Teaching Case

A 50-year-old male, a prospective renal transplant recipient is a known case of end stage renal disease. Retrograde Urethrography (RGU) and Voiding cystourethrography (VCUG) were performed as part of urological evaluation. Patient had no history of poor urinary stream and straining during micturition.

Retrograde Urethrography shows a linear incomplete filling defect in the penile urethra arising from the ventral wall of penile urethra.
VCUG showed mild dilatation of the anterior urethra ending in a smooth bulge. The urinary bladder showed smooth outline with no vesico-ureteric reflux (VUR) or urinary bladder diverticulum.

Urethral valves are infravesical congenital anomalies, with the posterior urethral valve (PUV) being the most prevalent one. Though anterior urethral valves are a rare congenital anomaly, it is the second most common cause of congenital urethral obstruction in boys. These can occur singly or in combination with a proximal urethral diverticulum. Various proposed hypotheses are incomplete fusion of a segment of the urethral plate, abortive attempt at urethral duplication, failure of alignment between the proximal and distal urethra, imbalanced tissue growth in the developing urethra leading to a remnant of excess tissue acting as a valve, and congenital cystic dilatation of periurethral glands leading to a flap-like valve[1]

During micturition, urine fills the ventral urethral sacculation and/or diverticulum proximal to the valve, elevating the lip of the valve and pressing it against the dorsal wall of the urethra, limiting the flow of urine. Bulbar urethra is the most common site for AUV (40%) followed by penoscrotal junction(30%) and pendulous urethra(30%)[2]. AUV in the fossa navicularis also have been reported.

Patients present with penile swelling during micturition, caused by dilatation of the saccule and/or obstructive dilatation of the urethra. Infants may present with urosepsis and/or renal insufficiency if the valve is obstructing.

VCUG is the diagnostic modality of choice in the diagnosis of anterior urethral valve. On imaging, It is a posteriorly directed semilunar fold and arises from the anterior urethra. It can mimic an anterior urethral diverticulum, but the posterior lip is absent in the valve[3].

Based on the degree of obstruction, there may be dilation or elongation of posterior urethra and portion of anterior urethra, a thickened trabeculated bladder, a hypertrophied bladder neck and VUR. The urethra appears dilated proximal to the valve and narrowed distal to it on VCUG. On RGU, it is demonstrated as a linear filling defect along the ventral wall, or it may show a dilated urethra ending in a smooth bulge or an abrupt change in the caliber of the dilated urethra on VCUG[4]. Associated anomalies like diverticulum, megacystis, VUR may be noted.

Transurethral valve ablation with the help of a pediatric resectoscope is the treatment of choice for AUV[5]. Various complications of endoscopic resection include stricture, urethro-cutaneous fistula, and persistent urethral dilatation. Other reported methods include open urethrotomy and excision of the valve, segmental urethrectomy of the valve-bearing area with a primary end-to-end anastomosis[6].