Vesicoureteric Reflux

Vesicoureteric reflux is a condition where urine flows backward from the bladder toward the kidneys, most commonly affecting infants and young children. While many children outgrow this condition without lasting harm, understanding its causes, symptoms, and treatment options helps parents and caregivers protect their child’s kidney health.

Table of contents

• What Is Vesicoureteric Reflux?
• Types and Grades of VUR
• Who Is Affected by VUR?
• What Causes VUR?
• Signs and Symptoms
• How Doctors Diagnose VUR
• Treatment Options
• Outlook and Long-Term Health

What Is Vesicoureteric Reflux?

• Kidneys
• Ureters
• Bladder
• Urethra

Vesicoureteric reflux, also called vesicoureteral reflux or VUR, is a condition where urine flows in the wrong direction within the urinary system. Normally, your urinary tract works like a one-way street. The kidneys produce urine, which travels down through tubes called ureters (thin, muscular tubes) to the bladder (the storage organ for urine). When you urinate, the urine leaves your body through the urethra (the opening where urine comes out)^[1].

In children with VUR, urine flows backward—or refluxes—from the bladder back up into one or both ureters and sometimes reaches the kidneys. This happens because the valve-like mechanism that normally prevents backward flow doesn’t work properly^[1][2].

The condition is most common in infants and young children, particularly those age 2 and under. However, older children and even adults can have VUR, though this is less common^[3]. Most children don’t have long-term problems from VUR, and many outgrow the condition as they get older^[3].

The main concern with VUR is that when urine flows backward, bacteria can more easily reach the kidneys. This increases the risk of urinary tract infections (UTIs), which are infections in the urinary system. If left untreated, kidney infections can cause permanent kidney damage^[1][3].

Types and Grades of VUR

There are two main types of vesicoureteric reflux, depending on the underlying cause^[1]:

Primary VUR is the most common type. Children with primary VUR are born with a ureter that doesn’t connect properly into the bladder. The ureter doesn’t grow long enough during development before birth, which affects where it enters the bladder. This causes the flap valve between the ureter and bladder wall to not close correctly, allowing urine to flow backward. Primary VUR more commonly affects only one ureter and one kidney, which is called unilateral reflux^[1].

Secondary VUR happens when a blockage in the urinary tract causes increased pressure that pushes urine backward. The blockage might be an abnormal fold of tissue in the urethra that prevents urine from flowing freely out of the bladder. Another cause could be problems with nerves that can’t properly signal the bladder to release urine. Children with secondary VUR often have bilateral reflux, meaning it affects both ureters or both kidneys^[1].

Doctors grade VUR from 1 to 5 based on how far the urine backs up and whether the ureter is enlarged. Grade 1 is the mildest form, and grade 5 is the most severe^[1][3]:

• Grade 1: Urine goes backward up into a ureter, but the ureter remains a normal width^[1].
• Grade 2: Urine backs up into the ureter and reaches the kidney pelvis (the area where the ureter and kidney meet), but neither the kidney pelvis nor the ureter are enlarged^[1].
• Grade 3: Urine refluxes into the ureter and kidney, causing mild to moderate enlargement or swelling^[5].
• Grade 4: The ureter, kidney pelvis, and calyces (small cup-shaped structures in the kidney) are enlarged^[5].
• Grade 5: There is severe enlargement of the ureters, kidney pelvis, and calyces, with twisting of the ureter^[6].

Who Is Affected by VUR?

Vesicoureteric reflux is most often found in infants and young children. About 1 in 3 children who have a urinary tract infection with a fever has VUR. The actual number may be higher because some children with VUR don’t have symptoms and are never tested^[3].

The condition is more common in infants and children ages 2 and under. Generally, the younger a child is, the more likely they will have VUR^[3]. During infancy, VUR is more frequently seen in boys, but in older children, it is more often diagnosed in girls^[3][6].

VUR often runs in families. A child is more likely to have VUR if a brother, sister, or parent has the condition. A little more than 1 in 4 siblings of children with VUR will also have it. A little more than 1 in 3 children with a parent who had VUR will also develop the condition^[3]. Primary VUR is often a genetic condition passed down in families^[8].

Children who have abnormal kidneys or urinary tracts are more likely to have VUR^[3]. VUR can also occur in children with other urinary tract abnormalities such as posterior urethral valves, ureterocele, ureteral duplication, or bladder problems related to nerve or spinal cord conditions like spina bifida^[6].

What Causes VUR?

To understand what causes vesicoureteric reflux, it helps to know how the urinary system normally prevents backward flow of urine. When the ureters enter the bladder, they travel through the bladder wall at an angle, creating a tunnel. This tunnel acts like a valve. As the bladder fills with urine, pressure from the filling bladder pushes against the ureter and closes this tunnel, preventing urine from flowing back up^[4].

In primary VUR, the ureter didn’t grow long enough before birth. This means the ureter enters the bladder at an unusual angle or the tunnel through the bladder wall is too short. The valve mechanism doesn’t work properly, allowing urine to reflux backward^[8][15].

In secondary VUR, the backward flow happens because something blocks the normal flow of urine or increases pressure in the urinary system. Blockages can include abnormal tissue folds in the urethra, problems with bladder muscles, or nerve damage that prevents the bladder from emptying properly^[1]. Severe abnormal urinating patterns, such as excessive holding of urine, or being born with neural tube defects can also cause VUR^[14].

Signs and Symptoms

Many children with vesicoureteric reflux have no symptoms at all. Often, doctors discover the condition because a child develops a urinary tract infection with a fever^[8][3].

