Vesicoureteral Reflux

Written & reviewed by the BestDoctors.sg editorial team · Last updated 2 Sep 2026 · General information, not medical advice

If your child has had a urinary tract infection or a scan has shown swelling of the kidney, the doctor may mention vesicoureteral reflux. It can sound worrying, but it is a common finding in young children and is often mild. This guide explains, in plain terms, what VUR is, how it is found, how it is treated, and when to seek help. It is general information and does not replace advice about your own child.

What it is

Normally urine is made in the kidneys, flows down the ureters to the bladder, and is stored there until your child passes it out. Where each ureter enters the bladder there is a valve-like arrangement that should only let urine go one way – downwards, into the bladder. In vesicoureteral reflux this one-way mechanism does not work properly, so some urine flows backwards up the ureter towards the kidney when the bladder fills or empties. This matters because urine that washes back up can carry bacteria from a bladder infection up to the kidneys, and because reflux that is severe or keeps causing infections can, over time, affect kidney growth and function.

How it is usually found

VUR is often picked up in one of two ways. The first is after a child has had a urinary tract infection, especially one with a fever or one that keeps coming back – doctors may then look for an underlying reason. The second is before birth or soon after, when an antenatal ultrasound shows swelling of a baby’s kidney (this is called hydronephrosis) and further checks are arranged after delivery. Some children have no symptoms at all and the reflux is only found because of these investigations.

Symptoms

Reflux by itself usually causes no symptoms. The clues instead come from the urine infections it can lead to. In older children, watch for pain or burning when passing urine, needing to go more often, cloudy or strong-smelling urine, tummy or side pain, fever, and new bedwetting or daytime wetting after previously being dry. In babies, signs can be vague – poor feeding, irritability, being unsettled, or an unexplained fever with no obvious cause. Because babies cannot tell you what is wrong, an unexplained fever always deserves a check.

Grades in plain terms

Doctors describe VUR as ranging from mild to severe. In milder reflux, only a small amount of urine flows back a short way and the kidney looks normal. In more severe reflux, larger amounts wash back and the ureter and kidney may look swollen or stretched. The grade matters because it helps guide treatment and gives a sense of the outlook: milder cases very often settle on their own as the child grows and the valve matures, while more severe or persistent cases are watched more closely and are more likely to need active treatment.

Causes and who is at risk

Most VUR is a developmental issue that is present from birth – the valve where the ureter meets the bladder simply has not formed or matured fully. It is not caused by anything a parent did or did not do. VUR can run in families, so a child with a parent or sibling who had reflux is more likely to have it. It is also linked with the way the bladder and bowel work: children who hold on to urine, do not empty the bladder fully, or who are constipated can put extra pressure on the system, which is why good bladder and bowel habits are part of care.

How it is diagnosed

Several simple tests are used together. A urine test checks for infection. An ultrasound of the kidneys and bladder gives a painless picture of their size and shape and shows any swelling. To see the reflux itself, a special X-ray test is done while the bladder fills and empties – a “voiding” study, in which a fine tube is used to fill the bladder with a dye that shows up on X-ray, so doctors can see whether urine flows backwards. Sometimes a kidney scan is added to check how well the kidneys are working and whether there is any scarring. Your child’s doctor will explain which tests are needed and why.

Treatment

Treatment depends on how severe the reflux is, your child’s age, and whether infections keep happening. Many milder cases are managed by watchful waiting, because reflux so often resolves on its own with growth. Alongside this, the focus is on preventing and promptly treating urine infections, and on building good bladder and bowel habits – regular, unhurried toilet visits, emptying the bladder fully, drinking enough water, and treating constipation. In some children, a low-dose preventive antibiotic is given to lower the chance of infection while the reflux settles. For severe or persistent reflux that keeps causing infections or is affecting the kidneys, doctors may recommend a procedure or surgery to correct the valve so urine no longer flows backwards. A paediatric urologist will discuss the options and what suits your child best.

Living with it and follow-up

For most families, living with VUR means regular monitoring rather than daily treatment. Follow-up may include repeat ultrasounds or scans to see whether the reflux is improving and to keep an eye on kidney growth. The everyday priorities are simple: treat urine infections promptly, keep up good toileting habits, encourage your child to drink enough and not to hold on for too long, and manage constipation. Tell any doctor treating your child for a fever that your child has reflux, so a urine infection is considered early.

When to seek urgent help

Seek urgent medical care if your child has a high fever together with back, side or tummy pain, seems very unwell, floppy or drowsy, is vomiting repeatedly, or is a baby with an unexplained fever. These can point to a kidney infection, which needs prompt treatment. If your child is very unwell, take them to the nearest A&E or call 995. When in doubt, it is always safer to have your child checked.

Common questions

Will my child grow out of vesicoureteral reflux?

Many children do. Milder reflux in particular often improves or resolves on its own as the child grows and the valve matures, which is why watchful waiting is common. Your doctor will monitor progress over time.

Does VUR damage the kidneys?

Reflux on its own does not usually harm the kidneys. The concern is repeated urine infections reaching the kidney, or severe reflux, which can affect kidney growth. Preventing and promptly treating infections is the main way to protect the kidneys.

Is the voiding X-ray test painful for my child?

It can be uncomfortable because a fine tube is passed into the bladder, but it is not usually described as very painful and is done gently by staff experienced with children. The team will explain what happens and help keep your child calm.

Can good toilet and bowel habits really help?

Yes. Emptying the bladder fully, not holding on for long periods, drinking enough water, and avoiding constipation all reduce pressure on the system and lower the chance of infection, which supports the reflux settling.

Does VUR run in families?

It can. Reflux is more common in children who have a parent or sibling who had it, so let your doctor know if there is a family history – siblings are sometimes checked.

Related guides

• Urinary tract infection
• Kidney infection
• Bedwetting
• Hydronephrosis

Sources

• KK Women’s and Children’s Hospital
• HealthHub
• National Kidney Foundation
• NHS