• Clinical science

Vesicoureteral reflux (Vesicoureteral backflow…)

Abstract

Vesicoureteral reflux (VUR) is the retrograde flow of urine from the bladder into the ureter. Primary VUR is the most common type and is due to a congenital defect of the terminal portion of the ureter. Bladder outlet obstruction, cystitis, and congenital ureteral anomalies (e.g., ureteral duplication, ectopic ureter) may cause secondary VUR. Children with VUR are usually asymptomatic until they develop a urinary tract infection (fever, dysuria, urgency.). Other symptoms include flank pain and hypertension, uremia, and kidney failure in advanced cases of reflux nephropathy. The initial workup for VUR includes laboratory tests (creatinine levels, electrolytes) and renal ultrasound for evaluation of kidney function and possible structural damage. Voiding cystourethrogram is the diagnostic test of choice for demonstrating urinary reflux and the severity of the disease. Most cases of primary VUR resolve spontaneously as the child ages. Medical management with prophylactic antibiotics (e.g., trimethoprim-sulfamethoxazole, nitrofurantoin) and behavioral modification (timed micturition) is therefore successful in most cases. Patients with higher grades of primary VUR with ureteral dilation and hydronephrosis or with recurrent UTIs require endoscopic/surgical correction of the vesicoureteral junction. Treatment of the underlying cause corrects secondary VUR. Complications of VUR include hydronephrosis, obstructive nephropathy, pyelonephritis, and end-stage renal disease.

Epidemiology

References:[1]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

References:[1][2][3][4][5]

Clinical features

VUR is generally asymptomatic until it causes a urinary tract infection!

References:[1][2][6]

Diagnostics

Laboratory studies

Imaging

  • Ultrasound
  • Contrast voiding cystourethrogram (micturating cystourethrogram)
    • Indications
      • Children with ≥ 2 episodes of febrile UTIs or
      • First febrile UTI in a child and any of the following
    • Procedure: Contrast is instilled into the bladder through a Foley's catheter; images are obtained via fluoroscopy while the child is voiding.
    • Findings: Retrograde reflux of the contrast into the ureters during micturition is diagnostic of VUR.
    • Grading: VUR is divided into 5 grades of severity based on the results of the voiding cystourethrogram.
Grades of VUR Findings on voiding cystourethrogram

Grade I

  • Reflux limited to the ureter
  • No ureteral dilation

Grade II

Grade III

Grade IV

Grade V
  • Gross dilatation of the ureter, pelvis, and calyces
  • Significant ureteral tortuosity
  • Loss of papillary impressions
  • DMSA renal scan
    • Assessment of cortical tissue, renal function, and scarring (indicated in the case of hypodense photopenic lesions)
    • Further indicated for follow-ups and treatment monitoring
  • MAG3 scan (radionuclear cystourethrography) (MAG3: mercaptoacetyltriglycine; Tc99m-DTPA (diethylenetriaminepentacetate)
    • Detects VUR, especially if caused by obstructions , measures renal function
    • Follow-ups
  • Urodynamic testing: indicated in the evaluation of secondary VUR

References:[1][2][7][8][9][10]

Treatment

Conservative treatment

Surgical treatment

  • Indications
  • Subureteric transurethral injection (STING procedure)
    • Cystoscopy-guided injection of dextranomer/hyaluronic acid below the mucosa of the ureterovesical junction → fixes the intravesical ureter and alters the angle of the intramural ureter → correction of the VUR
    • Day-care procedure
    • Success rates of up to 90%
  • Surgery: ureteral reimplantation (ureteroneocystostomy)

References:[2][11][12][13][14][15]

Complications

References:[16]

We list the most important complications. The selection is not exhaustive.