Urinary: Urethra Flashcards
What are the anatomical segments of the male urethra?
- Anterior (penile and bulbar segments)
- Posterior (membranous and prostatic)
Fossa navicularis
Verumontanum (an ovoid mound along the posterior wall of the prostatic urethra that receives the ejaculatory ducts and also contains the prostatic utricle)
Prostatic utricle
A embryologic mullerian duct remnant located on the verumontanum of the prostatic urethra
Which portions of the urethra are best evaluated with a retrograde urethrogram?
The anterior urethra (penile and bulbar segments)
Note: A voiding/anterograde urethrogram is usually done to visualize posterior urethral problems. It is possible to opacify the entire urethra during a retrograde urethrogram, but this requires applying enough pressure to overcome the normal spasms that occur in the urethra.
The purple portion of urethra is the…
Prostatic urethra
The green part of the urethra is the…
Membranous urethra
The red part of the urethra is the…
Bulbar urethra
The blue part of the urethra is the…
Penile urethra
How can you identify the bulbar-membranous junction on a retrograde cystourethrogram?
Look for the cone shaped appearance of the proximal bulbar urethra
Note: This is an important junction because it separates the anterior urethra from the posterior urethra.
- Prostatic urethra
- Membranous urethra
- Bulbar urethra
- Penile urethra
How can you approximate the bulbar-membranous junction of a retrograde urethrogram if you can’t opacify the urethra?
Draw a line connecting the inferior margins of the obturator foramina
How can you differentiate the bulbar and penile urethra on a retrograde urethrogram?
There should be a turn at this point due to the penis changing angles as it becomes an external structure
Blood in the urethral meatus s/p trauma…
Possible urethral injury, recommend a retrograde cystourethrogram
Common causes of traumatic urethral injury
- Straddle injury, such as smash into bicycle seat (usually an anterior urethral injury)
- MVC or other more intense trauma (usually a posterior urethral injury with associated pelvic fractures/bladder rupture)
Male urethral injury classification
- Type 1(stretched urethra, normal urethrogram)
- Type 2 (tear of the membranous urethra)
- Type 3 (tear of the membranous and bulbar urethra)
- Type 4 (Bladder injury extending into the prostatic urethra)
- Type 5 (anterior tear of the bulbous urethra)
What is the most common type of urethral injury?
Type 3 (tear of the membranous and bulbar urethra)
What is the difference between a type 2 and a type 3 urethral injury?
Both involve the membranous urethra, but type 3 also tears the urogenital diaphragm and involves the bulbous urethra
Which ureathra injury types are associated with incontinence?
Types 2, 3, and 4
Urethral injury type with extraperitoneal contrast, but no perineal contrast on retrograde urethrogram?
Type 2 (tear of the membranous urethra)
Urethral injury type with extraperitoneal and perineal contrast on retrograde urethrogram…
Type 3 (tear of the bulbous and membranous urethra)
What is the site of male urethral injury during a straddle injury?
The bulbous urethra
Note: A straddle injury is when the urethra is smashed against the pubic symphysis, usually from the pts groin smashing against their bicycle crossbar.
How can you differentiate a straddle injury from a gonococcal urethral stricture?
Straddle injuries produce short segment strictures of the proximal bulbous urethra
Gonococcal strictures are usually long segment strictures of the distal bulbar urethra
Long segment, irregular, beaded narrowing of the distal bulbar urethra, suggestive of gonococcal urethral stricture
Note: The Cowper glands are also opacified.
Why were pancreatic transplants often associated with urethral injury?
Pancreatic transplants used to drain to the bladder, and leakage from urethral injury occurred in ~5% of pts
Retrograde urethrogram
Think condyloma acuminatum
Note: Multiple small filling defects. Instrumentation (including retrograde urethrogram) is not recommended due to the risk of retrograde seeding.
Retrograde urethrogram
Urethrorectal fistula
Note: This is usually post radiation (especially brachytherapy).
Retrograde urethrogram
Urethral diverticulum
Note: This is usually due to long term foley placement.
What is the most common cancer of the male urethra?
Squamous cell carcinoma (80%)
Note: This is not true for the prostatic urethra, where 90% of cancers are transitional cell carcinoma.
What is the most common cancer of the prostatic urethra?
Transitional cell carcinoma (90%)
Note: This is unlike the rest of the urethra, where squamous cell carcinoma is much more common (80%). Think of the prostatic urethra as being part of the bladder.
What is the most common cancer of a male urethral diverticulum?
Adenocarcinoma (almost always)
Note: Non-diverticular urethral cancers (outside the prostatic urethra) are usually squamous cell carcinoma.
Female urethral diverticulum
Note: Urethral diverticula are more common in females due to recurrent UTIs.
Think urethral diverticulum
Urethral diverticulum
Note: This is the “female prostate” sign.
What is the most common cancer of a female urethral diverticulum?
Adenocarcinoma (60%)
Bladder mass with calcifications…
Think squamous cell carcinoma (possibly in the setting of schistosomiasis infection)
Adenocarcinoma is a rare collecting system/bladder cancer, except in…
- Urachal remnants
- Bladder exstrophy
- Urethral diverticula