Sometimes VUR is found before a baby is born during a routine prenatal ultrasound. The test might show that the baby has swelling of the kidneys or ureter, a condition called hydronephrosis or urinary tract dilation^[8][12].

When children do have symptoms, the most common is a urinary tract infection. When urine flows backward, as it does with VUR, bacteria can grow more easily in the child’s urinary tract^[3].

A urinary tract infection lower in the urinary system, such as in the bladder, can cause^[8]:

• Frequent or urgent need to urinate
• Bedwetting and daytime accidents
• A burning feeling while urinating
• Blood in the urine, or urine that looks cloudy or smells bad

A urinary tract infection higher in the system, such as in the ureters or kidneys, can cause the same symptoms, plus^[8]:

• Pain in the side, back, or belly
• Fever and chills

Problems with bladder or bowel function can sometimes be related to VUR. Children with VUR may also have other bladder problems, such as urinary incontinence (loss of bladder control) or bedwetting^[3]. Some children may have trouble with urination, including urgency, dribbling, or wetting their pants, or may develop an abdominal mass from a swollen kidney^[14].

How Doctors Diagnose VUR

If your child has symptoms of a urinary tract infection, see a doctor right away. The doctor will do a physical exam, ask about your family medical history, and may order tests^[8].

A urine test can reveal whether your child has a UTI^[9]. Blood tests and urine tests can also check how well the kidneys are working and look for signs of infection or kidney damage^[8].

Several imaging tests help doctors diagnose VUR and determine its severity:

A kidney and bladder ultrasound uses sound waves to create images of the urinary tract. This test can find abnormalities in the kidneys, ureters, or bladder. It doesn’t require radiation and is painless. Ultrasound may be performed during pregnancy or after birth if swelling of the kidneys is suspected^[8][9].

A voiding cystourethrogram (VCUG) is the main test used to confirm VUR. During this test, a doctor places a thin, flexible tube called a catheter through the urethra into the bladder. A special dye called contrast material is injected into the bladder through the catheter. X-rays are taken while the bladder fills and when your child urinates. If your child has VUR, the contrast material will flow backward into the ureter and possibly the kidneys. The test takes about 15 to 20 minutes^[5][9].

The test may cause some discomfort from the catheter or from having a full bladder. Healthcare providers may give calming medicine called a sedative to help your child feel more comfortable. The test carries a small risk of causing a new urinary tract infection and exposes your child to a small amount of radiation^[9].

A nuclear scan, also called a radionuclide scan, uses a tracer substance to show whether the urinary system is working correctly. This test can detect urine reflux and check kidney function^[9].

A kidney scan (renal scan) may be performed if other tests are abnormal or if your child has repeated infections with fever. This test shows how well the kidneys function and drain, and can reveal kidney damage or scarring from previous infections^[12].

Treatment Options

Treatment for vesicoureteric reflux depends on several factors, including the severity of the condition (the grade), your child’s age, whether there are symptoms, and the risk of kidney damage. The main goals of treatment are to prevent urinary tract infections and protect the kidneys from damage^[13].

Many cases of VUR, especially lower grades in young children, resolve on their own as the child grows and the ureters lengthen. The chance of spontaneous resolution is high in children younger than 5 years with grades 1 to 3 reflux, and in children younger than 1 year, especially boys. Even higher grades of reflux (grades 4 and 5) may resolve spontaneously as long as the child remains free of infection^[13].

Active surveillance is an approach used for mild cases. The child is carefully monitored without immediate treatment. This approach is based on the knowledge that low-grade reflux often resolves on its own and that sterile reflux (reflux without infection) doesn’t damage the kidney^[13].

Medical treatment involves giving the child long-term low-dose antibiotics to prevent urinary tract infections. The philosophy behind this approach is that preventing infections protects the kidneys while waiting for the reflux to resolve naturally. If your child has problems with bladder or bowel function, these issues also need to be addressed as part of treatment^[13][17].

Surgical treatment may be recommended in certain situations. Surgery is considered when:

• The child has grades 4 or 5 reflux
• Reflux persists despite medical therapy, especially beyond 3 years
• The child has breakthrough urinary tract infections while taking preventive antibiotics
• There is progressive kidney scarring despite treatment
• The child has multiple drug allergies that prevent the use of preventive antibiotics
• The family or doctor wants to stop antibiotic treatment
• There is poor compliance with medical treatment^[13]

Two main types of surgery are available. Open surgical procedures involve an operation to reposition the ureter so it enters the bladder at the correct angle, creating a proper valve mechanism. Endoscopic injection is a less invasive option where a doctor injects a bulking material near the opening of the ureter into the bladder to help the valve close properly^[13].

During treatment, your child will need regular follow-up. This includes periodic urine tests to check for infections and imaging studies to monitor the kidneys and see if the reflux has improved^[17].

Outlook and Long-Term Health

Most children with vesicoureteric reflux have a good outlook. Many children outgrow VUR without lasting problems, especially those with lower grades of reflux diagnosed at a young age^[3][8].

The key to a good outcome is preventing urinary tract infections and kidney damage. When children remain free of infection, either through natural resolution, medical management, or surgery, their kidneys typically develop normally without scarring^[13].

If VUR is left untreated and urinary infections are not properly managed, complications can include permanent kidney damage or scarring, which in severe cases may lead to problems with kidney function, high blood pressure later in life, or concerns during pregnancy for females^[4].

Parents should watch for signs of urinary tract infections and seek prompt medical attention if symptoms develop. With proper monitoring and treatment, children with VUR can lead healthy, normal lives.