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Rady Children's Specialists

Vesicoureteral Reflux

Vesicoureteral reflux (VUR) is the backup of urine from the bladder (organ that stores urine) into the ureter (tube that carries urine from the kidney to the bladder) during urination. VUR may result in urine reflux into the renal pelvis, causing distention (hydronephrosis) and kidney damage. In children, this condition is usually caused by congenital (present at birth) abnormalities and is often diagnosed during prenatal ultrasound.


There are two types of VUR: primary and secondary. Primary reflux is caused by a congenital (present at birth) abnormality, and secondary reflux is caused by a urinary tract infection (UTI) or an obstruction in the urinary tract.

Reflux is graded according to its severity:

  • Grade I results in urine reflux into the ureter only.
  • Grade II results in urine reflux into the ureter and the renal pelvis, without distention (hydronephrosis).
  • Grade III results in urine reflux into the ureter and the renal pelvis, causing mild hydronephrosis.
  • Grade IV results in moderate hydronephrosis.
  • Grade V results in severe hydronephrosis and twisting of the ureter.

Incidence and Prevalence

VUR is diagnosed in 17–37% of prenatal ultrasounds. The condition is more prevalent in females and in children who have red hair. One-third of UTIs in children are caused by vesicoureteral reflux.

Causes and Risk Factors

Undetermined genetic risk factors may affect the development of VUR. About 34% of patients who have the condition have siblings who are also affected. Siblings of patients with VUR are routinely tested for the condition, even when symptoms are not present.

The most common cause for primary reflux in children is an abnormality in the section of the ureter that enters the bladder (called the intravesical ureter). The intravesical ureter may not be long enough to enable the ureter to close sufficiently to prevent urine reflux, or the ureter may be inserted abnormally into the bladder. This condition often resolves as the child grows and the ureter lengthens. Other causes of primary reflux include abnormalities in detrusor muscle tissue of the bladder, abnormalities in the location of the urethral opening (e.g., hypospadias), and abnormalities in the shape of the urethral opening.

Secondary reflux is often caused by a UTI (e.g., cystitis) that results in inflammation and swelling of the ureter. UTI may cause vesicoureteral reflux or vesicoureteral reflux may promote the growth of bacteria in the urinary tract, causing UTI. Secondary reflux may also be caused by urinary tract abnormalities (e.g., narrowing, or stricture, of the ureter; duplicated ureters; ureterocele) and obstructions (e.g., UPJ obstruction, stones, tumor).

Signs and Symptoms

The most common symptom of VUR is urinary tract infection (UTI). Other symptoms might include the following:

Bedwetting (nocturnal enuresis)

• Distention in the abdomen (caused by hydronephrosis)

• Failure to thrive

• High blood pressure (hypertension; caused by kidney damage)

Hydronephrosis (collection of urine in the renal pelvis)

• Nausea and vomiting

• Protein in the urine (proteinuria)


Untreated VUR provides access for bacteria to enter the kidneys and may result in kidney infection (pyelonephritis), kidney damage, and progressive renal failure.


VUR is commonly diagnosed during infancy or childhood as a result of a urinary tract infection (UTI). UTI is diagnosed using urinalysis and urine culture. VUR that causes hydronephrosis is often diagnosed during prenatal ultrasound. A cystogram (also called cystourethrogram) and a voiding cystourethrogram (VCUG) are performed to determine if an abnormality in the urinary tract is causing reflux. In these procedures, a contrast dye is instilled into the bladder through a catheter and a series of X-rays are taken.

Other diagnostic tests used to diagnose VUR include the following:

• Bladder ultrasound (to detect abnormalities that cause reflux)

• Renal ultrasound and renal scan (to evaluate hydronephrosis, kidney growth, and scarring)

• Urodynamic studies (e.g., filling cystometrogram, voiding cystometrogram)


Medication: Treatment for grades I – III VUR includes daily low-dose antibiotics (e.g., trimethoprim-sulphamethoxazole, amoxicillin) until the reflux resolves or until the child is at least 5 years old. These cases require regular monitoring by a pediatric urologist to diagnose UTI and prevent the condition from worsening.

Surgery: Secondary reflux that does not resolve with antibiotic treatment, or that results in UTI despite antibiotic therapy (called breakthrough infections), and primary reflux that is severe (grades IV and V) require surgery to prevent permanent kidney damage.

VUR can be treated in our our Robotic Surgery Program.

Newborn circumcision: Newborn males with VUR are recommended to undergo newborn circumcision to help prevent UTI. This is performed in our clinic.