Vesicoureteric reflux (VUR) is the term for abnormal flow of urine from the bladder into the upper urinary tract and is typically a problem encountered in young children.
For grading of vesicoureteric reflux, please refer to vesicoureteric reflux grading.
The incidence of UTI is 8% in females and 2% in males 2. Out of all UTI affected children, incidence of VUR is at ~ 25-40%.
Reflux from the bladder into the upper urinary tract predisposes to pyelonephritis by allowing entry of bacteria to the usually sterile upper tract. As such the diagnosis is first suspected after a urinary tract infection in a young child.
Vesicoureteric reflux may be an isolated abnormality or associated with other congenital anomalies including:
Vesicoureteric reflux is, in the majority of cases, the result of a primary maturation abnormality of the vesicoureteral junction resulting in a short distal ureteric submucosal tunnel. As a result the normal pinch-cock action of the VUJ when bladder pressure increases during micturition is impaired, allowing urine to pass retrogradely up the ureter.
The primary diagnostic procedure for evaluation of vesicoureteric reflux is a voiding cystourethrogram (VCUG), which however requires bladder catheterisation and distention of the bladder. This typically causes significant discomfort to the patient, requiring immobilisation of one form or another. In addition as it is a fluoroscopic examination it requires ionising radiation, the dose of which varies greatly depending on the equipment and technique used.
As such other methods for assessing vesicoureteric reflux are being evaluated. These include:
- nuclear medicine studies
- MR voiding cystography 3
Voiding cystourethrogram (VCUG)
Voiding cystourethrogram (also known as micturating cystourethrogram - MCU) should be performed after the first well-documented urinary tract infection up to the age of 6 years 3. VCUG should evaluate:
- presence and grade of VUR
- whether reflux occurs during micturition or during bladder filling
- presence of associated anatomical anomalies
Routine ultrasound is usually also performed (in addition to VCUG) to assess the renal parenchyma for evidence of scarring or anatomic anomalies.
Additionally ultrasound has been investigated as a replacement for traditional fluoroscopic voiding cystourethrogram, by assessing the distal ureters during bladder filling, using micro-bubbles 4.
Reflux can also be graded, although less precisely, with nuclear cystography. There is no universally accepted grading system for nuclear cystography, with most radiologists simply using the terms mild, moderate, and severe 2.
Advantage of nuclear cystography is the lower radiation dosage, which makes it an excellent tool for screening female patients and for following up patients of both sexes.
Disadvantages of nuclear cystography are difficulty in recognising important associated bladder disease (e.g. bladder diverticula), difficulty in visualising the male urethra, and lack of spatial resolution.
MR voiding cystourethrogram protocols are still being developed but have the advantage of not having ionising radiation and of simultaneously imaging the renal parenchyma 3.
Treatment and prognosis
If reflux is unrecognised and significant, not only are patients likely to develop recurrent urinary tract infections, but there infections can result in renal scars and eventually renal failure (reflux nephropathy).
Prompt prophylactic antibiotic treatment in low grades and surgical reimplantation in higher grades are aimed at reducing the risk of scarring and reflux nephropathy.
- 1. Berrocal T, López-pereira P, Arjonilla A et-al. Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features. Radiographics. 22 (5): 1139-64. Radiographics (full text) - Pubmed citation
- 2. Lim R. Vesicoureteral reflux and urinary tract infection: evolving practices and current controversies in pediatric imaging. AJR Am J Roentgenol. 2009;192 (5): 1197-208. doi:10.2214/AJR.08.2187 - Pubmed citation
- 3. Vasanawala SS, Kennedy WA, Ganguly A et-al. MR voiding cystography for evaluation of vesicoureteral reflux. AJR Am J Roentgenol. 2009;192 (5): W206-11. doi:10.2214/AJR.08.1251 - Pubmed citation
- 4. Kessler RM, Altman DH. Real-time sonographic detection of vesicoureteral reflux in children. AJR Am J Roentgenol. 1982;138 (6): 1033-6. AJR Am J Roentgenol (abstract) - Pubmed citation