Pelvic Fracture Urethral Injury

Pelvic fracture urethral injury is a tear or distraction of the posterior urethra, usually at the membranous urethra or bulbomembranous junction, caused by shearing forces through the pelvic ring.

It occurs in about 4 to 14% of men with pelvic fractures, with a wider reported range of 1 to 25%, and much less often in women. The highest risk is with anterior ring fractures: bilateral pubic rami fractures, symphysis diastasis and straddle patterns.

Typical causes are road traffic collisions, falls from height and crush injuries. In boys the injury often lies higher, at the prostate or bladder neck.

Pathophysiology. The prostate and bladder move with the fractured ring while the membranous urethra is fixed at the urogenital diaphragm, so the urethra tears at its fixed point. A pelvic haematoma forms around the tear and displaces the prostate upward.

Healing is by dense fibrosis with a distraction defect between the two ends, so complete disruption almost always ends in stricture or obliteration.

Severity grades:

• Grade I: contusion or stretch, urethra elongated with no extravasation.
• Grade II: partial disruption, extravasation with contrast reaching the bladder.
• Grade III: complete disruption with a gap under 2 cm, no contrast reaching the bladder.
• Grade IV: complete disruption with a gap of 2 cm or more.
• Grade V: complete disruption with extension into the bladder neck, prostate, vagina or rectum.

Blood at the meatus (the most frequent sign, though absent in a minority), inability to void with suprapubic fullness, butterfly perineal or scrotal haematoma, and a high riding or impalpable prostate on rectal examination (unreliable when haematoma is large). In women, vaginal bleeding, labial swelling and haematuria, with vaginal laceration requiring examination.

Associated injuries are common: bladder rupture in roughly 10 to 20%, rectal injury in about 5%, pelvic vascular bleeding, and abdominal and head injury. Urological assessment follows airway, breathing and circulation.

Haemodynamic instability from pelvic bleeding, blood on the rectal glove or palpable bone fragments (rectal injury), an open pelvic fracture, perineal or vaginal laceration, and gross haematuria with inability to void need immediate escalation.

• Resuscitate and complete the trauma assessment first. Do not pass a urethral catheter when there is blood at the meatus, perineal haematoma or a high riding prostate until urethral injury is excluded.
• Retrograde urethrography: 20 to 30 mL of water soluble contrast with the catheter tip in the fossa navicularis and a 1 to 2 mL balloon, in a 30 degree oblique position. Grade the injury by extravasation and by contrast entering the bladder.
• CT of the pelvis, and CT cystography (retrograde filling with 300 to 350 mL of dilute contrast with post-drain images) for bladder rupture.
• Haemoglobin, crossmatch, creatinine, urine culture.
• At 3 months, combined antegrade study through the suprapubic tract and retrograde urethrography to measure the gap length. MRI helps in complex defects.

Differential diagnosis.

• Anterior urethral injury
• Intraperitoneal or extraperitoneal bladder rupture
• Bladder neck injury
• Rectal injury
• Prostatic injury
• Renal or ureteric injury causing haematuria
• Pre-existing urethral stricture

• Resuscitation, pelvic binder, and control of haemorrhage (angioembolisation or preperitoneal packing) take priority over urological management.
• Urine drainage: suprapubic catheter of 12 to 16 Fr, placed percutaneously under ultrasound control when the bladder is distended, or open at laparotomy.
• Immediate open repair is not advised, because haematoma obscures the anatomy and it carries high rates of impotence and incontinence.
• Primary endoscopic realignment within 1 to 2 weeks in stable patients: a flexible cystoscope is passed from the urethra and the suprapubic tract, a wire is placed across the gap, and a 16 Fr silicone catheter is left for 4 to 6 weeks. A large proportion still develop stricture, but the later repair is often simpler. Evidence is mixed.
• Delayed urethroplasty at 3 months or more after injury, usually 3 to 6 months, when the haematoma has resolved, the fractures have united and the patient is mobile. Perineal anastomotic urethroplasty succeeds in about 90 to 95% in specialist units. Gaps may need corporal splitting, inferior pubectomy or urethral rerouting, and complex defects may need a transpubic or abdominoperineal approach.
• Bladder neck injury, intraperitoneal bladder rupture and rectal injury need immediate laparotomy and repair, with faecal diversion for rectal injury. Extraperitoneal rupture needs repair if pelvic internal fixation is planned.
• Antibiotics: ceftriaxone 2 g intravenously once daily, with metronidazole 500 mg intravenously every 8 hours if there is rectal injury, stopped once wounds are closed and contamination is excluded, usually within 24 to 72 hours.
• Women: urethral tears with vaginal laceration need early primary repair within days.
• Late outcomes: erectile dysfunction in about 20 to 60%, higher after complete disruption and partly caused by the fracture itself, and continence is preserved in most when the bladder neck is competent.

Monitoring. Change the suprapubic catheter every 4 to 12 weeks. After urethroplasty, perform a pericatheter urethrogram at about 3 weeks before removal, uroflowmetry at 3, 6 and 12 months, and assess continence and erectile function.

Referral and escalation. All suspected urethral injuries need urology review, and definitive repair belongs in a reconstructive centre. Urgent escalation for associated bladder neck, bladder or rectal injury, or instability.