Anterior Urethral Injury

Anterior urethral injury involves the bulbar or penile urethra. The commonest cause is blunt straddle injury, which crushes the bulbar urethra against the pubic symphysis.

Other causes are penile fracture with urethral involvement (a minority of penile fractures), penetrating injury (gunshot, stab), iatrogenic injury (balloon inflation in the urethra, instrumentation, endoscopic surgery), self-instrumentation and zipper injury.

The corpus spongiosum gives the anterior urethra a good blood supply, so repair is simpler and outcomes better than for posterior injury.

Pathophysiology. Crush injury contuses or tears the urethra and spongiosum. Extravasated urine and blood are confined by Colles fascia in a butterfly pattern over the perineum and scrotum.

Penile fracture tears the tunica albuginea and may tear the urethra with it. Untreated extravasation leads to infection, abscess, necrotising infection and later stricture.

Severity:

• Contusion: normal urethrogram, blood at the meatus.
• Partial disruption: extravasation with contrast reaching the bladder.
• Complete disruption: extravasation with no contrast passing proximally.

Blood at the meatus (most partial and complete injuries, but absent in some), painful or failed voiding, butterfly perineal haematoma, and penile swelling with deviation. In penile fracture: a snap, immediate detumescence and an aubergine shaped swelling, with blood at the meatus indicating urethral injury. Later: fever, urinary extravasation, abscess and stricture.

• Retrograde urethrography with 20 to 30 mL of water soluble contrast and oblique views, done before any catheter is passed.
• Penile ultrasound defines the tunica defect and haematoma. MRI if ultrasound is unclear.
• Flexible urethroscopy by an experienced operator for suspected partial injury.
• Urine culture and haemoglobin. CT for associated pelvic or abdominal injury.

Differential diagnosis.

• Posterior urethral injury
• Bladder rupture
• Penile fracture without urethral injury
• Rupture of the superficial dorsal vein
• Urethral false passage
• Pre-existing urethral stricture
• Foreign body

• Contusion: observation, with a small silicone catheter for a few days only if voiding fails.
• Partial disruption: suprapubic catheter, or a 12 to 14 Fr silicone urethral catheter passed with urethrographic confirmation, for 7 to 14 days (up to 21 if severe). Perform a pericatheter urethrogram before removal. Most heal, but later stricture can form.
• Complete disruption from blunt bulbar straddle injury: suprapubic diversion and delayed urethroplasty at 3 months or more, because the zone of injury is not defined early.
• Sharp, clean and short injuries (stab, surgical injury, penile fracture) and low velocity gunshot wounds: debridement and early primary end-to-end repair with fine absorbable sutures (4/0 or 5/0), spatulated and tension free, over a 14 to 16 Fr silicone catheter for 14 to 21 days. High velocity injuries and long defects need suprapubic diversion and delayed repair.
• Penile fracture: explore within 24 hours through a circumcising degloving incision, evacuate haematoma, close the tunica albuginea with interrupted inverted absorbable 2/0 or 3/0 sutures, and repair the urethra over a catheter for 7 to 14 days. Avoid intercourse for 4 to 6 weeks.
• Antibiotics: cefazolin 2 g intravenously (3 g if over 120 kg) as a single perioperative dose, or clindamycin 600 mg intravenously once in severe penicillin allergy. Extravasation with infection needs drainage, debridement and ceftriaxone 2 g intravenously once daily with metronidazole 500 mg intravenously every 8 hours. Necrotising infection needs emergency debridement.
• Tetanus prone wounds: tetanus toxoid 0.5 mL intramuscularly if vaccination is incomplete or the last dose was over 5 years ago, and immunoglobulin 250 IU intramuscularly (500 IU if over 24 hours since injury or heavy contamination) when status is unknown or incomplete.

Monitoring. Pericatheter urethrogram before catheter removal, uroflowmetry at 3, 6 and 12 months, and erectile function review. Stricture risk is highest after complete disruption and after delayed treatment of partial injury.

Referral and escalation. Refer to urology for all urethral injuries. Urgent referral for retention, extravasation with sepsis, necrotising infection or penile fracture.