What Is Vesicoureteral Reflux?

Vesicoureteral reflux (VUR) is when pee moves backward from the bladder to the kidneys. Normally, pee flows from the kidneys down to the bladder.

Kids with mild cases of VUR often don't need treatment. Those with more serious symptoms might need to take antibiotics to prevent infection. Kids who have infections and fevers along with the VUR might need surgery. But most kids don't have serious symptoms and outgrow the condition with no lasting problems.

What Happens in Vesicoureteral Reflux?

Thin tubes called ureters (YUR-uh-ters) connect the kidneys to the bladder, and carry urine (pee) to it. The bladder stores the urine until it's emptied when we pee. While urine is in the bladder, it doesn't usually flow back into the ureters. When we pee, urine leaves the body through the urethra (yoo-REE-thruh), a tube at the bottom of the bladder.

In vesicoureteral (ves-ih-koe-yoo-REE-ter-ul) reflux, pee backs up from the bladder into the ureters and sometimes to the kidneys.

What Are the Signs & Symptoms of Vesicoureteral Reflux?

Most kids with VUR don't show signs or symptoms. Often, doctors find the condition because a child has a urinary tract infection (UTI) with a fever.

A UTI lower in the urinary system (in the bladder) can cause:

  • frequent or urgent need to pee
  • bedwetting and pee accidents
  • a burning feeling while peeing
  • blood in the pee, or pee that looks cloudy or smells bad

A UTI higher in the urinary system (in the ureters or kidneys) can cause the same symptoms, as well as:

  • pain in the side or belly
  • fever and chills

What Causes Vesicoureteral Reflux?

Primary VUR is when defects in one or both ureters let pee flow the wrong way. Most kids with VUR have this type. Babies born with primary VUR have a ureter that didn't grow long enough before birth. This can affect where the ureter enters the bladder, letting pee flow back up the ureters to reach the kidney. Primary VUR is thought to be a genetic condition.

Secondary VUR is when a blockage in the urinary tract obstructs the flow of pee and sends it back into the kidneys. Kids with this type often have reflux in both ureters. This can happen because of nerve damage, infection, or pressure on the ureter from another organ.

How Is Vesicoureteral Reflux Diagnosed?

Sometimes, doctors find the condition before a baby is born during a routine prenatal ultrasound. The test might show that the baby has hydronephrosis/urinary tract dilation, which is swelling of the kidneys and along the urinary tract.

If your child has symptoms of a UTI, see a doctor right away. The doctor will do an exam, ask about your family medical history, and might order tests. These can include:

  • Blood tests and urine tests can see how well the kidneys are working and check for signs of infection or kidney damage.
  • An abdominal ultrasound uses sound waves to create images of the urinary tract. These might show a defect or blockage.
  • A voiding cystourethrogram (VCUG) is a test done while the patient pees. A technician fills the bladder with a special liquid, then takes X-rays while it is full and while it empties during peeing. Then, doctors compare the images to check for problems.
  • Contrast-enhanced voiding urosonography (ceVUS). As with VCUG, a catheter is placed and the bladder is filled with a special liquid. But an ultrasound is used instead of X-ray to get an image. This test uses no radiation.

If a child has VUR, the doctor will grade it from I through V. Grade I reflux is the mildest, with pee that backs up only as far as the ureters. Grade V reflux is the most severe.

How Is Vesicoureteral Reflux Treated?

Many kids with primary VUR outgrow it. As a child gets older, the ureter gets longer and straighter, and in time will shut correctly.

Doctors use antibiotics to treat VUR that happens with a UTI. This keeps the infection from spreading to the kidneys. Kids who take antibiotics should take them for as long as prescribed, even if they start to feel better. Some kids will take antibiotics every day as a way to prevent VUR.


The doctor might talk to you about surgery that can help kids with moderate to severe cases of primary VUR with UTIs and fever. The most common type of surgery is ureteral reimplantation. In this procedure, the surgeon extends one or both ureters further into the bladder. This stops pee from flowing backward from the bladder to the ureters and kidneys. Kids who get this surgery usually spend a few days in the hospital while they recover.

Another surgery, endoscopic injection, involves injecting a special gel into the bladder through a thin tube. The surgeon places the gel into the opening of the ureter. This prevents pee from going back into the ureter and helps the ureter close properly. Most kids who have this procedure can leave the hospital on the same day.

Kids with secondary VUR might get antibiotics to fight infections and treatment for the main problem that led to the VUR.

What Else Should I Know?

Untreated VUR can lead to long-term problems. Backed-up pee that reaches the kidneys can scar them, causing:

Always call your doctor if your child has symptoms of a UTI, especially with a fever. Quick treatment of VUR can prevent long-term problems and kidney damage.

Back to Articles

Related Articles

A to Z: Hematuria (Blood in Urine)

Learn more about hematuria (blood in urine) and how it's treated.

Read More

Urinary Tract Infections

A urinary tract infection (UTI) is one of the most common reasons that teens visit a doctor. Learn about the symptoms of UTIs, how they're treated, and more in this article.

Read More


With glomerulonephritis, tiny filtering units in the kidneys stop working properly, causing problems like too much fluid in the body and swelling. Most of the time it can be treated. Find out more.

Read More

Blood in the Urine (Hematuria)

Hematuria is pretty common, and most of the time it's not serious. Find out what causes blood in the urine and what to do about it.

Read More

Your Urinary System

You pee every day, but what makes it happen? Find out in this article for kids about the urinary system.

Read More


Glomerulonephritis happens when tiny filtering units in the kidneys stop working properly. Most cases get better on their own or with treatment.

Read More

Kidney Diseases in Childhood

The kidneys play a critical role in health. When something goes wrong, it could indicate a kidney disease. What are kidney diseases, and how can they be treated?

Read More

Kidneys and Urinary Tract

The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine.

Read More

Recurrent Urinary Tract Infections and Related Conditions

Recurrent urinary tract infections can cause kidney damage if left untreated, especially in kids under age 6. Here's how to recognize the symptom of UTIs and get help for your child.

Read More

Urinary Tract Infections (UTIs)

Urinary tract infections (UTIs) are common in kids. They're easy to treat and usually clear up in a week or so.

Read More

When Your Child Has a Chronic Kidney Disease

Parents of kids who have a chronic kidney disease often worry about what might happen next, how their child feels, and what treatments are likely to be involved. Find answers here.

Read More

Your Kidneys

You need at least one kidney to live. Find out why in this article for kids.

Read More

Kidneys and Urinary Tract

The bean-shaped kidneys, each about the size of a child's fist, are essential to our health. Their most important role is to filter blood and produce urine.

Read More

Ultrasound: Abdomen

Doctors order abdominal ultrasounds when they're concerned about symptoms such as abdominal pain, repeated vomiting, abnormal liver or kidney function tests, or a swollen belly.

Read More

Urine Tests

Is your child having a urine culture or urinalysis performed? Find out why urine tests are performed, and what to expect when the doctor orders them.

Read More

Voiding Cystourethrogram (VCUG)

A VCUG can help evaluate the bladder's size and shape, and look for problems, such as a blockage. It can also show whether pee is moving in the right direction.

Read More

Ultrasound: Renal (Kidneys, Ureters, Bladder)

A renal ultrasound makes images of your child's kidneys, ureters, and bladder. Doctors may order this test if they suspect kidney damage, cysts, tumors, kidney stones, or complications from urinary tract infections.

Read More

How the Body Works Main Page

The human body is an amazing machine. Learn more about it through movies, quizzes, articles, and more.

Read More

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.