What Is Vesicoureteral Reflux? A Plain-Language Guide to the Urine-Backflow Condition in Children
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
Vesicoureteral reflux is a condition in which urine flows backward from the bladder up the ureters toward the kidneys. [1] [4] It most often affects infants and children, and symptoms usually come from UTIs. [1] Untreated infections can scar the kidneys and cause high blood pressure or kidney failure. [1] Mild cases may be watched, while serious cases need antibiotics or surgery. [2]
What the research says
Daily low-dose antibiotics cut the risk of repeat UTIs by about half in children with reflux — but did not clearly reduce kidney scarring. In a randomized, placebo-controlled trial of 607 children with VUR, a repeat UTI developed in 39 of 302 children on prophylaxis versus 72 of 305 on placebo (hazard ratio 0.50, 95% CI 0.34 to 0.74). Kidney scarring did not differ significantly (11.9% vs 10.2%), and among children whose first recurrence was caused by E. coli, 63% of isolates in the prophylaxis group were resistant to trimethoprim-sulfamethoxazole versus 19% in the placebo group. (Hoberman et al., N Engl J Med, 2014) [5]
The newest meta-analysis agrees: fewer UTIs, but more antibiotic resistance and no change in new scarring. Pooling 13 randomized trials (2,577 children with VUR), continuous antibiotic prophylaxis lowered the risk of UTI (pooled odds ratio 0.79, 95% CI 0.65 to 0.94) but raised the risk of an antibiotic-resistant infection when a UTI did occur (pooled OR 6.96, 95% CI 4.35 to 11.02), with no difference in new kidney scarring (pooled OR 1.06, 95% CI 0.78 to 1.45). (Jhaveri et al., J Pediatr Urol, 2026) [6]
For grade II–IV reflux, the main treatment options probably perform similarly on UTI recurrence and kidney scarring. A network meta-analysis of 11 randomized trials (1,447 children) comparing antibiotic prophylaxis, surgery, endoscopic injection and conservative management found probably no difference between treatments in UTI recurrence, progression of existing scars, or new scar formation, and concluded that the choice should be individualized to each child's risk factors. (Chang et al., BMJ Paediatr Open, 2023) [7]
What Is Vesicoureteral Reflux?
Your urinary system has four main parts: the kidneys, ureters, bladder, and urethra. The kidneys sit toward the back of the upper belly. They filter waste and fluid from the blood and make urine. Urine moves from the kidneys to the bladder through narrow tubes called the ureters. The bladder stores urine until it's time to go, and urine leaves the body through a small tube called the urethra.
Vesicoureteral (ves-ih-koe-yoo-REE-tur-ul) reflux means that some urine flows in the wrong direction once it reaches the bladder. It flows back up the ureters instead of staying on its normal one-way path. [1]
Most often, VUR is found in infants and children. [1] Some children are born with it because of an issue with the structure of one of the two ureters. Others develop the condition later because the bladder isn't able to empty fully. [1]
With VUR, urine can carry germs from the bladder up to the kidneys. That raises the risk of urinary tract infections. Without treatment, those infections can lead to kidney damage. [1]
The good news: some children outgrow VUR on their own. Others need treatment such as medicine or surgery. [1] Either way, the goal is the same — prevent kidney damage and more UTIs.
What Are the Symptoms of Vesicoureteral Reflux?
VUR symptoms are often due to a UTI. A UTI doesn't always cause symptoms, but most people notice some. [1]
Symptom | What it looks like |
Strong urge to urinate | A strong, constant need to go |
Burning when urinating | A painful, burning feeling while peeing |
Frequent small urinations | The need to pass small amounts of urine often |
Cloudy urine | Urine that looks cloudy instead of clear |
Fever | An unexplained fever |
Pain | Pain in the side, groin, or stomach area [1] |
Babies and some small children can't tell adults what they're feeling. In these children, watch for:
A fever for no clear reason.
Lack of hunger.
Fussiness. [1]
What Happens If Vesicoureteral Reflux Goes Untreated?
Untreated vesicoureteral reflux can lead to a wider set of problems as a child gets older, and it can also cause swelling of the kidneys called hydronephrosis. [1]
Later problem | What it is |
Bed-wetting | Wetting the bed past the usual age |
Constipation or bowel control loss | Constipation or loss of control over bowel movements |
High blood pressure | Blood pressure that rises above the normal range |
Protein in urine | An early sign of kidney trouble found on a urine test |
Frequent or urgent urination | An urgent need to urinate or going more often than usual |
Urinary incontinence | Leaking urine by accident [1] |
Another sign of VUR is swelling of one or both kidneys, called hydronephrosis. It's caused by the backup of urine into the kidneys. An imaging test called an ultrasound often finds this swelling before a baby is even born. [1]
When Should I Call a Doctor?
