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Vesicoureteral Reflux (VUR)

Medically reviewed by: Jennifer A. Hagerty, DO

What Is Vesicoureteral Reflux?

Vesicoureteral reflux (VUR) is when pee moves backward from the bladder to the kidneys. Normally, pee only flows from the kidneys down to the bladder. In most kids with the condition, it's not serious and they outgrow it 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 flows 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 daytime 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, back, 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 often 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 the bladder doesn’t empty properly, either from a blockage, an abnormal bladder muscle, or injury to the nerves that control peeing.

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 and/or the ureter (the tube that drains the kidneys into the bladder).

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 signs of infection, swelling of the kidney, or a thickened bladder.
  • A voiding cystourethrogram (VCUG) is a test done to specifically look for VUR It's done while the patient pees. A technician fills the bladder with a special liquid, then takes X-rays while it is filling and emptying during peeing.
  • 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?

Kids with mild VUR often don't need treatment. Many kids with primary VUR outgrow it. As a child gets older, the ureter gets longer and straighter, and in time will develop 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 UTIs.


The doctor might talk to you about surgery that can help kids with primary VUR. 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 1–2 days in the hospital while they recover. This surgery is done through an opening under the underwear line or robotically via small incisions on the abdomen.

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 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 cause infections that 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.

Medically reviewed by: Jennifer A. Hagerty, DO
Date reviewed: April 2023