Vesicoureteral reflux is a condition in which urine flows in the wrong direction, from the bladder back into the ureter. It is most common in infants and young children, but it can affect older children and adults, too.

It can happen if the valve between the ureter and the bladder does not work properly, as the result of a congenital defect or a urinary tract infection (UTI).

Vesicoureteral reflux (VUR) can also cause an infection, because bacteria can develop in the urine. Without treatment, kidney damage may occur.

Studies suggest that between 25 and 40 percent of children who have a UTI also have VUR.

Fast facts on vesicoureteral reflux:

Here are some key points about the vesicoureteral reflux. More detail is in the main article.

  • Vesicoureteral reflux is when urine flows the wrong way, back towards the kidneys.
  • It usually affects infants and young children but it can happen at any age.
  • It is associated with urinary tract infections (UTI), but it is usually caused by a faulty valve that is present from birth.
  • It normally resolves itself, but treatment may be needed to prevent kidney damage.
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In vesicoureteral reflux, a faulty valve causes urine to flow back toward the kidneys.Share on Pinterest
In vesicoureteral reflux, a faulty valve causes urine to flow back toward the kidneys.

Normally, urine is created in the kidneys and filters out through the ureters into the bladder and then out through the urethra. The urine flows in one direction only.

In vesicoureteral reflux (VUR), urine flows in the wrong direction, from the bladder back into the ureters. One in 10 children are thought to have VUR. In most cases, it is due to a faulty valve that was present at birth.

There are two types:

Primary VUR is when an infant is born with a faulty valve between one or both ureters and the bladder. If the ureter is too short, the valve does not close properly, allowing urine to back up, or reflux, from the bladder to the ureter. In severe cases, it can back up to one or both of the kidneys.

Primary VUR may resolve itself in time, as the ureter and valve function improve. Even if it is discovered at birth, no surgical intervention will normally be performed until the infant is at least several months old.

Secondary VUR happens when pressure causes urine to flow backward, usually because of a blockage somewhere in the urinary system. This may be a bladder infection that makes the ureters swell, causing urine to flow back to the kidneys.

Left untreated, VUR can lead to kidney damage and infection, because bacteria can grow in the trapped urine.

Infants and very young children are more likely to have VUR than older children or adults. It is most common in children aged 2 to 3 years. If a parent or sibling has had primary VUR, the chance of a child being born with it is higher.

According to the American Urological Association, VUR is often diagnosed after a UTI, as VUR can predispose a person to developing a UTI.

Symptoms of VUR are variable. In mild reflux, urine backs up just a short distance into the ureter. If reflux is severe, it can result in kidney infections and permanent kidney damage.

A urinary tract infection (UTI) is the most common indication of VUR, but it does not cause it. A UTI may develop without noticeable signs or symptoms, but it is also a common source of fever in infants, both boys and girls.

Without treatment, there is a risk of the infection from a UTI spreading to the kidneys and causing permanent scarring.

Signs and symptoms of a bladder infection or a UTI may be:

  • urgency to urinate
  • a burning sensation or pain when urinating
  • blood in the urine
  • cloudy urine
  • urine with a strong, unpleasant smell
  • dribbling urine, incontinence, and bed-wetting
  • fever and abdominal pain
  • fussiness

These may be less noticeable in infants.

Signs of a kidney infection are:

  • fever
  • pain in the abdomen or back
  • feeling unwell
  • vomiting

Long-term symptoms, if VUR is not treated, include:

  • a palpable abdominal mass, caused by a swollen kidney
  • poor weight gain
  • hypertension, or high blood pressure
  • kidney failure
  • protein in the urine
  • scarring of kidney tissue

An infant may have vomiting, diarrhea, lethargy, and may not be growing normally.

When to see a doctor

Parents or caregivers should consult a doctor if the child has a strong and persistent urge to urinate, experiences a burning sensation when urinating, or has abdominal or flank pain.

Medical advice should be sought if a child Is under 3 months old and has a temperature of 38 degrees Celsius or 100.4 degrees Fahrenheit, or if the child is over 3 months old and has a temperature of 38.9 degrees Celsius or 102 degrees Fahrenheit.

If the child has a fever with no obvious source, a doctor should be consulted. Apart from a UTI, it could be an upper respiratory infection, viral gastroenteritis, or pneumonia.

An infant who is refusing food, eating poorly, is lethargic, difficult to wake up, has inconsolable crying, diarrhea, or vomiting also needs medical attention.

If a child has pain on urinating, an unusual urge to urinate, or a fever, the doctor may carry out some tests.

  • An ultrasound scan may reveal VUR either before or after birth.
  • A urine test can detect a UTI.
  • A radionuclide cystogram (RNC) is a type of nuclear scan that can highlight the shape of the kidneys and show whether they are working properly.
  • A voiding cystourethrogram (VCUG) takes x-ray images of the bladder and urethra while the bladder fills and empties. This can reveal any abnormalities in the structure of the organs or in the flow of urine.

A VCUG involves inserting a catheter through the urethra and into the bladder. A contrast liquid dye that shows up on X-rays is injected through the catheter and into the bladder, filling it up.

Pictures are taken to see whether the urine flows back up to one or both kidneys.

Adverse effects include a slight risk of developing a UTI, discomfort during urination, and an allergic reaction to the dye that may cause bladder spasms. Antibiotics may be given to prevent an infection.

VUR is graded from from grade 1, where urine flows back into the ureter only, to grade 5, where there is severe swelling and twisting of the ureter.

Treatment depends on the patient’s age, overall health and medical history, and the type and severity of the condition.

Primary VUR

The doctor may recommend “watchful waiting,” as the problem often resolves itself. This usually happens as the space where the bladder and the ureter join grows longer with age. A lower grade VUR will normally disappear by the average age of 5 to 6 years.


  • The parents or caregivers should look out for signs of a UTI.
  • They should also ensure the child to use the bathroom regularly to pass both urine and stools.
  • Some drugs can help with bladder control, if necessary.

Antibiotics have been used to prevent infection, but these should be used with care, due to concerns about antibiotic resistance.

In more severe cases, surgery may be necessary to fix the faulty valve to prevent urine from flowing back toward the kidney. In very severe cases, the surgeon may need to remove the scarred ureter and kidney.

The procedure may involve endoscopic, laparoscopic, or open surgery. Endoscopic surgery may be carried out as an outpatient procedure.

A less invasive option is the use of Deflux, a gel-like substance that is injected into the bladder wall. This causes a bulge that makes it harder for urine to flow backward.

Secondary VUR

Treatment for secondary VUR focuses on removing the blockage that is causing the reflux. This may involve antibiotics, surgery, and using a catheter to drain the ureter.

The most serious complication is renal, or kidney, damage.

Kidney scarring can result in permanent kidney damage, if a UTI is left untreated. Renal scarring is also known as reflux nephropathy.

Hypertension, or high blood pressure, may result if the kidneys do not work properly.

Acute kidney failure can occur if toxins build up rapidly in the blood because of a loss of kidney function. In severe cases, the patient may need emergency dialysis.

Chronic kidney disease happens when the kidneys’ function progressively worsens. If a person has chronic kidney disease, it is unlikely that the kidney function will return to normal.

If function falls below 15 percent of normal capacity, the patient has end-stage kidney disease, and they will need either a kidney transplant or regular dialysis.