Vesicoureteral reflux is when urine flows backward from the bladder into the ureters and kidneys. It boosts the risk of urinary tract infections and kidney damage. It can be treated with observation, antibiotics, or surgery.

Vesicoureteral reflux (VUR) is a condition where urine moves backward out of the bladder and into one or both of the ureters, which are the tubes that connect your bladder to your kidneys. Sometimes, the urine may even reach the kidneys.

This backflow of urine can lead to urinary tract infections (UTIs). In some situations, it can also cause kidney damage.

VUR most often affects children. This article covers what there is to know about VUR in children, including causes and symptoms, as well as how healthcare professionals diagnose and treat the condition.

VUR has two general types: primary VUR and secondary VUR.

In primary VUR, a child is born with changes in one or both ureters.

Typically, the ureters carry urine from your kidneys to your bladder. Your bladder holds the urine until you pee. In children with VUR, however, the valve separating the ureter from the bladder doesn’t seal well. Due to this, urine can exit the bladder and flow back up into the ureters and potentially the kidneys.

In secondary VUR, there’s an issue that prevents urine from effectively leaving the body. This means that it can start to flow back up into the ureters and also sometimes the kidneys.

For example, the lower part of the bladder or the urethra (the tube that allows urine to exit the body) could be blocked or may have become too narrow. Additionally, nerve problems with the muscles in the bladder could also prevent urine release.

VUR is typically more common in children who:

  • are assigned female at birth, though those assigned male at birth tend to present with it earlier
  • are white, compared with Black children, although the reason for this is unknown
  • have a close family member, such as a parent or sibling, who had VUR
  • have known changes in their urinary tract since birth
  • have other medical conditions that can affect the function of the urinary tract, such as overactive bladder, neurogenic bladder, or spina bifida

VUR increases the risk of UTIs. This is because the backflow of urine associated with VUR can carry bacteria further into the urinary tract.

Generally speaking, VUR often doesn’t cause symptoms until a UTI develops. Researchers estimate that about one-third of children with VUR will develop at least one UTI with a fever.

According to the Centers for Disease Control and Prevention (CDC), it can be hard to tell whether a younger child has a UTI because they typically cannot communicate their symptoms to you. The most common sign of a UTI in these children is fever.

UTIs can affect the bladder or the kidneys. Signs and symptoms of a bladder UTI are:

When a UTI affects the kidneys, it’s called pyelonephritis. This can cause additional symptoms like:

Many children with VUR who have UTIs recover without any lasting health concerns.

But VUR can lead to complications that have long-term effects, such as kidney infections and hydronephrosis. Hydronephrosis is when the kidneys swell due to fluid buildup, such as when urine cannot effectively leave the body.

The effects of kidney infections and hydronephrosis can lead to kidney damage. When the kidneys are damaged, they cannot function to filter blood as well.

One 2019 study looked for signs of kidney dysfunction in adults who had VUR as a child. Out of 82 people with available data, researchers found evidence of kidney scarring in 56 people (68.3%).

A 2023 cohort study concluded that children with VUR were at an increased risk of chronic kidney disease.

Another 2022 cohort study of 388 children with VUR found that after a median follow-up of almost 10 years, 0.8% and 1.3% developed high blood pressure or end-stage renal disease (ESRD), respectively. People with ESRD need dialysis or a kidney transplant to stay healthy.

Sometimes VUR in children can go away without treatment. According to the National Kidney Foundation, this typically happens by age 5 years.

The likelihood of VUR self-resolving depends on its grade. VUR is graded on a scale of 1 to 5, based on how far urine backs up in the urinary tract. Grade 1 represents the lowest amount of backflow, whereas Grade 5 is the most severe.

A 2023 research review notes that VUR can spontaneously resolve in about:

  • 80% of grade 1 and 2 VUR
  • 45% of grade 3 VUR
  • less than 10% of grade 4 and 5 VUR

If your child has symptoms of a UTI, it’s best if you take them to see their pediatrician. Many instances of VUR are diagnosed after a child has a UTI that happens with fever.

Not every UTI in children is caused by VUR. However, these infections can cause complications and need to be treated by a doctor.

A pediatrician will first ask about your child’s medical history and perform a physical exam. Then, they will typically use imaging tests to diagnose VUR.

An abdominal ultrasound can help a doctor to see changes or potential problems in the urinary tract. A voiding cystourethrogram (VCUG) is used to help confirm the diagnosis.

VCUG involves the placement of a urinary catheter, as well as the use of a special dye. It then takes X-rays to monitor the filling of the bladder. If a child has VUR, these images can show the backflow of urine into the ureters and kidneys.

Other tests that may be used for diagnosis include:

Once a doctor diagnoses VUR, they can grade it on a scale of 1 to 5, based on how far urine is backing up in the urinary tract. VUR is more likely to go away on its own in children with a lower grade.

Several treatments are available for VUR. Which one is recommended can depend on factors like:

  • your child’s age
  • the grade of their VUR
  • how frequently they have UTIs
  • whether there’s evidence of kidney damage

Observation may be an option for children with low grade VUR. A doctor will monitor their condition periodically with imaging tests to make sure their urinary tract is developing properly.

Some children may be given antibiotics to prevent UTIs while a doctor waits to see if VUR will self-resolve. This is called antimicrobial prophylaxis and is typically used for children with VUR that’s grade 3 to 5.

Surgery is typically used only in severe VUR that causes frequent UTIs and hasn’t gone away on its own. Some surgeries aim to repair the connection between the ureter and the bladder so that urine cannot flow backward.

In another type of surgery, called endoscopic injection, a doctor injects a gel-like substance into the connection between the ureter and the bladder. This creates a bulge in the area that helps prevent backflow of urine

Because VUR often happens due to structural changes in the urinary tract, there’s no surefire way to prevent it. However, if your child has been diagnosed with VUR, you can take steps to prevent UTIs:

  • making sure your child drinks enough liquids
  • encouraging your child not to “hold it” and to pee when they need to
  • promoting appropriate toilet hygiene by teaching your child to wipe front to back after having a bowel movement
  • if your child isn’t yet potty trained, changing their diaper shortly after they have a bowel movement
  • taking steps to address constipation, which can make it harder for a child to empty their bladder and can increase UTI risk

How common is vesicoureteral reflux in children?

VUR is estimated to affect up to 3% of children. Some research has found that it’s been detected in about 31% of children being evaluated for UTIs.

Is surgery required for vesicoureteral reflux in children?

No. Surgery is typically used only when VUR hasn’t gone away on its own, causes frequent UTIs, or has already caused kidney damage. Many children can be treated with observation or preventive antibiotics for VUR.

Are antibiotics safe for children with vesicoureteral reflux?

Yes. Trimethoprim–sulfamethoxazole is an example of an antibiotic that may be used to treat VUR in children.

While this antibiotic is safe, earlier clinical trials did find that long-term use was associated with antibiotic resistance.

VUR is a condition where urine backs up into the ureters and kidneys. It’s more common in children and often results from changes in the structure of the urinary tract that promote the backflow of urine.

Children with VUR are at a higher risk of UTIs and hydronephrosis. These can potentially lead to lasting kidney damage.

In some children, VUR goes away on its own without treatment. Others may need preventive antibiotics or surgery to help with VUR.

VUR is often diagnosed after a child has a UTI with a fever. If your child has signs of a UTI, make an appointment to see their pediatrician.