideline. However, this guideline is controversial. Before the publication of this guideline, more children would have usually had tests. For a flavour of the controversy and debate over who needs tests – see the references at the end of this leaflet.
General tips following a urine infection in a child
To help to prevent a further infection in the future:
- Try not to let your child become constipated. A good diet will help here. Ask your doctor for advice on this if you are not sure as to what foods are best to prevent constipation.
- Make sure your child has plenty to drink each day.
Also, see a doctor promptly if you suspect your child has another urine infection. If this is confirmed, remind your doctor that your child has had a previous urine infection. Further tests may be advised.
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