Urology Health - What is Vesicoureteral Reflux?


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What is Vesicoureteral Reflux?

Normally, urine flows one way, down from the kidneys, through tubes called ureters, to the bladder. But what happens when urine flows from the bladder back into the ureters? This is called vesicoureteral reflux.

With vesicoureteral reflux, urine flows backward from the bladder, up the ureter to the kidney. It may happen in one or both ureters. When the "flap valve" doesn’t work and lets urine flow backward, bacteria from the bladder can enter the kidney. This may cause a kidney infection that can cause kidney damage.

When the flow of urine back up the ureters is more severe, the ureters and kidneys become large and twisted. More severe reflux is tied to a greater risk of kidney damage if there is an infection present.

How Does the Urinary Tract Work?

Urine is made when blood is filtered by the kidneys. Urine flows from the kidneys down through the ureters and into the bladder. This one-way flow is usually maintained by a “flap valve” where the ureter joins the bladder. This keeps urine from backing up into the kidney.


VUR can lead to serious issues; it often does not cause pain or make it hard to pass urine.


The exact percentage of children with VUR is unknown. However estimates are that VUR occurs in about 10 of every 100 healthy children. It is not contagious. In most children, reflux is the result of a birth defect. There is an shorter than normal attachment between the ureter and bladder, with a short flap valve that doesn’t work. In some children an infrequent voiding pattern may cause reflux.

In many cases, reflux appears to be passed down (inherited). About 1 in 3 sisters and brothers of children with reflux also have this health problem. Also, if a mother has been treated for reflux, as many as half of her children may also have reflux.

VUR and Infections

VUR is most often found after a child has a UTI. A urinary tract infection is a bacterial infection of the urinary tract. It may involve the kidney, the bladder or both. In fact, about 1 of every 3 children with a UTI is found to have vesicoureteral reflux.

Some signs of a kidney infection are:

  • fever
  • pain in the belly or lower back
  • feeling ill in general
  • feeling sick to the stomach
  • throwing up

Signs of a bladder infection are:

  • painful and frequent voiding
  • an urgent need to pass urine
  • wetting (lack of urinary control)

The signs of UTIs in babies may not be as clear, but may involve:

  • fever
  • fussiness
  • throwing up
  • diarrhea
  • poor weight gain

Older children can also have UTIs without any clear signs.

The bacteria that cause UTIs are often from the child’s feces. Even with clean habits, bacteria may gather in the groin, and enter the urethra and bladder. If the child has VUR, the bacteria may travel to the kidney(s) and result in infection.

Though VUR is most often found after a child has been treated for a UTI, it is key to remember that VUR by itself does not cause UTI and UTI does not cause reflux.


In some cases VUR is found in testing before birth. Most often it is found in children when they are 2 to 3 years old. But it may be seen at any age, even in babies or older children. About 3 out of every 4 children treated for reflux are girls. VUR is most often found when a child has a UTI.

Reflux is found with a test called a voiding cystourethrogram (VCUG), which is an X-ray of the bladder. It takes about 15 to 20 minutes, and involves:

  • Placing a catheter (a thin plastic tube) in the urethra
  • Injecting fluid with an X-ray dye through the tube until the bladder is full
  • Asking the child to pass urine
  • Taking pictures of the bladder to see if the dye goes backward up to 1 or both kidneys
  • Sometimes adding a small amount of radioactive tracer in the fluid and using a special camera

Infection linked to using a catheter for these tests occurs in a few children, so the urologist may suggest using antibiotics before and after the test.

Ways to ease pain and worry about using the catheter should be discussed with the doctor. Some children become upset and need to be held during the test. In some medical centers the study can be done with light sedation. Using general anesthesia may lead to incomplete test results because the doctor needs to see whether there is reflux when the child is voiding.

If reflux is found, further imaging tests may be done to check how well the kidneys are working and to look for kidney damage. In some cases, ultrasound of the kidneys and bladder may be done to check the size of the kidneys.

How is VUR Measured?

The doctor looks at an X-ray of the urinary tract to find out the reflux grade. This shows how much urine is flowing back into the ureters and kidneys, and helps the doctor decide what type of care is best.

In children with reflux and UTI, kidney damage may occur. Higher grades of reflux are linked to a greater risk of kidney damage.

The most common system of grading reflux (the International Study Classification) includes 5 grades:

  • Grade I: urine reflux into the ureter only
  • Grade II: urine reflux into the ureter and the renal pelvis (where the ureter meets the kidney), without distention (swelling with fluid, or hydronephrosis)
  • Grade III: reflux into the ureter and the renal pelvis, causing mild swelling
  • Grade IV: results in moderate swelling
  • Grade V: results in severe swelling and twisting of the ureter

Risk of Kidney Damage

Children with reflux undergo a careful urological history and physical exam to find out the level of risk for kidney damage. This helps in the decision about the type of treatment.

The doctor will ask about important information, such as:

  • Whether the child is passing urine regularly
  • Whether the child has normal bladder control during the day
  • Whether the child empties his or her bladder fully
  • Whether the child has constipation

Many children with reflux have "dysfunctional elimination syndrome" or "bowel-bladder dysfunction." This happens when the child does not void often or fully. These children have a greater risk of kidney infection with reflux. On the other hand, in children with normal bladder control, normal kidneys and lower grades of reflux, the risk of kidney infection seems lower.


Medical or Non-Surgical Treatment

Often reflux will go away with time. The lower the grade of reflux, the more likely it is to go away. The average age for this to happen is 5 to 6 years. The goal of medical or non-surgical treatment is to prevent UTI and kidney damage while the child grows. Reflux improves in many children because the junction between the bladder and the ureter gets longer with age.

This treatment involves:

  • Encouraging the child to use the restroom regularly
  • Checking that the child has regular stools bowel training
  • Prescribing low doses of a preventive antibiotic to avoid a UTI
  • Trying other drugs if the child is having trouble with bladder control

The child is seen in the office from time to time for a physical exam and urine is checked for infection. X-ray studies of the bladder and/or kidneys can also be done to check the status of the reflux and growth of the kidneys.


The goal of surgery is to cure reflux and avoid the risks of continued reflux. Surgery is most often done using general anesthesia. The surgeon makes a cut in the lower belly, and fixes the flap-valve attachment of the ureter to the bladder. This should prevent reflux from occurring. No artificial material is used and many techniques work well.

In endoscopic surgery (less invasive), the surgeon inserts a tool called a cystoscope into the urethral opening to see inside the bladder. A substance is then injected into the area where the ureter enters the bladder to try to fix the reflux. This requires the use of general anesthesia but in most cases it can be done on an outpatient basis. The rate of success compared to regular surgery depends on the particular case.

If surgery is necessary, the urologist will discuss the different options with the family.

After Treatment

After surgery the patient is generally in the hospital for a few days. A catheter is often used to drain the bladder during this time.

Several months after the operation an X-ray is done to make sure that the operation was successful. Once the reflux is corrected, it is not likely to come back.

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