Vesicoureteral reflux is retrograde passage of urine from the bladder back into the ureter and sometimes also into the renal collecting system, depending on severity. Reflux predisposes to urinary tract infection, often recurrent. Evaluation includes ultrasonography of the kidneys, ureters, and bladder before and after voiding, and then fluoroscopic voiding cystourethrography (VCUG). Treatment depends on the cause and severity.
Vesicoureteral reflux (VUR) is the most common urologic anomaly in children, with an estimated prevalence of approximately 1 to 2% in the general pediatric population (1). Because VUR has a strong familial component, siblings of an affected child have a markedly higher risk of developing it than the general population. VUR prevalence rates of 26 to 50% in siblings have been reported. As a result, parents may opt to have asymptomatic siblings screened.
General reference
1. Puri P, Friedmacher F, Farrugia MK, Sharma S, Esposito C, Mattoo TK. Primary vesicoureteral reflux. Nat Rev Dis Primers. 2024;10(1):75. Published 2024 Oct 10. doi:10.1038/s41572-024-00560-8
Etiology of VUR
Vesicoureteral reflux (VUR) is most often due to congenital anomalous development of the ureterovesical junction. Incomplete development of the intramural ureteral tunnel causes failure of the normal flap valve mechanism at the ureterovesical junction, thus permitting reflux of bladder urine into the ureter and renal pelvis. Reflux can occur even when the tunnel is ordinarily sufficient if bladder pressure increases due to bladder outlet obstruction, neurogenic bladder, or dysfunctional voiding. Dysfunctional elimination syndrome includes infrequent voiding, constipation, or both, which may prolong resolution of VUR. Constipation can affect bladder emptying and increases bacterial load in the rectum and perineum. Bowel and bladder dysfunction increases the risk of urinary tract infections (UTIs).
Pathophysiology of VUR
Reflux of urine from the bladder into the ureter may damage the upper urinary tract by bacterial infection and occasionally by increased hydrostatic pressure. Bacteria in the lower urinary tract can easily be transmitted by reflux to the upper tract, leading to recurrent parenchymal infection with potential scarring. Renal scarring can eventually cause hypertension and sometimes renal dysfunction. VUR is a common cause of UTI in children; about 30 to 40% of infants and toddlers with UTI have VUR (1).
Pathophysiology reference
1. Chao TC, Lim LY, Yang SS. Mechanism of vesicoureteral reflux: High detrusor pressure versus low ureteral resistance: A narrative review. Pediatr Neonatol. 2025;66(5):414-418. doi:10.1016/j.pedneo.2025.01.013
Symptoms and Signs of VUR
VUR does not cause characteristic symptoms or physical findings on its own; it is usually detected during evaluation of a urinary tract infection (UTI), prenatally detected hydronephrosis, or an associated anomaly.
Neonates with UTI may have nonspecific symptoms and signs that include fever, poor feeding, lethargy, and vomiting. Infants and children < 2 years old with UTI may also present with poorly localizing signs such as fever or gastrointestinal symptoms (eg, vomiting or abdominal pain). Children > 2 years old with UTI may have symptoms and signs of cystitis, such as fever, abdominal or flank pain, dysuria, frequency, urgency, daytime and nocturnal enuresis, and rarely hematuria, or symptoms of pyelonephritis. (See also Symptoms and Signs of UTI in Children.)
Some children do not have symptoms.
When physical findings are present, they reflect a coexisting anomaly rather than the reflux itself. For example, an abdominal mass or palpable enlarged kidney may reflect associated hydronephrosis or renal dysplasia; an abnormal urethral orifice, signs of lower spinal malformation, or a diminished urinary stream suggests secondary reflux resulting from posterior urethral valves, obstruction, or neurogenic bladder.
Rarely, children present with hypertension, which is more commonly a long-term consequence of renal scarring.
Diagnosis of VUR
Ultrasonography
Voiding cystourethrography (VCUG)
Sometimes radioisotope scan
Urinalysis and culture are performed to detect infection. In infants and young children, a catheterized specimen is usually required.
Evaluation includes ultrasound of the kidneys, ureters, and bladder before and after voiding, and then fluoroscopic VCUG. Renal ultrasound is used to evaluate kidneys for size, hydronephrosis, and scarring. VCUG is used to diagnose VUR and to evaluate for other bladder anomalies. A radioisotope cystogram (radionuclide cystography) and contrast-enhanced voiding ultrasound are alternatives that may be used to diagnose or monitor reflux. Renal cortical involvement with acute infection or scarring is best diagnosed with technetium-99m–labeled dimercaptosuccinic acid (DMSA) nuclear scans when indicated. Urodynamic studies, when appropriate, may show elevated intravesical pressure (1) causing secondary reflux. These findings may be seen in patients with neurogenic bladder or severe voiding dysfunction.
