Bacteria can travel up the urethra to the bladder and the kidneys.

The urinary tract is made up of:

• The kidneys
• The bladder
• The tubes that carry urine from the kidneys to the bladder (called the ureters)
• The tube that carries urine from the bladder to the outside (called the urethra).

If bacteria infect a part of the urinary tract, they irritate it. This can lead to symptoms such as discomfort when urinating.¹

Your child's urinary tract is usually free of bacteria.² But the bacteria on the skin around your child's rectum or genitals can sometimes travel up the urethra to the bladder and the kidneys. Girls, for example, can get infected by wiping from back to front after a bowel movement, instead of from front to back.

Some children have an abnormal urinary tract, which can make them more likely to get infections there.¹ One problem is called vesicoureteral reflux, or reflux for short. Normally urine flows from the kidneys to the bladder and then to the outside. But in children with reflux, some urine also flows backward from the bladder toward the kidneys. Your doctor might order tests using ultrasound scans and X-rays to check for reflux. These tests can also tell if your child has a blockage in their urinary tract that might be stopping the flow of urine.

If your child has a weak immune system (the parts of the body that help to fight infection), they may be more at risk of infections of their urinary tract.

A urinary tract infection of the urethra and bladder is sometimes called cystitis. An infection that affects the kidneys is called pyelonephritis.

Kidney infections are much more serious than bladder infections and can cause permanent kidney damage.³ Your child might get a high temperature, vomiting and stomach pain and need hospital treatment right away.