Conditions and diseases

Bladder infection in children

Symptoms and causes

Symptoms and causes

What is it?

See bladder infection in adults: a bladder infection is a urinary tract infection circumscribed to the bladder and caused by a bacterium. Usually the causative bacterium is E. Coli.

One child in fifty suffers from a urinary tract infection from time to time; girls have it five times as often as boys.

Which factors influence a bladder infection?

  • Holding the urine in the bladder for too long: the longer the urine stays in the bladder, the greater the risk of cystitis (a bladder infection).
  • Insufficient emptying of the bladder when urinating. For example, in those conditions where the bladder muscle is not strong enough to empty the bladder, the residual urine may cause an infection. However, the most common cause of bladder infections in children is constipation: accumulated stools ‘displace’ the bladder, as it were, causing it not to be emptied properly and residual urine to remain in the bladder.
  • Urethra length: girls have a shorter urethra than boys, which makes it easier for bacteria to reach the bladder in girls.
  • Congenital abnormalities: congenital abnormalities can also be a major cause of urinary tract infections. Usually these are vesico-ureteral reflux or a congenital obstruction of the flow of urine from the bladder.
  • Reflux: in both boys and girls, a bladder infection can be caused by the backflow of urine from the bladder to the ureters and kidneys. This is called reflux. By no means are all forms of this condition equally serious. Light forms in babies and toddlers can disappear without treatment.
  • Obstructions to urine flow: e.g. a congenital urethra abnormality (narrowing) that prevents urine from flowing as it normally should.


In children, a bladder infection is not always easy to recognise. Symptoms in young and older children can also differ.

Older children

  • pain while urinating
  • frequent urination
  • small bursts of urine
  • smelly, cloudy urine
  • abdominal pain

Younger children

In younger children, the symptoms of a bladder infection are much less obvious or they do not stand out because they are wearing a nappy. The above symptoms may occur, but are less obvious. Often, the urinary infection only becomes obvious when it has already expanded and the more general, severe symptoms such as fever and chills become apparent.

Toddlers and pre-schoolers
  • eating and drinking poorly
  • listlessness
  • abdominal pain
  • smelly urine
  • irritability
  • fever
  • vomiting
  • not drinking well
  • grey skin tone
  • insufficient weight gain
  • smelly urine
  • irritability
  • fever

Diagnosis and treatment

Diagnosis and treatment

How is the diagnosis determined?

  • Ultrasound imaging of the kidneys: any abnormalities of the kidneys, bladder or urinary tract are detected.
  • Urine analysis: are there any suppurative cells? Urine culture to identify the causative bacterium.
  • Uroflowmetry: how smoothly (or not) does the urine flow?
  • Miction cystogram: an X-ray of the bladder while urinating. It can be checked whether urine flows back from the bladder to the kidneys (vesico-ureteral reflux). The child has to pee while lying down, while pictures are being taken. This is not a pleasant examination, especially as it requires the insertion of a bladder catheter.


If the GP suspects that your child has a bladder infection, he or she will take the following steps:

  • The GP will analyse the urine (count of the infection cells) and have a culture carried out. The culture can show which bacterium caused the bladder infection.
  • He or she will prescribe antibiotics to which most bacteria are susceptible because it can take several days before the results of the urine culture are back. Your child should take these antibiotics for a number of days (usually for about a week).
  • Sometimes, it is necessary to switch antibiotics after a few days if the urine culture shows that the bacteria causing your child's bladder infection is not susceptible to the first round of antibiotics. It is important that your child completes the course of antibiotics.

In the specific case where your child regularly has bladder infections and/or vesico-ureteral reflux, it is sometimes necessary to take a low daily dose of antibiotics preventively, to avoid the recurrence of the bladder infections. This is called ‘antibiotic maintenance treatment’.

An untreated bladder infection can spread to the ureters and kidneys. This can cause kidney pelitis or sepsis (blood poisoning). These are quite serious diseases because they can damage the kidneys, sometimes irreversibly. Timely treatment of a bladder infection can prevent this.

Usually antibiotic treatment is sufficient. In the event of an issue with constipation, this must be addressed. Additional surgical intervention is reserved for children who have been diagnosed with urological anatomical abnormalities (such as reflux, urethral valves or ureter obstruction).

Treatment centres and specialisations

Treatment centres and specialisations

Latest publication date: 14/05/2024
Supervising author: Dr Ameye Filip