Final answer:
A voiding cystogram with contrast medium is used to demonstrate the male urethra by taking X-ray images during urination, revealing the anatomy and any potential abnormalities.
Step-by-step explanation:
To best demonstrate the male urethra in a voiding cystogram, a specific imaging process is utilized. This diagnostic procedure involves filling the bladder with a contrast medium and then taking X-ray images while the patient urinates. During this process, the entire urethra can be visualized as the contrast medium flows through it. The male urethra, averaging about 20 cm in length, is significantly longer than the female urethra and is divided into four regions: the periprostatic, the prostatic, the membranous, and the spongy or penile urethra. As the patient voids, the contrast delineates the urethral anatomy, highlighting any abnormalities or issues such as strictures, obstructions, or lesions.