Call a healthcare professional right away if your child has any UTI symptoms — a strong, persistent urge to urinate, a burning sensation when urinating, pain in the stomach area, groin, or side, or an upset stomach or vomiting. [1]
Also call about a fever if your child:
Child's age | Fever rule |
Younger than 3 months | A rectal temperature of 100.4°F (38°C) or higher. A child 2 months old or younger may need emergency care. [1] |
3 months or older | A fever of 100.4°F (38°C) or higher without other symptoms that lasts more than 24 hours. [1] |
Any age | Eating poorly, major mood changes, or looking or acting very sick. |
What Causes Vesicoureteral Reflux?
Vesicoureteral reflux has two main types with different causes: primary VUR from a faulty bladder valve present at birth, and secondary VUR usually from poor bladder emptying.
What Is Primary Vesicoureteral Reflux?
Children are born with this more common type. It's caused by a problem with the valve that usually keeps urine from flowing backward from the bladder. The valve doesn't close well. This lets urine flow back up the ureters instead of staying on its downward path. [1]
As children grow, the ureters lengthen and straighten. That may help the valve work better and correct the backflow over time. [1] This type tends to run in families, so it may be genetic — but the exact cause isn't known. [1]
What Is Secondary Vesicoureteral Reflux?
This type most often happens because the bladder doesn't empty properly. There can be many reasons for this: a fold of tissue may block urine from fully leaving the bladder, the muscles that connect the bladder to the urethra may become too narrow, or the nerves that control the bladder's ability to empty may become damaged. [1]
What Raises a Child's Risk of Vesicoureteral Reflux?
A child's risk of vesicoureteral reflux is higher with bladder and bowel dysfunction, and girls generally have a much higher risk than boys. [1] [3]
Risk factor | What it means |
Bladder and bowel dysfunction (BBD) | Children with BBD hold their urine and stool and get repeated UTIs, which can contribute to VUR |
Race | White children appear to have a higher risk than Black children |
Sex assigned at birth | Girls generally have a much higher risk than boys — except for reflux present at birth, which is more common in boys [1] |
Age | Infants and children up to age 2 are more likely to have VUR than older children |
Family history | Primary VUR tends to run in families; children whose parents had it — and siblings of a child with it — are at higher risk. Doctors may recommend screening tests for siblings. [1] |
What Are the Complications of Vesicoureteral Reflux?
The main health concern with VUR is kidney damage, and the worse the reflux, the more serious the complications are likely to be. [1]
Complication | What happens |
Kidney scarring | Without treatment, UTIs can lead to lasting damage to kidney tissue. Extensive scarring may lead to high blood pressure and kidney failure. [1] |
High blood pressure | Kidneys filter waste from the bloodstream. Damage lets waste build up, which in turn raises blood pressure. |
Kidney problems | Scarring can make an affected kidney struggle to filter blood. This may lead to kidney failure — either quickly (acute kidney injury) or over time (chronic kidney disease). [1] |
How Is Vesicoureteral Reflux Diagnosed?
A urine test can reveal whether your child has a UTI. [2] Other tests may then be needed to look at the urinary system itself.
Test | What it does |
Urine test | Reveals whether your child has a UTI |
Kidney and bladder ultrasound | Uses high-frequency sound waves to make images of the kidney and bladder; finds irregular organ parts. This same test is used during pregnancy to track a baby's development and may reveal swollen kidneys before birth. |
VCUG (voiding cystourethrogram) | A specialized X-ray of the urinary system. A thin, flexible tube (catheter) is placed through the urethra into the bladder, contrast dye is injected, and the full bladder is X-rayed. The catheter is then removed so the child can urinate, and more X-rays are taken while the bladder empties. It likely won't be painful, and a calming medicine (sedative) may be given first. Risks include catheter or full-bladder discomfort, a small chance of a new UTI, and a small amount of radiation. [2] |
Nuclear scan | Uses a tracer called a radioisotope to show whether the urinary tract is working correctly. It involves less radiation than a VCUG. [2] |
A practical tip: try to get tested at a center with lots of experience using catheters. If your child needs a VCUG, choose a center that knows how to minimize radiation exposure. [2]
What Do the Grades Mean?
After testing, doctors grade how severe the reflux is. With the mildest reflux (grade 1), urine backs up only to the ureter. The most serious reflux (grade 5) involves kidney swelling (hydronephrosis) and twisting of the ureter. [2]
Grade | What it means |
Grade 1 (mildest) | Urine backs up only to the ureter |
Grade 5 (most serious) | Kidney swelling (hydronephrosis) and twisting of the ureter |
How Is Vesicoureteral Reflux Treated?