Reflux findings on VCUG are graded on a scale from I to V (see table ). The degree of reflux can be affected by bladder capacity and bladder dynamics:
Mild: Grades I and II
Moderate: Grade III
Severe: Grades IV and V
Grades of Vesicoureteral Reflux*
Grade | Characteristics |
|---|---|
I | Only the ureters are involved; the renal pelvis is not. |
II | Reflux reaches the renal pelvis, but the calyces are not dilated. |
III | The ureter and renal pelvis are dilated, with minimal or no blunting of calyces. |
IV | Dilation increases, and the sharp angle of the calyceal fornices is obliterated. |
V | The ureter, pelvis, and calices are grossly dilated. Papillary impressions frequently are absent. |
* As defined by the International Reflux Study Committee. | |
Lebowitz RL, Olbing H, Parkkulainen KV, et al. International system of radiographic grading of vesicoureteric reflux. International Reflux Study in Children. Pediatr Radiol. 1985:15(2):105–109. doi:10.1007/BF02388714 | |
Diagnosis reference
1. American Urological Association. Management and Screening of Primary Vesicoureteral Reflux in Children (2017). 2017. Accessed July 31, 2026.
Treatment of VUR
Sometimes antibiotic prophylaxis
Sometimes injection of a bulking agent or ureteral reimplantation
Mild to moderate vesicoureteral reflux often resolves spontaneously over months to several years. It is very important to keep children free of infection. Previously, children with mild to moderate VUR were given daily antibacterial prophylaxis, but there is currently no consensus on this practice (1, 2).
Severe vesicoureteral reflux accompanied by high intravesical pressures is treated with anticholinergic medications (eg, oxybutynin, solifenacin succinate), a beta-3 agonist (eg, mirabegron), and/or rarely surgery (such as botulinum toxin injection or bladder augmentation). Most pediatric urologists recommend prophylactic antibiotics for severe VUR in children in all age groups, for VUR grades III to V in children < 1 year of age, and for children in all age groups with recurrent febrile UTIs independent of VUR grade or with significant bladder/bowel dysfunction (1, 2). There are multiple age- and weight-based recommendations for antibiotics, but, typically, children are given trimethoprim/sulfamethoxazole at bedtime, nitrofurantoin at dinnertime, or cephalexin 2 times/day. Patients with bowel/bladder dysfunction benefit from behavioral modification with or without biofeedback (1).
Symptomatic reflux that causes recurrent infections, impaired renal growth, renal scarring, or bladder dysfunction is treated with endoscopic injection of a bulking agent (eg, dextranomer/hyaluronic acid) to decrease the size of the ureteral orifice and compress the distal ureter or with ureteral reimplantation to increase the ureteral tunnel length.
Monitoring
History, physical examination (including blood pressure measurement), laboratory testing with urinalysis (to look for hematuria and proteinuria) and serum creatinine, and imaging using VCUG and ultrasound are performed at regular intervals depending on the child's age and on the severity of the reflux and associated complications.
Typically, ultrasound should be performed every 12 months.
VCUGs may be repeated every 1 to 2 years, but intervals for children with VUR grades III to V, with bilateral VUR, or who are older should be less frequent because the time to resolution may take longer (1).
Technetium-99m–labeled dimercaptosuccinic acid (DMSA) scans may be performed if anomalies (eg, scarring) are seen on ultrasound, to assess patients for new scarring after a febrile UTI, or in patients with an elevated creatinine or cystatin C level.
In addition, toilet-trained children should be assessed at each visit for constipation and infrequent voiding, incontinence, urinary urgency, and enuresis, which are common signs of elimination dysfunction, and treated as needed with behavioral modification and/or medication therapy.
Treatment references
1. American Urological Association. Management and Screening of Primary Vesicoureteral Reflux in Children (2017). 2017. Accessed July 31, 2026.
2. RIVUR Trial Investigators; Hoberman A, Greenfield SP, Mattoo TK, Keren R, Mathews R, Pohl HG, Kropp BP, Skoog SJ, Nelson CP, Moxey-Mims M, Chesney RW, Carpenter MA. Antimicrobial prophylaxis for children with vesicoureteral reflux. N Engl J Med. 2014 Jun 19;370(25):2367-76. doi:10.1056/NEJMoa1401811. Epub 2014 May 4. PMID: 24795142; PMCID: PMC4137319.
Key Points
Vesicoureteral reflux (VUR) is most often due to congenital anomalous development of the ureterovesical junction.
Reflux of urine from the bladder into the ureter may cause bacterial infection of the upper urinary tract; about 30 to 40% of infants and toddlers with urinary tract infection have VUR.
Diagnose by performing fluoroscopic voiding cystourethrography (VCUG).
Mild to moderate VUR often resolves spontaneously, but more serious disease may rarely require surgical intervention.
Anticholinergic medications or beta-3 agonists may be used for patients with high bladder pressures causing secondary reflux.
Give prophylactic antibiotics for severe VUR in children in all age groups, for VUR grades III to V in children < 1 year of age, and for children in all age groups with recurrent febrile UTIs independent of VUR grade or with significant bladder/bowel dysfunction.
Monitor by using serial ultrasounds and VCUGs.
Assess toilet-trained children for bowel/bladder dysfunction and treat them appropriately.
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