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Kidney & Urinary System

Vesicoureteral Reflux (VUR)

Lea este articulo en EspanolWe’ve all heard of acid reflux — when stomach acids move up into the esophagus and cause a burning sensation — but there can be other types of reflux in the body. When urine (pee) refluxes from the bladder to the kidneys, it’s called vesicoureteral reflux (VUR).

Vesicoureteral (ves-ih-koe-yoo-REE-ter-ul) reflux happens when urine abnormally flows backward from the bladder into the ureters, thin tubes that connect the kidneys to the bladder. If backed-up urine reaches the kidneys, it can lead to infection, scarring, and even long-term kidney damage if left untreated. Fortunately, most kids with VUR don’t have a severe case of it and outgrow it with no long-term complications.

Treatment depends on the severity of the condition. In mild cases, no treatment is necessary. Moderate to severe cases may be treated with antibiotic medicines to prevent infection. In cases where kids have infections and fevers along with the VUR, surgery may be needed.

How the Urinary Tract Works

The urinary tract is made up of two kidneys, two ureters, one bladder, and one urethra. Kidneys are fist-sized, bean-shaped organs in the back that filter excess fluids and waste products from the blood and turn them into urine. The urine then flows out of the kidneys through the ureters, which are long, thin tubes.

The ureters transfer urine to the bladder, a balloon-like organ that stores the urine until it’s emptied during urination. While it’s in the bladder, urine is prevented from flowing back into the ureters by valves in the bladder. During urination, it exits the body through the urethra, a tube at the bottom of the bladder.


Normally, urine flows from the kidneys to the bladder, but defects in one or both ureters can allow it to flow the other way. So can a blockage in the ureters or in the bladder.

When a defect causes the condition, it’s called primary VUR. This is the most common type of VUR affecting kids. If a child is born with primary VUR, it means that a ureter didn’t grow long enough while the baby was in the womb. This can affect the valve where the ureter enters the bladder. If the valve doesn’t shut properly, urine can flow back up the ureters to reach the kidney. Primary VUR is believed to be a genetic condition.

If a blockage in the urinary tract obstructs the flow of urine and causes it to go back into the kidneys, it’s called secondary VUR. Kids with this type of VUR often have reflux in both ureters. Secondary VUR can be caused by nerve damage, infection, or pressure on the ureter from another organ, such as an enlarged prostate.


Most of the time, VUR has no obvious signs or symptoms. It’s often first detected when a child has a urinary tract infection (UTI) with a fever.

Symptoms of a UTI include:

lower tract infection (in the bladder)

  • frequent or urgent need to urinate
  • a burning sensation while urinating
  • blood in the urine, or urine that is cloudy or foul smelling

upper tract infection (in the ureters or kidneys)

  • pain in the side or abdomen
  • fever and chills

As kids get older, untreated VUR, along with any related UTIs, can lead to long-term problems caused by scarring of the kidney. These problems include:

In some cases, VUR may be detected before a baby is born during a routine prenatal ultrasound. An ultrasound uses sound waves to create an image of the baby in the womb. Ultrasounds can sometimes show if a baby has swollen kidneys (hydronephrosis), which could be a sign of VUR.


If your child has symptoms of a UTI, see a doctor right away. To check for VUR, the doctor will do a physical examination and ask you questions about your family medical history. Blood and urine tests may be done to see how well your child’s kidneys are functioning and check for signs of infection or damage to the kidneys.

Doctors can use certain tests to confirm a diagnosis of VUR, such as:

  • An abdominal ultrasound, also called sonography, uses harmless sound waves to create images of the urinary tract and may reveal a defect or blockage that could potentially cause VUR.
  • A voiding cystourethrogram (VCUG) is an X-ray image of the bladder and urethra taken while someone is urinating. In this procedure, a special liquid that can be seen on X-rays is placed in the bladder through a catheter (rubber tube). X-rays are taken of the bladder while it is full and while it is being emptied during urination, and then the images are compared to check for abnormalities.

If VUR is diagnosed, the doctor will grade the condition from I through V based on its severity, and use the grade to decide the best course of treatment. Grade I reflux is the mildest, with urine that backs up only as far as the ureters. Grade V reflux is the most severe and can involve twisting of the ureter and swelling of the kidney.


In many cases, kids with primary VUR outgrow it. As a child gets older, the ureter gets longer and straighter, and the valve where the ureter enters the bladder is able to shut correctly.

VUR that occurs with a UTI needs prompt antibiotic treatment to keep the infection from spreading to the kidneys. Kids who are put on antibiotics should take them for as long as prescribed, even if they start to feel better early on.

In moderate to severe cases of primary VUR with UTIs and fever, the doctor may recommend surgery. The most common type of surgery is ureteral reimplantation, in which one or both ureters are extended further into the bladder to correct the backflow of urine from the bladder to the ureters and kidneys. This type of surgery usually requires kids to spend a few days in the hospital while they recover.

Another surgical procedure, endoscopic injection, involves injecting a special gel into the bladder with the use of a catheter. The gel, placed near the valve at the opening of the ureter, prevents urine from going back into the ureter and helps the valve close properly. Most kids can leave the hospital on the same day that they have this procedure.

To treat a case of secondary VUR, antibiotics are given to fight infections and surgery might be done to remove the blockage causing the reflux.

Moderate to severe VUR, if not treated, can lead to serious health problems down the road. But with prompt treatment, long-term complications and damage to the kidneys can be prevented.

Reviewed by: Robert S. Mathias, MD
Date reviewed: March 2014