Vesicoureteral reflux (VUR)


Vesicoureteral reflux (VUR) is a medical condition characterized by the backward flow of urine from the bladder into the ureters and sometimes the kidneys. Normally, urine flows from the kidneys down the ureters and is stored in the bladder. 

Vesicoureteral reflux commonly occurs in newborns, infants, and children under the age of two, although it can also affect older children and, rarely, adults. This condition poses an increased risk of urinary tract infections, which, if left untreated, can lead to kidney damage. It is worth noting that VUR is more prevalent in girls than in boys. The grading system for VUR consists of five grades, ranging from one to five, with five being the most severe form. The grades are determined based on the extent of urine reflux into the urinary tract and the width of the ureter(s). 

  • Grade I: Urine flows backward into a normally sized ureter. 
  • Grade II: Urine refluxes into the kidney’s pelvis area through a normalsized ureter. The kidney pelvis and calyces, which collect and direct urine, remain unchanged in size. 
  • Grade III: The ureter(s), kidney pelvis, and calyces become mildly to moderately enlarged due to urine backup. 
  • Grade IV: The ureter(s) become moderately dilated and curved, and the kidney pelvis and calyces also display moderate dilation due to excessive urine accumulation. 
  • Grade V: The ureter(s) become extremely distorted and enlarged. The kidney pelvis and calyces exhibit significant enlargement caused by an excessive amount of retained urine. 

While some children may eventually outgrow primary vesicoureteral reflux, it is crucial to promptly address the condition to prevent kidney damage. Treatment options for VUR include medication and surgery, both aimed at safeguarding the health of the kidneys. 


Vesicoureteral reflux (VUR) often manifests without any noticeable symptoms in children. However, when symptoms do arise, the most common indicator is a urinary tract infection (UTI), which is frequently associated with VUR. It is estimated that around 30% to 50% of children diagnosed with UTI also have VUR. When VUR is present, it can create a conducive environment for bacterial growth in the urinary tract, leading to bladder and kidney infections. 

Some common signs and symptoms of VUR and its related complications include: 

  • Persistent and intense urge to urinate. 
  • Burning sensation during urination. 
  • Frequent need to pass small amounts of urine. 
  • Fever. 
  • Pain in the side (flank) or abdomen. 
  • Cloudy and foulsmelling urine. 

Diagnosing a urinary tract infection (UTI) in children can be challenging as they often exhibit nonspecific signs and symptoms. Infants with a UTI may also display the following indicators:   

  • Unexplained fever  
  • Decreased appetite  
  • Irritability 

As children progress in age without receiving treatment for vesicoureteral reflux, a condition characterized by the backward flow of urine from the bladder to the kidneys, several complications can arise. These include bedwetting, constipation or loss of bowel control, high blood pressure, and the presence of protein in the urine. Moreover, an additional indication of vesicoureteral reflux, detectable before birth through a sonogram, is the enlargement of the kidneys or the structures responsible for urine collection, known as hydronephrosis, which results from the accumulation of urine that flows back into the kidneys. 


The urinary system comprises the kidneys, ureters, bladder, and urethra, all working together to eliminate waste products through urine. The kidneys filter waste from the blood and produce urine, which is then carried by the ureters to the bladder for storage. When the bladder is full, urine is released from the body through the urethra during the process of urination. 

Vesicoureteral reflux can occur in two forms: primary and secondary. 


  • Primary vesicoureteral reflux: This type is more common and is present in children from birth. It is caused by a defect in the valve that normally prevents urine from flowing backward from the bladder into the ureters. Over time, as a child grows, the lengthening and straightening of the ureters may improve the valve function and correct the reflux. Primary vesicoureteral reflux often runs in families, suggesting a genetic component, although the exact cause of the defect is unknown. 
  • Secondary vesicoureteral reflux: The primary cause of secondary VUR is usually a blockage or narrowing in the bladder neck or urethra, leading to the backup of urine into the urinary tract instead of its proper exit through the urethra. Another contributing factor can be impaired nerve function in the bladder, which affects its ability to contract and relax normally, resulting in uncoordinated urine release. Secondary VUR is more commonly associated with bilateral reflux (affecting both sides) compared to unilateral reflux (affecting one side). In adults, vesicoureteral reflux is often associated with conditions such as benign prostate hypertrophy, neurogenic bladder, or previous surgeries near the ureters. 

Risk factors 

The follow factors increase the risk in developing vesicoureteral reflux:  

  • Family history: Primary vesicoureteral reflux often has a familial predisposition, with a family history of the disorder. Children are more likely to be affected if their parents already have the condition. Given the increased risk for siblings of affected children, healthcare providers may recommend screening for primary vesicoureteral reflux in siblings.  
  • Age: Older children are less likely to experience vesicoureteral reflux than infants and young children up to age 2.  
  • Sex. In general, females are more prone to experiencing this condition compared to males. However, there is an exception when it comes to vesicoureteral reflux present at birth, as it is more frequently observed in boys. 
  • Race: Vesicoureteral reflux appears to be more common in white children. 
  • Bladder and bowel dysfunction: Recurrent urinary tract infections and holding of urine and stools in children with bladder and bower dysfunction can cause vesicoureteral reflux.