Treatment depends on how serious the condition is. Children with mild primary VUR may outgrow it, so doctors may recommend a wait-and-see approach. More-serious VUR is treated with medications or surgery. [2]
How Are Medicines Used?
UTIs need to be treated quickly with antibiotics. These medicines keep the germs that cause the infection from moving up to the kidneys. To prevent UTIs from happening again, doctors may also prescribe antibiotics at a lower dose. [2]
A child on medicine needs to be watched until treatment is finished. That includes regular physical exams and urine tests to catch UTIs that happen anyway — called breakthrough infections. [2] Your child may also get occasional scans of the bladder and kidneys to check whether they've outgrown the VUR. [2]
When Is Surgery Needed?
Surgery may be needed if VUR doesn't improve with medicine — for instance, if your child keeps getting UTIs with fever. [2] Surgery can fix the leaky valve between the bladder and each affected ureter. [2] It's done under general anesthesia, which puts the child in a sleeplike state and prevents pain.
Surgery type | How it works | Pros | Cons |
Open surgery | The most common repair. The surgeon repairs the valve through an incision in the lower stomach area. | Most common and effective | Hospital recovery for a few days with a catheter in place; reflux may continue in a small number of children (though it often improves) [2] |
Robot-assisted laparoscopic surgery | The valve is repaired through small incisions using robotic arms with a camera and tools, controlled by a computer. | May irritate the bladder less; smaller, less visible scars | May not be as successful as open surgery; linked with more complications such as urine leakage [2] |
Endoscopic surgery | A lighted tube (cystoscope) is passed through the urethra, and a special gel is injected around the ureter opening. The gel forms a bulge that helps the valve close. | No skin incisions (minimally invasive); fewer risks than open surgery; usually same-day outpatient [2] | May not be as effective as open surgery [2] |
Rarely, some children with serious VUR need surgery to remove part or all of an affected kidney (nephrectomy) — for instance, if a kidney is badly infected and working poorly. [2]
What Home Steps Help Ease UTI Discomfort?
Simple home steps can ease a child's UTI discomfort from vesicoureteral reflux until antibiotics clear the infection, along with healthy toileting habits if needed.
What If Bladder and Bowel Dysfunction Plays a Part?
If BBD is involved, healthy toileting habits matter:
How Should I Prepare for My Child's Appointment?
VUR is usually spotted as part of follow-up testing when an infant or young child has a UTI. Call the doctor if your child has a long-lasting fever or pain or burning during urination. Your child may be referred to a urologist (a doctor who finds and treats urinary tract conditions) or a nephrologist (a doctor who finds and treats kidney conditions). [2]
Before the appointment, write down: your child's symptoms and how long they've lasted; their medical history including other recent health problems; the family's medical history (especially whether first-degree relatives like parents or siblings have had VUR); all medicines, vitamins, and supplements with doses; and the questions you want to ask.
Questions to ask | Questions the doctor will ask you |
What's the most likely cause of my child's symptoms? Could it be a bladder or kidney infection instead? | When did you first notice the symptoms? |
What kinds of tests does my child need? | Do the symptoms happen all the time or come and go? |
How likely is it the condition gets better without treatment — or what are the benefits and risks of treatment? | How bad are the symptoms, and what improves or worsens them? |
Is my child at risk of complications, and how will you watch them over time? | Does anyone in your family have a history of VUR? |
What steps can I take to lower the UTI risk? | Has your child had growth problems? |
Are my other children at increased risk? | What antibiotics has your child had for other infections, such as ear infections? |
Do you recommend my child see a specialist? | — |
The best treatment option often isn't clear-cut. Choosing what's right for your child depends on understanding the condition — and each treatment's benefits and risks.
What is the bottom line on vesicoureteral reflux?
Vesicoureteral reflux means a child's urine flows backward from the bladder toward the kidneys. It usually shows up through UTI symptoms — burning when urinating, fever, belly or side pain — in infants and young children. Some children outgrow mild VUR with simple watchful waiting, while more serious cases need antibiotics or surgery to repair the leaky valve. Because untreated UTIs can scar the kidneys and eventually raise blood pressure or cause kidney failure, prompt testing and regular follow-up matter. If your child has recurring UTIs or fevers without an obvious cause, ask the doctor whether VUR could be part of the picture.
