Key Facts

Vesicoureteral reflux is the most common urological anomaly in children. It predisposes to pyelonephritis through the retrograde transport of infected urine to the kidneys. Early detection and management aim to prevent renal scarring and long-term complications such as hypertension and chronic kidney disease.

Epidemiology

VUR has a prevalence of approximately 1-2% in the general paediatric population. It is identified in 30-40% of children investigated after a UTI. There is a strong familial tendency — 30-50% of siblings and 66% of offspring of affected parents also have VUR. It is more common in Caucasian children and shows a female predominance for clinical presentation (male predominance in antenatally detected cases).

Aetiology

Primary VUR: Congenital deficiency of the submucosal tunnel of the ureterovesical junction. The normal ratio of tunnel length to ureteric diameter is 5:1; this is reduced in VUR.

Secondary VUR: Due to elevated intravesical pressure — posterior urethral valves, neuropathic bladder, bladder outlet obstruction, dysfunctional voiding.

Pathophysiology

The ureterovesical junction normally acts as a one-way valve. During bladder filling and voiding, the intramural ureter is compressed against the detrusor muscle, preventing reflux. When this mechanism is deficient, urine refluxes retrogradely. If urine is infected, bacteria reach the renal parenchyma causing pyelonephritis. Repeated pyelonephritis leads to renal scarring (reflux nephropathy), characterised by cortical thinning and calyceal clubbing, particularly at the renal poles.

Antenatal Detection

• Antenatal hydronephrosis identified on routine ultrasound
• More common in male infants

UTI Presentation

• Fever, vomiting, poor feeding in infants
• Dysuria, frequency, abdominal/loin pain in older children
• Offensive/cloudy urine
• Failure to thrive in recurrent cases

Complications

• Recurrent febrile UTIs
• Renal scarring — may be asymptomatic initially
• Hypertension (detected on routine monitoring)
• Proteinuria (indicating renal damage)

Red Flags

• Recurrent febrile UTIs in any child — investigate for underlying urological abnormality
• Hypertension in a child with known VUR — suggests renal scarring
• Poor growth or chronic kidney disease features
• Bilateral high-grade reflux with impaired renal function

Bedside

• Urine dipstick and MC&S: Confirm UTI diagnosis
• Blood pressure: Screen for hypertension secondary to renal scarring
• Growth assessment: Plot height and weight on centile charts

Bloods

• U&Es, creatinine: Assess renal function
• FBC, CRP: During acute infection episodes
• Urine protein:creatinine ratio: Screen for proteinuria indicating renal damage

Imaging

• Renal ultrasound: First-line — assess kidney size, hydronephrosis, cortical thinning; does not reliably detect VUR
• MCUG (micturating cystourethrogram): Gold standard for diagnosing and grading VUR (grades I-V). NICE CG54 recommends in infants <6 months with atypical/recurrent UTI
• DMSA scan: Static renal scan to detect cortical scarring — perform 4-6 months after acute infection
• MAG3 renogram: Assess differential renal function and drainage

Special Tests

• Indirect radionuclide cystography: Lower radiation alternative to MCUG for follow-up
• Urodynamic studies: If secondary VUR suspected (neuropathic bladder, dysfunctional voiding)

Non-pharmacological

• Ensure adequate fluid intake and regular voiding
• Manage constipation (commonly coexists and worsens VUR)
• Treat bladder-bowel dysfunction with behavioural strategies
• Parental education on UTI recognition and prompt treatment

Pharmacological

• Antibiotic prophylaxis: Trimethoprim 1-2mg/kg nocte or nitrofurantoin 1mg/kg nocte — consider in recurrent UTI or high-grade VUR (RIVUR trial showed 50% reduction in recurrent UTI)
• Prompt treatment of UTIs: Cefalexin 12.5mg/kg BD for 7-10 days (oral) or IV ceftriaxone 80mg/kg OD for pyelonephritis
• Anticholinergics: Oxybutynin 0.2mg/kg BD-TDS if overactive bladder contributes

Surgical/Interventional

• Endoscopic subureteric injection (Deflux/dextranomer-hyaluronic acid): Day case procedure; 70-80% success rate for grade III-IV
• Ureteric reimplantation (Cohen or Politano-Leadbetter): >95% success rate; reserved for high-grade VUR, failed endoscopic treatment, or breakthrough infections on prophylaxis

Referral Criteria

• All children with confirmed VUR — paediatric urology/nephrology
• Recurrent febrile UTIs despite prophylaxis
• Evidence of new renal scarring on DMSA
• Hypertension or declining renal function

• Grades I-II: Spontaneous resolution in approximately 80% by age 5 years
• Grade III: Resolution in approximately 50% by age 5
• Grades IV-V: Spontaneous resolution uncommon (<20%); higher risk of renal scarring
• Renal scarring: Occurs in 10-40% of children with VUR; risk increases with delayed treatment of UTIs
• Reflux nephropathy: Accounts for 5-10% of children reaching end-stage renal disease
• Bilateral high-grade VUR: Greater risk of CKD — long-term renal function monitoring essential

VUR Grading (International Classification)

NICE CG54 Imaging Recommendations for UTI in Children