Newborn with marked bilateral hydronephrosis on prenatal US

VCUG of posterior urethral valves
AP image from a voiding cystourethrogram (above) shows bilateral grade 5 vesicoureteral reflux, right greater than left, and a narrow pinecone-shaped bladder in the inferior midline aspect of the image. Lateral image of the urethra taken during the voiding phase of the voiding urethrogram (below) shows marked dilation of the posterior urethra and a thin lucent membrane at the transition zone where the urethra assumes a more normal caliber.

The diagnosis was posterior urethral valves.