LAUSR

Posterior urethral valves refer to a male-only congenital abnormality characterized by a membrane in the posterior portion of urethra resulting from the fusion or prominence of plicae colliculi in the verumontanum region that can lead to varying degrees of urinary obstruction [1]. Ultrasound plays an important role in characterizing this condition, revealing a classic configuration known as the keyhole sign: dilatation of the bladder and hypertrophy of the walls producing a rounded shape, accompanied by dilation of the proximal portions of the urethra, creating a keyhole-like contour (Figs. 1, 2) [2]. This finding also can be seen with prenatal ultrasonography, though with variable accuracy [3]. A similar appearance can be identified by voiding cystogram studies, which would depict a thickened and dilated bladder, associated with a dilated proximal urethra and a normal distal urethra (Fig. 3).