ABSTRACT
A1 C PUVs are the most common congenital anomaly causing bladder outlet obstruction in boys, with an incidence of 1 in 5000 to 1 in 8000 male births. At 5-6 weeks’ gestation, the orifice of the mesonephric duct normally migrates from an anterolateral position in the cloaca to Müller’s tubercle on the posterior wall of the urogenital sinus. The remnants of the mesonephric duct remain as small distinct paired lateral folds termed plicae colliculi. When the insertion of the mesonephric ducts into the cloaca is anomalous or too anterior, the ducts fuse anteriorly resulting in the formation of abnormal ridges called PUVs. Hugh Hampton Young classified posterior urethral valves into three types: Type I are the most common and present in 95% of cases. They are an obstructing membrane that originates at the verumontanum and travels distally to insert in the anterior proximal membranous urethra with an opening present posteriorly at the verumontanum. Type III valves make up the remaining 5% and appear as a membranous diaphragm with a central aperture at the verumontanum, also described as COPUM. Type II valves are non-obstructive and clinically insignificant prominent longitudinal folds of hypertrophied smooth muscle that radiate cranially from the verumontanum to the posterolateral bladder neck. This condition occurs sporadically without any genetic inheritance.
