- Vesicoureteral reflux (VUR) is the abnormal flow of urine from the bladder into the upper urinary tract.
- In the majority of cases, it occurs as a result of a primary maturation abnormality of the vesicoureteral junction or a short distal ureteric submucosal tunnel in the bladder that alters the function of the valve mechanism.
- VUR may be an isolated anomaly or associated with other congenital anomalies such as posterior urethral valves or complete duplication of the urinary tract.
- Reflux predisposes to pyelonephritis because it carries bacteria from the bladder to the upper urinary tract.
- The majority of pediatric patients who develop renal scars after a urinary tract infection have VUR, and higher grades of reflux are associated with an increase in parenchymal scarring.
- Reflux nephropathy is a common cause of renal failure; therefore, it is important that this condition be detected as early as possible to allow prompt prophylactic antibiotic treatment and hopefully reduce the risk of scarring and reflux nephropathy.
- The primary diagnostic procedure for evaluation of VUR is VCUG, which should be performed after the first well-documented urinary tract infection.
- VCUG should be used to document the presence of VUR and to determine the grade of reflux and whether reflux occurs during micturation or during bladder filling.
- Grading of VUR is based on the International Reflux Committee Study. Grade is determined on the basis of the most severe VUR, which usually coincides with the peak of voiding.
- 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.
- 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 recognizing important associated bladder disease (eg, bladder diverticula), difficulty in visualizing the male urethra, and lack of spatial resolution.
 Imaging Findings
International Reflux Committee Study
- Grade I - Reflux into nondilated ureter
- Grade II - Reflux into renal pelvis and calyces without dilation
- Grade III - Reflux with mild-to-moderate dilation and minimal blunting of fornices
- Grade IV - Reflux with moderate ureteral tortuosity and dilation of pelvis and calyces
- Grade V - Reflux with gross dilation of ureter, pelvis, and calyces, loss of papillary impressions, and ureteral tortuosity
Patient #1: VCUG demonstrating bilateral Grade III vesicoureteral reflux
 See Also
 External Links
- Teresa Berrocal, Pedro López-Pereira, Antonia Arjonilla, and Julia Gutiérrez. Anomalies of the Distal Ureter, Bladder, and Urethra in Children: Embryologic, Radiologic, and Pathologic Features. RadioGraphics 2002 22: 1139-1164.