There are two true statements here. First, the prostate gland encircles the urethra. It circles around the first part of the urethra, the prostatic urethra. This is why urinary retention is one symptom of prostatic hypertrophy--if the prostate is enlarged, it may close around the urethra, occluding this passage and preventing urine from exiting the bladder. The prostate gland is also extraperitoneal. Remember: the rectovesicular pouch, a fold of peritoneum that hangs between the bladder and rectum, is the lowest extent of the peritoneal cavity in males.
But, the prostate is found on the posterior side of the bladder, below the point where the peritoneal membrane created this fold. So, it is an extraperitoneal organ. The lobes of the prostate are: anterior, posterior, lateral, and middle. Finally, the prostate would not be imaged using an intravenous urogram. In an intravenous urogram, a patient is given IV contrast, and radiographic images are taken as the contrast is excreted, passing through the kidneys, ureters, and bladder. Since the prostate is not part of this excretory pathway, it would not be viewed through this method.
