CHAPTER 43 Urethral Lesions
From distal to proximal, what are the anatomic names of the urethral segments?
• Fossa navicularis
• Penile–pendulous urethra
• Bulbous urethra
• Membranous urethra
• Prostatic urethra
Describe the different types of epithelia lining the male urethra.
• Prostatic and membranous urethra: transitional epithelium.
• Bulbar urethra: squamous epithelium distally and gradually changes to transitional epithelium.
• Penile urethra: simple squamous epithelium.
• Fossa navicularis: stratified squamous epithelium.
What is the average length of the male urethra?
The average length of the urethra from an anatomically normal male is 22 cm (range, 15-29 cm)
What is the lacuna magna?
The dorsal expansion of the fossa navicularis in the glans penis is called the lacuna magna.
What portion of the urethra do Cowper glands and the glands of Littre open into?
Cowper glands open into the membranous urethra, while the glands of Littre open into the dorsal urethra.
What is the specific feature of the male urethral blood supply which is advantageous in planning urethral reconstructive surgery?
The male urethra has a dual blood supply—proximally from the bulbar artery, a branch of the internal pudendal artery, and distally from the dorsal artery of the penis, which is a terminal branch of the pudendal artery. This fact allows for complete excision of diseased segments of the urethra during urethral reconstruction.
What is the name of the deep penile fascia and its attachments?
Buck fascia surrounds the corpus spongiosum and corpora cavernosa. Distally, Buck fascia is connected to the undersurface of the glans at the corona. Proximally, Buck fascia encloses each crus of the corpora cavernosa and the bulb of the corpus spongiosum.
When Buck fascia remains intact after injury to the anterior urethra, what is the expected appearance?
Typically, if Buck fascia remains intact, bruising, hematoma, and swelling will be confined to the penis.
What is the name of the superficial penile fascia and its attachments?
Colles fascia of the perineum attaches laterally to the fascia lata of the thigh, the ischia, and the inferior rami of the pubis. Anteriorly, Colles fascia is continuous with the Dartos layer of the scrotum and Scarpa fascia on the anterior abdominal wall.
How do injuries that violate Buck fascia and leave Colles fascia intact appear?
A butterfly or saddle perineal appearance of a hematoma may be present. In addition, a scrotal hematoma and bruising on the anterior abdominal wall to the level of the clavicles is possible.
What are the most common sites of iatrogenic urethral injury?
The penoscrotal junction and the external urethral meatus are the most common sites of iatrogenic urethral injury.
What is the incidence of urethral injury following pelvic fractures?
Approximately 10% of pelvic fractures are accompanied by urethral injury, whereas a majority of patients with urethral injury will have pelvic fractures. Approximately 10% of patients with posterior urethral injury will also have an accompanying bladder rupture.
What is the most common cause of external urethral meatal stenosis requiring surgical repair?
Lichen sclerosis is the most common cause of meatal stenosis requiring surgical repair.
What is the proper technique for obtaining a retrograde urethrogram (RUG)?
A RUG is obtained by positioning the patient obliquely at 45°, with the bottom leg flexed 90° at the knee and the top leg kept straight. A 12-F Foley catheter is introduced into the fossa navicularis, the balloon inflated with 2 mL saline to prevent dislodgement, the penis placed on gentle traction, and 20 to 30 mL of undiluted water-soluble contrast material is injected with the film exposed while injecting.
How do blunt injuries to the urethra occur?
Blunt urethral injuries typically result from straddle-type trauma incurred after forceful contact of the perineum with a blunt object. Any focused external force, as encountered in falls and vehicular accidents, can crush the immobile bulbous urethra against the inferior pubic symphysis.
A 40-year-old male presents after a motorcycle crash with blood at his meatus. What is the next step in his urinary tract evaluation?
Blood at the meatus is seen in at least 75% of patients after external anterior urethral trauma. No urethral instrumentation should be undertaken until a proper RUG is obtained if meatal blood is present or suspicion of urethral injury exists. If the urethra is in continuity or only partially disrupted, an attempt at placing a well-lubricated Foley catheter should be made.
What other radiologic methods other than a RUG can be employed in evaluating urethral injuries?
Urethral strictures resulting from urethral trauma can also be evaluated by a sonographic urethrogram at the time of delayed repair, but are not typically used in the acute trauma setting. A sonographic urethrogram allows determination of the extent of periurethral fibrosis, spongiofibrosis, and luminal size. This is important because in the case of most urethral strictures, subepithelial spongiofibrosis extends well beyond the grossly identifiable stricture area. MRI can be useful in the evaluation of posterior urethral disruptions.
What is the main continence mechanism in men with complete urethral disruption?
The bladder neck constitutes the main continence mechanism in men with complete urethral disruption.
What are the 2 main principles to be kept in mind during the excision and reanastomosis of urethral strictures?
Excision and reanastomosis should be avoided in pendulous urethral strictures because it can result in shortening of the penile urethra and chordee. A similar situation can result if >2 cm of bulbar urethra is excised and the urethra is not properly mobilized.
What are the most common indications for 2-stage urethral reconstruction?
The most common indications prompting a 2-stage urethral reconstruction are: pan-urethral stricture with a poor and narrowed urethral plate, multiple strictures, presence of urethrocutaneous fistula, periurethral inflammation, lichen sclerosis, or extensive local scarring.
What are the principal advantages and disadvantages of immediate primary urethral reanastomosis versus delayed primary reanastomosis?
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