Urinary tract infections in children - Diagnosis 

Diagnosing UTIs in children 

Children with symptoms of a urinary tract infection (UTI) should always have their urine tested because an accurate diagnosis is important for treatment.

An exception may be made for girls over three years of age who have typical symptoms of cystitis (infection of the bladder), such as urinating more frequently and pain when passing urine.

Urine sample

A urine test is also useful for ruling out other conditions that can cause similar symptoms, such as type 1 diabetes.

If your child has a temperature of 38°C (100.4°F) or above (a fever), and their GP is unable to find an obvious cause, your child’s urine should be tested within 24 hours.

If your child does not have a fever but has other symptoms of a UTI, a urine test will still be required. However, the urine test does not need to be carried out as quickly, and it might be reasonable to wait more than 24 hours to have it done.

In young children, it is very important to make an accurate diagnosis. However, it can be difficult to obtain a clean urine sample from young children because they are often unable to pass urine into a specimen bottle. Also, if the inside rim of the specimen bottle is touched, it will affect the quality of the sample. Therefore, it may be necessary to carry out the test in hospital where health professionals with skill in obtaining a sample are available.

If there is an urgent need to obtain a sample then a small plastic tube, called a catheter, can be placed into your child’s urethra (the tube through which urine passes out of the body). The catheter will be guided up into the bladder and used to drain out a small sample of urine for testing.

This tends to only be used in more serious cases as children can find the experience upsetting.

Further testing

Further testing is usually only required if your child's UTI symptoms are different from common symptoms (atypical). Examples of atypical symptoms include:

  • being seriously ill
  • reduced urine flow
  • a noticeable lump or mass in their abdomen (stomach) or bladder
  • testing which shows the bacteria has spread from their urinary tract to their blood
  • they failed to respond to antibiotic treatment within 48 hours
  • the infection was caused by bacteria other than the Eschericia coli (E. coli) bacteria

Further testing is also required if your child has previously had:

  • two or more upper UTIs
  • one upper UTI, plus one or more lower UTIs
  • three or more lower UTIs

Atypical symptoms and recurring UTIs could be due to underlying problems with your child’s urinary tract infection that will require further investigation.

Tests and procedures commonly used to investigate the urinary tract are described below.

Ultrasound scan

An ultrasound scan is usually the first procedure used to assess the urinary tract. The ultrasound scan uses sound waves to build up a picture of the inside of your child's body.

An ultrasound scan is a useful way of assessing whether there are any obvious abnormalities in your child’s urinary tract, such as an unusually narrow ureter (the tube that runs from the kidneys to the bladder) a bladder stone, or kidney stone.

DMSA Scan

A dimercaptosuccinic acid (DMSA) scan is used to assess the state of the kidney. A DMSA scan is usually carried out six months after an acute atypical UTI (a UTI with unusual symptoms) or after the last episode of a series of recurring UTIs.

A DMSA scan is used to assess whether your child’s kidneys have been damaged, or if there are any abnormalities with the kidneys that are making them vulnerable to recurring UTIs. DMSA is a mildly radioactive substance that shows up on a special camera, known as a gamma camera.

During the procedure, your child will be injected with DMSA. After an hour, the DMSA will build up inside the kidneys. DMSA only attaches itself to healthy tissue, so is a useful method of locating any damaged kidney tissue.

The gamma camera is used to take a series of pictures of your child’s kidneys. It usually takes about 30 minutes to complete the scan. During this time it is important for your child to remain as still as possible, so it may be a good idea to bring their favourite book or toy to help them relax during the scan.

A DMSA scan is not painful because local anaesthetic is used to numb the site of the injection. However, the gamma camera is quite large, so younger children may find the experience upsetting. Explaining exactly what will happen and what to expect before the scan may help reassure your child.

After the scan, the DMSA will pass harmlessly out of your child’s body in their urine. Their urine will be slightly radioactive, but is not harmful to your child or other people. However, as a precaution, it is recommended you wash your hands after changing your child’s nappy, and dispose their nappies in a sealed plastic bag.

Micturating cystourethrogram (MCUG)

Micturating cystourethrogram (MCUG) is a procedure used to study the bladder rather than the kidneys.

MCUG is used to check your child does not have vesicoureteral reflux (a condition where urine leaks back up from the bladder towards the kidneys). As with a DMSA scan, it is important for your child to stay as still as possible during the MCUG procedure. Very young children and babies may need to be wrapped tightly in blankets to help prevent them moving during the procedure.

During MCUG, your child will lie on a bed or treatment table and a catheter will be used to pass a special type of liquid, known as a contrast agent, into their bladder. Like DMSA, the contrast agent shows up very clearly on an X-ray.

An X-ray film will then be taken as the contrast agent is passed out of your child’s bladder, in the same way that their urine passes out.

If the X-ray film shows some of the contrast agent leaking back out of the bladder towards the kidneys, it is likely that your child has vesicoureteral reflux.

Most cases of vesicoureteral reflux resolve without the need for treatment as a child gets older. Your child may be prescribed a long-term course of low-dose antibiotics to help prevent them from developing another UTI, until the condition resolves.

The MCUG procedure is not painful and takes around 30 minutes to complete. However, it is likely your child will feel mild discomfort when the catheter is first inserted into their urethra.

The X-rays will expose your child to a low dose of radiation that is entirely safe. The levels of radiation used are the same as the amount of radiation your child would be exposed to by natural sources (background radiation) over the course of three to six months.

Page last reviewed: 12/06/2012

Next review due: 12/06/2014

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