Virtual Hospital: Radiology Resident Case of the Week: Vesicoureteral reflux

Radiology Resident Case of the Week

Vesicoureteral reflux

November 28, 1996

Jeff Van Beek
Peer Review Status: Not reviewed

Clinical Sx:
Frequent urinary tract infections, flank pain, fever. Mild to moderate reflux usually disappears spontaneously after treatment for urinary tract infection and over a period of years. Only more severe reflux is likely to produce progressive renal damage, almost always before 5 years of age.

Etiology/Pathophysiology
Vesicoureteral reflux (VUR) may be primary or secondary. Primary VUR is most likely the result of maldevelopment of the ureterovesical junction (UVJ). Gaping ureteral orifices with short intramural segment are present. It is both congenital and familial, and has a tendency to resolve with increasing age. Secondary causes may be associated with a number of diseases that affect the anatomy of the UVJ. These include: diverticulum at UVJ (Hutch diverticulum), increased intravesical pressure (neurogenic bladder, bladder outlet obstruction from posterior urethral valves), and ureteral duplication anomalies.

Pathology:
Reflux of infected urine into the renal pelvis and collecting tubules may cause focal or diffuse acute pyelonephritis, the end result of which is a scar. Following significant renal mass reduction by scarring, progressive renal insufficiency may develop. This clinical entity is called refluxing nephropathy.

Miscellaneous
As seen on voiding cystourethrogram (VCUG), VUR is classified as:

Grade I reflux only into ureter

Grade II reflux into collecting system, without dilation

Grade III reflux into collecting system, with mild dilation

Grade IV reflux into collecting system, with moderate dilation

Grade V reflux into collecting system, with severe dilation, and significant calyceal blunting.

Imaging
VCUG - Initial test to assess for presence and degree of reflux. Also evaluate bladder mucosa and anatomy and functioning of urethra.

Radionuclide cystogram - With less anatomic detail than a VCUG, it is not recommended initially. However, with significantly less radiation exposure and a high sensitivity for reflux, it is useful as a follow-up test.

Other Radiological Findings:
1. Renal Scar - normal parenchymal thickness is drastically reduced in the affected areas. Scarring is common in the upper poles.

2. Calyceal clubbing - scar involves both cortex and medulla so that papillary impression eventually disappears, leaving a "blunted" calyx.

3. Pseudotumor - remaining unscarred renal parenchyma may undergo compensatory hypertrophy. These enlarged portions may distend the renal outline and adjacent calyces and thus mimic a mass.

DDX

Key references
Amis, E.S., and Newhouse, J.H. Essentials of Uroradiology. 1991. pp 245-255.
Barbaric, Z.L. Principles of Genitourinary Radiology. 2nd ed. 1994. pp 138-140.

ACR Code
825.85

Keywords:
vesicoureteral reflux, refluxing nephropathy, ureterovesical junction

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