Vesicoureteral reflux (VUR) is the retrograde flow of urine from the bladder into the upper urinary tract.
- The most common urinary finding in children:
- Occurs in 1%–2% of children < 2 years of age
- Prevalence is 15% in children with prenatal hydronephrosis
- 3 times more common in white children than Black children
- 2 times more common in girls than boys
- Genetic predisposition
- Congenital defect of the terminal portion of the ureter (e.g., short intravesical ureter)
- Anatomic causes:
- Posterior urethral valves
- Congenital ureteral duplication
- Bladder outlet obstruction
- Functional bladder obstruction:
- Neurogenic bladder (e.g., spina bifida)
- Detrusor instability
- The distal ureters course through the bladder wall at an oblique angle.
- During micturition, the bladder and the surrounding muscles contract and compress the intravesical ureter → prevention of urine reflux into the ureters
- A short intravesical ureter → ureter enters at a different angle
- Malfunction of the valve-like mechanism during micturition → reflux of urine into the ureter and collecting system
- Persistent intrarenal reflux → renal scarring → reflux nephropathy
- VUR → ↑ risk of urinary tract infections (UTIs), including pyelonephritis
Clinical Presentation and Diagnosis
There are no specific signs or symptoms for VUR, and the condition may be suspected in the following circumstances:
- Prenatal period: hydronephrosis noted on prenatal ultrasound (US)
- Postnatal period:
- UTI (often recurrent)
- Bowel or bladder dysfunction
Supporting laboratory evaluation
There are no laboratory tests that can diagnose VUR. The following assessments may be performed to evaluate for complications:
- BUN and creatinine → renal dysfunction
- Urinalysis with culture → UTI
Renal and bladder US:
- After 1st febrile UTI in all children aged 2–24 months
- In all children with recurrent cases of UTIs
- Potential findings:
- Dilated ureters
- Test of choice for the diagnosis and degree of VUR
- Bilateral hydronephrosis or renal scarring found on US
- 1st UTI with abnormal US
- Recurrent UTIs
- Contrast is placed in the bladder through a catheter.
- Fluoroscopy images are taken during voiding.
- Reflux of contrast into the ureter during voiding → VUR
Severity classification helps grade the severity of VUR based on imaging findings.
- Grade I: reflux into the ureter
- Grade II: reflux into the entirety of the ureter
- Grade III: Reflux fills and mildly dilates the ureter with mild blunting of the calyces.
- Grade IV: Reflux results in grossly dilated ureters and calyces. Some tortuosity of the ureter is also seen.
- Grade V: massive reflux causing significant dilation of the urinary collecting system and intrarenal reflux (“megaureter”)
Management and Prognosis
- Most cases resolve spontaneously.
- Appropriate for grades I and II
- Prompt treatment of UTIs
- Antibiotic prophylaxis:
- The goal is to prevent recurrent UTIs.
- Goal is to improve the angle of the ureter → ↓ reflux
- Grades IV or V
- Recurrent UTIs despite antibiotic prophylaxis
- Declining renal function
- Subureteric transurethral injection
- Open surgical reimplantation of ureters
- Most patients show spontaneous resolution of VUR.
- Factors that increase the likelihood of resolution:
- Lower severity of reflux
- Age of diagnosis < 2 years
- Unilateral disease
- Ureteropelvic junction obstruction: the most common cause of pediatric hydronephrosis. An anatomic lesion or functional disturbance causes an obstruction where the ureter enters the kidney. Ureteropelvic junction obstruction usually presents as a palpable abdominal mass, flank pain, hematuria, UTI, or failure to thrive. The diagnosis is made with imaging. A voiding cystourethrogram should be performed to rule out VUR. Management may include surveillance or surgery.
- UTI: a wide spectrum of diseases, ranging from self-limiting simple cystitis to severe pyelonephritis that can result in sepsis and death. Depending on the location of the infection, patients can present with dysuria, urinary urgency, increased urinary frequency, suprapubic pain, and fever. Urinalysis and urine culture along with the clinical presentation help in the diagnosis of UTIs. Imaging should be ordered to rule out VUR in children. Management options include oral or IV antibiotics.
- Posterior urethral valves: obstructing membranous folds within the lumen of the posterior urethra. Infants usually present with UTI, diminished urinary stream, urinary incontinence, and VUR. The diagnosis of posterior urethral valves can be made using US or a voiding cystourethrogram. Management is with surgery.
- Congenital megacalyces: an incidental finding resulting from the underdevelopment of the renal medullary pyramids. The resulting enlargement of the calyces can mimic hydronephrosis. The radiographic appearance of the calyces along with the normal caliber of the renal pelvis and ureter aid in the diagnosis. No management is required.
- Baskin, L.S. (2020). Congenital ureteropelvic junction obstruction. UpToDate. Retrieved March 12, 2021, from https://www.uptodate.com/contents/congenital-ureteropelvic-junction-obstruction
- Holmes, N. (2020). Clinical presentation and diagnosis of posterior urethral valves. UpToDate. Retrieved March 12, 2021, from https://www.uptodate.com/contents/clinical-presentation-and-diagnosis-of-posterior-urethral-valves
- Mattoo, T.K., Greenfield, S.P. (2021). Clinical presentation, diagnosis, and course of primary vesicoureteral reflux. UpToDate. Retrieved April 19, 2021, from https://www.uptodate.com/contents/clinical-presentation-diagnosis-and-course-of-primary-vesicoureteral-reflux
- Mattoo, T.K., Greenfield, S.P. (2021). Management of vesicoureteral reflux. In Kim, M.S. (Ed.), UpToDate. Retrieved April 25, 2021, from https://www.uptodate.com/contents/management-of-vesicoureteral-reflux
- Van Why, S.K., Avner, E.D. (2016). Vesicoureteral Reflux. Nelson Textbook of Pediatrics, 2562–67.
- Estrada, Jr., C.R., Cendron, M. (2018). Vesicoureteral reflux. In Kim, E.D. (Ed.), Medscape. Retrieved April 25, 2021, from https://emedicine.medscape.com/article/439403-overview
- Banker, H., Aeddula, N.R. (2020). Vesicoureteral reflux. [online] StatPearls. Retrieved April 25, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK563262/