What are the two components of the anterior urethra? What marks the border between anterior and posterior urethra?
The penile urethra and the bulbar urethra. The anterior urethra extends to the external sphincter.
What are the two components of the posterior urethra?
The prostatic urethra (more upstream) and the membranous urethra.
Normal retrograde urethrogram (RUG), followed by a normal voiding cystourethrogram (VCUG).
The penis is postioned at approximately the 10 o'clock position. The round opaque structure in the distal penis is the inflated Foley balloon. The Foley catheter tip is faintly radiopaque, but can be better seen as a filling defect after administration of contrast.
There is no stricture or leak of the urethra. Contrast pauses at the external sphincter, with good opacification of the penile and bulbar urethra.
The voiding urethrogram evaluates the posterior urethra. The Foley balloon is advanced into the bladder and contrast is instilled until the bladder is dilated. The bladder should be so dilated, that the patient "feels like he absolutely needs to pull off to the side of the road so he can urinate". The Foley is then removed and the patient is encourage to urinate.
Images are obtained of the open posterior urethra. As this is not a dedicated cystogram, imaging the bladder is a secondary concern. In this case, there is no stricture or leak.