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I am Dr. Todd Brandt. I am a urologist. 

These are words I couldn't have imagined myself saying as I was growing up thinking about medicine as a career. 

And I have been asked many, many times why I went into urology as a medical specialty. In this podcast I attempt to explain how I got here. Why did I choose urology as a specialty? Why do I like it? Why, if you are someone with a urinary tract, should you care? Get it? Why Urology.

This podcast is a personal experiment in medical audio content. I make the obvious disclaimer that this is not medical advice. You should be going to your own physician for that.

These episodes are meant to educate, entertain, inspire or inform you in some way with urology as the launching point for each episode. Each episode is varied in format and length as I have experimented with content. 

Listen, follow, share, rate, review, repeat...you know what to do.

If you have kidney stones, or prostate cancer, or another urologic health concern this podcast may help you.

If you have a loved one with any urologic health concern this podcast may help you. 

If you are someone who has asked, "How does my bladder do it's thing?", this podcast may help you.

If you make urine, or even if you don't, this podcast may help you.

Thank you for listening to this podcast. I do appreciated any feedback I get so please reach out to me at the link provided on this website. 

Be well,

Dr. Todd Brandt

Oct 16, 2021

The urethra is a crucial component of genitourinary system in the male, serving both as a way to get urine out of the body as well as to get semen from the prostate and ejaculatory ducts out of the body during ejaculation.

We tend to think of the urethra as just a passive channel during urination, but the urethra is dynamic during ejaculation.

We also tend to think of the male urethra is a single structure, again just a tube that connects the bladder to the outside world, beginning within the bladder wall and ends in the distal glans of the penis. But the urethra is composed of a heterogeneous series of segments along its average length of about 20 cm. Each segment has unique anatomy and physiology that help to serve a specific function.

The four segments are the prostatic, membranous, bulbous and penile urethra.

We tend to think of the urethra as just a straight tube, but it is not. If a man is standing with the penis in a flaccid state and we could see through him to look at the urethra we would see that the urethra forms an S shape as urine travels from the bladder and out to through the four segments of the urethra.

Let’s start at the top.

The urethra begins as the bladder enters the prostate. For about one centimeter or so the bladder and the urethra come together as the urethra is embedded into bladder and is lined by transitional epithelium.

 

Next comes the true prostatic urethra is that portion of the urethra that is completely encompassed within the prostate gland itself. The urethra at this point is actually lining the prostate gland. This 3-4 cm length of urethra (depending on size of prostate) is generally the widest part of the male urethra, surrounded by the glandular and stromal tissue of the periurethral zone of the prostate. During cystoscopy we see the urethra widen here as we pass the scope, and often we simply refer to it as the prostate rather than the urethra.

Because the prostate is responsible for semen production and the prostatic urethra is where semen is deposited prior to ejaculation the prostatic urethra contains the urethral crest, seminal colliculus, prostatic utricle (or verumontanum), and the orifices of the prostatic ducts.

The kind of pathology we can see here the prostatic urethra is generally limited to what is happening within the prostate itself, benign hyperplasia or prostate cancer, and how that impacts the urethral channel. But the urethra here is lined by urothelial transitional cells and can also get the same kind of cancer as bladder cancer, which is difficult to treat if it invades the prostatic ducts, so we must be careful to identify any tumor development in patients with bladder or other urothelial cancers to make sure we are not missing any urothelial tumors within the prostatic channel.

Travelling from the bladder outward, after the prostatic urethra comes the membranous urethra

The membranous urethra is that part of the urethra which is surrounded by the urinary sphincter muscle of the pelvic floor and the facial layers of the perineum.

This segment of the urethra is short, typically just 1.5 centimeters in length or so, a fairly short segment that we rely on to hold our urine and keep us dry.  The membranous urethra begins immediately outside of the prostate and ends just prior to entering the bulb of the penis and the bulbous urethra. 

The lining of the urethra changes within the membranous urethra. The urothelium changes into pseudostratified columnar epithelium, with cells that are more elongated in shape, and look like they are in layers, but they are not.

Pathologically the membranous urethra is susceptible to shearing forces from pelvic trauma. A disruption of the membranous urethra at the level of the sphincter is a difficult injury to manage and treat and can impact a man’s ability to control the urine if the sphincter is permanently damaged.

After we exit the perineum and the membranous urethra we get to the bulbous urethra.  Remember we talked about the urethra being an S shape? Here is the first curve of the S.  the urethra turns at this point to run along the perineum as the bulbous urethra.

The bulbous urethra is that portion of the urethra surrounded by the bulbospongiosus muscle and the corpus spongiosum. The lining remains pseudostratified columnar epithelium.

Congenital urethral strictures can occur in this portion of the urethra.  This portion of the urethra is also susceptible to straddle injury.

Because the male urethra is a long structure that passes through several compartments in the body and therefore, receives blood supply and nerve innervation from several sources. The male urethra receives blood supply from the inferior vesical artery, bulbourethral artery, and the internal pudendal artery.  The venous drainage parallels the arterial supply.

The sympathetic, parasympathetic and visceral innervation to the male urethra gets delivered through the prostatic plexus. 

The lymphatic drainage is different for different parts of the urethra. The prostatic and membranous urethra drain to the obturator and internal iliac nodes. Lymphatic drainage from the spongy urethra drains to the deep and superficial inguinal nodes. The different lymphatic drainage has implications in cases where we find cancer in terms of which lymph nodes we need to look at to check for recurrence.

The last portion of the urethra is the penile urethra. Here is the second curve of the S with the penis in the flaccid state. Typically around 15 cm in length the penile urethra is immediately surrounded by the corpus spongiosum and the pseudostratified columnar epithelium changes in the terminal portion just before the meatus to become stratified squamous epithelium. The penile urethra widens in the glans of the penis, forming the fossa navicularis.

The penile urethra ends at the urethral meatus in the glans penis. The urethral meatus is typically a wide portion of the urethra but is susceptible to injury or inflammation which can lead to stenosis and a potential final spot for obstruction.

Reach out to me with comments, questions, or concerns at whyurologypodcast.com.