Take the Next Step
If your child has a UTI — especially a second one — or an unexplained fever in infancy, ask the healthcare professional whether testing for vesicoureteral reflux is warranted. Early diagnosis, regular follow-up, and simple home habits (fluids, regular bathroom breaks, constipation prevention) protect young kidneys while you and your doctor decide the right path forward.
Frequently Asked Questions
What is vesicoureteral reflux?
A condition in which some urine flows the wrong direction once it reaches the bladder, backing up the ureters toward the kidneys instead of traveling only one way down. [1]
Who gets vesicoureteral reflux?
Most often infants and children. Some are born with it (a valve problem), while others develop it later when the bladder can't empty fully. [1]
What are the symptoms?
Symptoms usually come from UTIs — a strong urge to urinate, burning when urinating, frequent small urinations, cloudy urine, fever, and pain in the side, groin, or stomach area. [1]
Is vesicoureteral reflux dangerous?
Untreated UTIs caused by the backflow can lead to kidney scarring, high blood pressure, and even kidney failure. [1] That's why diagnosis and follow-up matter.
How serious is my child's reflux?
Doctors grade reflux from 1 (mildest — urine backs up only to the ureter) to 5 (most serious — kidney swelling and twisting of the ureter). [2]
Will my child outgrow it?
Some children with mild primary VUR do outgrow it as the ureters lengthen and straighten. [1] Doctors may recommend a wait-and-see approach for mild cases. [2]
How is it treated?
Antibiotics to treat and prevent UTIs, regular checkups and occasional scans, or surgery to repair the leaky valve — open, robot-assisted laparoscopic, or endoscopic. [2]
Are my other children at risk?
Primary VUR tends to run in families. [1] Parents and siblings of an affected child have a higher risk, so doctors may recommend screening tests for siblings. [1]
How is vesicoureteral reflux diagnosed?
A urine test checks for infection, and a kidney and bladder ultrasound looks at the urinary organs. A special X-ray called a voiding cystourethrogram (VCUG) shows whether urine flows backward and how severe it is.
Does my child need to take antibiotics every day?
Some children with reflux take a low daily dose of antibiotics to help prevent new urinary tract infections. Your child's provider will decide based on the grade of reflux and how often infections happen.
Related Reading
Fluoroscopy: What It Is, How It Works, Risks and What to Expect explains the real-time X-ray imaging used in many exams and procedures for this condition.
Renal Scan (Kidney Scan): Types, Preparation, Risks and Results explains the nuclear medicine scan used to measure kidney function, blood flow and blockages.
Voiding Cystourethrogram (VCUG): Why It's Done, What to Expect and Reflux Grades explains the X-ray test used to diagnose urine reflux in children.
References
Mayo Clinic Staff. Vesicoureteral reflux: Symptoms and causes. Mayo Clinic. Last updated February 5, 2025. Accessed October 15, 2026. https://www.mayoclinic.org/diseases-conditions/vesicoureteral-reflux/symptoms-causes/syc-20378819
Mayo Clinic Staff. Vesicoureteral reflux: Diagnosis and treatment. Mayo Clinic. Last updated February 5, 2025. Accessed October 15, 2026. https://www.mayoclinic.org/diseases-conditions/vesicoureteral-reflux/diagnosis-treatment/drc-20378824
National Institute of Diabetes and Digestive and Kidney Diseases. Vesicoureteral reflux (VUR). NIDDK. Last reviewed June 2018. Accessed October 15, 2026. https://www.niddk.nih.gov/health-information/urologic-diseases/hydronephrosis-newborns/vesicoureteral-reflux
National Kidney Foundation. Vesicoureteral reflux (VUR) in infants & children. National Kidney Foundation. Accessed October 15, 2026. https://www.kidney.org/kidney-topics/vesicoureteral-reflux-vur-infants-children
Hoberman A, Greenfield SP, Mattoo TK, et al. Antimicrobial prophylaxis for children with vesicoureteral reflux. N Engl J Med. 2014;370(25):2367-2376. PMID 24795142. https://doi.org/10.1056/NEJMoa1401811
Jhaveri H, Stewart A, Aitelli A, et al. Efficacy of antibiotic prophylaxis in children with vesicoureteral reflux: Systematic review and meta-analysis of randomized clinical trials. J Pediatr Urol. 2026;22(3):105829. PMID 41785522. https://doi.org/10.1016/j.jpurol.2026.105829
Chang CL, Yang SS, Hsu CK, et al. Effectiveness of various treatment modalities in children with vesicoureteral reflux grades II-IV: a systematic review and network meta-analysis. BMJ Paediatr Open. 2023;7(1):e002096. PMID 37989356. https://doi.org/10.1136/bmjpo-2023-002096
Medical disclaimer
This content is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions about your child's medical condition.
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