ANTERIOR URETHRAL INJURIES

Anterior urethral injuries : These injuries are uncommon.
History and examination
The patient usually presents with difficulty in passing urine and frank haematuria in the context of a straddle injury. Blood may be present at the end of the penis and a haematoma around the site of the rupture. If Buck's fascia has been ruptured (the deep layer of the superficial fascia of penis), urine and blood track into the scrotum causing swelling and a  butterfly wing  pattern of bruising, reflecting the anatomical attachments of Colles  fascia the membranous layer of the superficial fascia of the groin and perineum.

Confirming the diagnosis and subsequent management
Retrograde urethrography delineates the extent of urethral injury.
Extravasation of urine can create a collection of urine around the urethra (a urinoma) and generates an inflammatory reaction, with subsequent stricture formation. Superadded infection can lead to abscess formation, which may burst onto the surface of the skin leading to a urethrocutaneous fistula. More rarely, Fournier's gangrene supervenes. Urinary diversion (urethral or suprapubic catheter) prevents further extravasation of urine, and antibiotics may reduce the likelihood of superadded infection.

Anterior urethral contusion
Typical history: blood at meatus, no extravasation of contrast on retrograde urethrogram. Pass a small gauge urethral catheter (12 Ch in an adult) and remove a week or so later.

Partial rupture of anterior urethra
Leak of contrast from urethra with retrograde flow into bladder. Most can be managed by a period of suprapubic urinary diversion. 70% heal without stricture formation (primary closure can be difficult because of oedema and of haematoma at site of injury and can convert a short area of urethral injury into a longer one). Give a broad spectrum antibiotic to prevent infection of extravasated urine and blood. If a voiding cystogram 2 weeks later confirms urethral healing, remove suprapubic catheter. If contrast still extravasates, leave it in place a little longer.

Suprapubic catheterization (percutaneously) is preferred over urethral catheterization because a partial rupture can be converted to a complete rupture. If the bladder cannot be palpated, such that a suprapubic catheter cannot safely be inserted, then perform open suprapubic cystostomy (under general anaesthetic).

Complete rupture of anterior urethra
Leak of contrast from urethra on retrograde urethrogram, no filling of the posterior urethra or bladder. The urethra may either be immediately repaired (if a surgeon with sufficient experience is available) or a suprapubic catheter can be placed with delayed repair.

Penetrating partial and complete anterior urethral injuries
Knife or gunshot wound: primary (i.e. immediate) repair may be carried out, if a surgeon experienced in these techniques is available; if not, suprapubic diversion and subsequent repair by an appropriate surgeon.
Immediate surgical repair of anterior urethral injuries is only done in the context of penile fracture or where there is an open wound.

The anatomical explantation for  butterfly wing  pattern of bruising in anterior urethral rupture
Fascial layers of penis from superficial to deep:
- penile skin
- superficial fascia of the penis (= dartos fascia) continuous with the membranous layer of the superficial fascia of the groin and perineum (= Colles  fascia)
- Buck's fascia (= the deep layer of the superficial fascia)
- deep fascia of the penis (the tunica albuginea) which covers the two dorsal rods of erectile tissue, the corpora cavernosa, and the ventrally located corpus spongiosum which surrounds the urethra.

If Buck's fascia is intact, bruising from a urethral rupture is confined in a sleeve-like configuration, along the length of the penis. If Buck's fascia has ruptured, the extravasation of blood and thus the subsequent bruising, is limited by the attachments of Colles  fascia which forms a  butterfly  like pattern in the perineum and is continuous in the upper abdomen and chest with Scarpa's fascia.

How to perform a retrograde urethrogram
- Aseptic technique.
- Urografin 150 (sodium amidotrizoate and meglumine amidotrizoate), but other contrast agents can be used.
- Position the patient at an oblique angle (bottom leg flexed at the hip and knee).
- A 12 Ch catheter is placed in the fossa navicularis of the penis 1 - 2cm from the external meatus, with the catheter balloon with 2ml of water or with a penile clamp applied to prevent contrast spilling out of the urethra and to hold the catheter in place.
- Continuous screening (fluoroscopy) is done as contrast is instilled until the entire length of the urethra is demonstrated. Remember, as the urethra passes through the pelvic floor (the membranous urethra) there is a normal narrowing, and similarly the prostatic urethra is narrower than the bulbar urethra.