VUR represents an abnormal retrograde flow of urine towards the ureter or even the kidneys.
This condition is associated with an increased risk of recurrent urinary tract infection (UTI) and renal scarring1.
The prevalence of VUR in children is between 0.4% and 1.8%.
It is found in 25% to 50% of children presenting with urinary tract infection,
in 27.4% of siblings of patients with
diagnosed VUR and in 3% to 19% of infants with documented prenatal urinary tract anomalies 2,3,4.
According to Darge,
the reflux is graded using ce-VUS into five grades,
based on the degree of pelvicalyceal and ureteral dilatation (Table 1) 5.
Its severity is correlated with the prognosis and the therapeutic decision (medical or surgical).
Table 1.
Grading of VUR in ce-VUS
Grade
|
Definition
|
I
|
Microbubbles only in the ureter
|
II
|
Microbubbles in the renal pelvis; no significant renal pelvic dilatation
|
III
|
Microbubbles in the renal pelvis + significant renal pelvic dilatation + moderate calyceal dilatation
|
IV
|
Microbubbles in the renal pelvis + significant renal pelvic dilatation + significant calyceal dilatation
|
V
|
Microbubbles in the renal pelvis + significant renal pelvic dilatation and calyceal dilatation + loss of renal pelvis contour + dilated tortuous ureters
|
The diagnostic modalities available for identifying VUR include: X-ray voiding cystourethrography (VCUG),
radionuclide voiding cystography (RNC),
contrast-enhanced voiding ultrasonography (ce-VUS) and magnetic resonance voiding cystourethrography (MRVCUG) 4,8,
9,10.
VCUG has been the gold standard for the investigation of VUR for decades,
however it involves bladder catheterization with intravesical administration of radiographic contrast and exposure to ionizing radiation.
RNC is a similar procedure,
involves less radiation exposure,
but it has lower anatomical resolution compared to VCUG 11,4.
MRVCUG represents a new,
non-irradiating diagnostic technique with enhanced resolution and it has the possibility to obtain 3D images.
Disadvantages of this method include false positive or false negative results in cases of low/mild grade VUR,
the need for IV sedation,
long examination time,
high costs and limited availability of MRI scanners8.
ce-VUS is a real-time imaging modality for VUR approved by the Food and Drug Administration (December 2016) and by the European Medicines Agency for the European Union (June 2017) 12.
By using the second-generation ultrasound contrast agent (SonoVue®) the sensitivity of reflux detection had increased to 80-100%,
the specificity to 77-97% and the reflux detection rate was with 10% higher compared to VCUG 12,13,
14.
Recently,
a debate has started regarding if the ALARA concept and the Image Gently campaign should end.
It is proved that children are vulnerable to radiation-induced cancers at high-dose radiation only and there are no relevant studies regarding the effects of low-dose radiation exposures on cancer in general population.
The severity of adverse health effects at medical imaging doses is now questionable and until these risks are reframed,
we should use the ionizing radiation justified,
in the appropriate amount to accomplish the specified medical task 15,16,17,18.
ce-VUS is a reliable and a safe procedure for the detection of VUR with very low or absent adverse events reported.
The few minor adverse events were related to the minimally invasive procedure of bladder catheterization itself 9,19.
Indications for ce-VUS: single kidney,
antenatal pelvicalyceal dilatation or other renal and urogenital tract anomalies,
urinary tract infections,
bladder rupture,
follow-up of known VUR under conservative management,
follow-up of surgically corrected VUR,
siblings with VUR 19,20.
A recent study revealed that series of conditions like renal dysplasia,
uroepithelial thickening (wall thickening ≥1 mm),
urinary tract duplication,
are associated with high-grade VUR 21.
The treatment of children with VUR should be individualized.
After the diagnosis of VUR (unilateral or bilateral) all the children receive antibiotic prophylaxis to prevent UTIs and they are followed for at least one year.
Low-grade reflux is resolved with medical treatment in 50% of cases after about 3 years,
while high-grade reflux requires a combined management (medical and surgical).
The surgical options are: laparoscopic/open surgery with ureteral re-implantation and endoscopic correction of VUR using bulking agents (dextranomer/hyaluronic acid copolymer) 6,7.