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Vesicoureteral Reflux (VUR)

DISEASE DEFINITION

Vesicoureteral Reflux (VUR), also known as vesicoureteric reflux, is a condition in which urine flows retrograde, or backward, from the bladder into one or both ureters and then to the kidneys. Urine normally travels in one direction (forward, or anterograde) from the kidneys to the bladder via the ureters, with a one-way valve at the vesicoureteral (ureteral-bladder) junction preventing backflow. The valve is formed by oblique tunneling of the distal ureter through the wall of the bladder, creating a short length of ureter (1–2 cm) that can be compressed as the bladder fills. Reflux occurs if the ureter enters the bladder without sufficient tunneling, i.e. without a natural closure mechanism in the bladder wall. It can also occur secondarily especially in the case of impaired bladder function or obstruction. The severity of VUR is described by a grading system according to the findings of a voiding cystourethrogram (VCUG), with grades ranging from I (mild) to V (severe).

SYMPTOMS

In most adult cases, VUR does not directly cause any symptoms, but VUR increases risk of acute bladder and kidney infections. VUR can be diagnosed as a result of further investigation of a known enlargement of the kidney or ureters or after the occurrence of symptomatic urinary tract infections. 

In infants, the signs and symptoms of a urinary tract infection may include:

  • fever and lethargy
  • poor appetite
  • sometimes foul-smelling urine
  • discomfort or pain with urination
  • frequent urination or enuresis.

DIAGNOSIS

The following procedures may be used to diagnose VUR:

Abdominal ultrasound

Abdominal ultrasound can asses if there is a presence of ureteral dilatation. This presence could suggest VUR. However, in many circumstances of VUR of low to moderate, even high severity, the sonogram may be completely normal, thus providing insufficient utility as a single diagnostic test in the evaluation of children suspected of having VUR, such as those presenting with prenatal nephrosis or urinary tract infection.

VCUG

Fluoroscopic voiding cystourethrogram (VCUG) also known as a micturating cystourethrography (MCU), is a fluoroscopic study of the lower urinary tract, using X-rays and contrast. The contrast is introduced into the bladder via a catheter. VCUG is the method of choice for the diagnostic and grading of VUR and also diagnostic of posterior urethral valve (PUV).

ceVUS

Contrast-enhanced voiding urosonography (ceVUS) developed later as VCUG and is a dynamic imaging technique that makes also possible to study the structure of the urinary tract after the administration of intravesical contrast material. Initially, ceVUS was indicated mainly to study vesicoureteral reflux (VUR). However, since the ability of ceVUS to depict the structure of the urethra was demonstrated in both sexes, ceVUS is also used, this depending on the experience of the center, for examination of the entire urinary tract. The main benefit of ceVUS is that it does not use ionizing radiation.

► Early diagnosis in children is crucial as studies have shown that the children with VUR who present with a UTI and associated acute pyelonephritis are more likely to develop permanent renal cortical scarring than those children without VUR. 

TREATMENT

The goal of treatment is to minimize infections, as it is infections that cause kindey scarring and not VUR. There has been a shift toward a more conservative management of VUR with an individualized, risk-lowering approach.The condition may resolve spontaneously but it can persist for many years. The older age, high-grade VUR, other urinary tract and kidney abnormalities, prenatal hydronephrosis, bladder dysfunction, low bladder filling volume at reflux onset, breakthrough UTI and female gender were associated with a lower likelihood of spontaneous VUR resolution.

The management of VUR may be non-surgical (observation, urotherapy, antibiotic therapy), minimally invasive (endoscopic injection) or surgical (ureteral reimplantation).

Non-Surgical Treatment

Observation is suitable only for patients at low risk of kidney injury and in the absence of repeat febrile UTIs. This approach includes regular follow-ups, especially early recognition and treatment of UTIs. The chance of spontaneous resolution of VUR can increase with the effective treatment of BBD (bladder bowel dysfunction, a spectrum of lower urinary tract symptoms associated with bowel complaints). Children who hold their bladder or who are constipated have a greater number of infections than children who void on a regular schedule.

Antibiotic prophylaxis can reduce the incidence of UTIs, but drawbacks such as antibiotic resistance and incomplete adherence mean that this option is not viable for long-term use.

Minimally Invasive Treatment

Endoscopic treatment is a promising alternative to open surgery, especially in the lower grades of VUR. It is performed endoscopically via cystoscopy. A bulking agent is injected into the submucosal, intramural tunnel of the ureter. It elevates the ureteral orifice. This reduces or resolves the VUR.

Surgical Treatment

► When medical management fails to prevent recurrent urinary tract infections, or if the kidneys show progressive scarring the surgical interventions may be necessary.

Open surgery is the gold standard and outperforms other treatments. The ureter is reimplanted, forming a longer segment of ureter in the bladder wall between the bladder mucosa and muscle. The extended segment remains compressed under increased bladder pressure and prevents reflux.

Robot-assisted laparoscopic ureteral reimplantation (RALUR) is a newer technique. Its advantages are minimal invasion, less postoperative pain and shorter hospital stay than conventional open surgery. Its results are as good as those of conventional surgery. The disadvantages are the high cost and the need for specialist skills.