Anterior Urethral valve

Ian Morley, MD

Martha Saker, MD

Keywords

1745, fluoroscopy, genitourinary, VCUG


Publication Date: 2011-07-27

History

16 year old male presents with post-void dribbling.

Findings

Multiple fluoroscopic images demonstrate mild dilatation of both the prostatic and membranous urethra, with an abrupt transition to a persistently narrowed bulbous urethra.

Diagnosis

Anterior Urethral Valve

Discussion

Anterior urethral valves are rare congenital anomalies that cause lower urinary tract obstruction in children. They can occur as an isolated entity or in association with a proximal diverticulum. The embryologic development of anterior urethral valves remains unclear. Various proposed etiologic mechanisms include an abortive attempt at urethral duplication, failure of alignment between the proximal and distal urethra, imbalanced tissue growth in the developing urethra resulting in a remnant of excess tissue acting as a valve, and congenital cystic dilatation of periurethral glands resulting in a flaplike valve. Anterior urethral valves may be found anywhere in the anterior urethra. 40% of the valves are located in the bulbar urethra, 30% at the penoscrotal junction, and 30% in the pendulous urethra.

The clinical manifestation of anterior urethral valves is highly variable and depends on patient age and degree of obstruction. Findings may range from minimal to severe obstruction with bilateral severe hydroureteronephrosis, endstage renal disease, and even bladder rupture.

VCUG is the diagnostic modality of choice for anterior urethral valves. Typically, the urethra appears dilated proximal to the valve and narrowed distal to it. A valve may appear as a linear filling defect along the ventral wall, or it may be indicated by a dilated urethra ending in a smooth bulge or an abrupt change in the caliber of the dilated urethra. In addition to demonstrating a lesion in the urethra, VCUG may also reveal an associated anomaly. VUR has been reported in one-third of cases and upper tract deterioration in one-half. Endoscopic examination of the urethra may help confirm the diagnosis.

References

  1. 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, September 2002 22:1139-1164.

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