. Abdominal
ultrasound is of some benefit, but not diagnostic. Features that suggest posterior urethral valves are bilateral hydronephrosis, a thickened bladder wall with thickened
smooth muscle trabeculations, and bladder
diverticula.
Voiding cystourethrogram (VCUG) is more specific for the diagnosis. Normal
plicae circularis are variable in appearance and often not seen on normal VCUGs. PUV on voiding cystourethrogram is characterized by an abrupt tapering of urethral caliber near the
verumontanum, with the specific level depending on the developmental variant.
Vesicoureteral reflux is also seen in over 50% of cases. Very often the posterior urethra maybe dilated thus making the abrupt narrowing more obvious. the bladder wall may show trabeculations or sacculations or even diverticuli. Diagnosis can also be made by
cystoscopy, where a small camera is inserted into the urethra for direct visualization of the posteriorly positioned valve. A limitation of this technique is that posterior valve tissue is translucent and can be pushed against the wall of the
urethra by inflowing irrigation fluid, making it difficult to visualize. Cystoscopy may also demonstrate the bladder changes. Centers in Europe and Japan have also had excellent results with cystosonography, although it has not been approved for use in the United States yet.
Classification Posterior urethral obstruction was first classified by H. H. Young in 1919. The
verumontanum, or mountain ridge, is a distinctive landmark in the
prostatic urethra, important in the systemic division of posterior valve disorders: • Type I - Most common type; due to anterior fusing of the
plicae colliculi, mucosal fins extending from the bottom of the verumontanum distally along the prostatic and membranous urethra • Type II - Least common variant; vertical or longitudinal folds between the verumontanum and proximal
prostatic urethra and bladder neck • Type III - Less common variant; a disc of tissue distal to verumontanum, also theorized to be a developmental anomaly of congenital urogenital remnants in the bulbar urethra Dewan has suggested that obstruction in the posterior urethra is more appropriately termed congenital obstructions of the posterior urethral membrane (COPUMs), a concept that has come from an in-depth analysis of the historical papers, and evaluation of patients with a prenatal diagnosis that has facilitated video recording of the uninstrumented obstructed urethra. The congenital obstructive lesions in the bulbar urethra, named Type III Valves by Young in 1919, have been
eponymously referred to as Cobb's collar or Moorman's ring. For each of the COPUM (Posterior Urethra) and Cobb's (Bulbar Urethra) lesions, the degree of obstruction can be variable, consistent with a variable expression of the embryopathy. The now nearly one hundred year old nomenclature of posterior urethral valves was based on limited radiology and primitive endoscopy, thus a change COPUM or Cobb's has been appropriate. ==Treatment==