Vesicoureteral reflux (Vesicoureteral backflow…)

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.

• Primary VUR (most common type): short intramural ureter → vesicoureteric junction (VUJ) fails to close completely during bladder contraction → VUR
• Secondary VUR
  • Bladder outlet obstruction (anatomic/functional): high pressure within the bladder → reflux of urine through the VUJ
    • Anatomic: posterior urethral valves; ; urethral meatal stenosis
    • Functional: bladder and bowel dysfunction ; neurogenic bladder
    • Cystitis
  • Congenital anomalies of the ureter
    • Ureteral duplication (most common renal abnormality; 1% of the population)
    • Ectopic ureter
    • Ureterocele
  • Iatrogenic

References:^{[1][2][3][4][5]}

• Suspected in the prenatal period when hydronephrosis is detected on routine antenatal ultrasound
• Postnatal presentation
  • Recurrent febrile urinary tract infections
    • Neonates: irritability, fever, and listlessness
    • Older children: urinary urgency, frequency, incontinence, and dysuria associated with fever
  • Reflux nephropathy : renovascular hypertension, kidney failure, uremia
  • Flank or abdominal pain before or during voiding

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

References:^[1][2][6]

Laboratory studies

• Urinalysis and urine culture: indicated in all children with hydronephrosis to rule out infection
• Renal function tests: serum creatinine, urea, and electrolytes

Imaging

• Ultrasound
  • Indicated in children with febrile UTI and for follow-ups
  • Detection of hydronephrosis and dilated ureter
• 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:
      • A renal anomaly detected on ultrasound
      • Fever ≥ 39°C (102.2°F) and a pathogen other than E. coli detected in urine culture
      • Hypertension
  • Procedure: Contrast is instilled into the bladder through a urethral 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	Reflux up to the renal pelvis No ureteral dilation
Grade III	Reflux up to the renal pelvis Mild dilation of the ureter Blunting of the calyces
Grade IV	Reflux up to the renal pelvis Gross dilation of the ureter Moderate ureteral tortuosity
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]}

• Pyelonephritis and perinephric abscess
• Urosepsis
• Renal scarring
• End-stage renal disease

References:^[16]

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