Bulbar urethra rupture
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bulbar urethra rupture injury anatomy diagram
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anterior urethral injury straddle perineum extravasation urine
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Bulbar Urethra Rupture
Anatomy Recap
The urethra is divided into posterior (prostatic + membranous) and anterior (bulbar + penile) segments. The bulbar urethra is the proximal portion of the anterior urethra, lying in the perineum where it curves over the perineal body. It accounts for 85% of all urethral injuries and is the most vulnerable segment of the anterior urethra. - Sabiston Textbook of Surgery, p. 752
Mechanism of Injury
The classic mechanism is a straddle injury - compression of the bulbar urethra against the inferior border of the pubic symphysis by a fall astride a hard object (bicycle crossbar, fence rail, manhole cover, ship's rigging) or a direct perineal blow (assault, sport). The urethra is crushed between the object and the bony symphysis, causing contusion or frank rupture. - Pye's Surgical Handicraft, p. 314
Clinical Features
| Feature | Details |
|---|---|
| Blood at urethral meatus | Present in 37-93% of cases; the single most important sign |
| Inability to void / urinary retention | Due to disruption of urethral continuity |
| Butterfly perineal hematoma | Pathognomonic sign (see image below) |
| Perineal pain and swelling | From local crush injury |
Butterfly Hematoma - Explained
When Buck's fascia ruptures, blood and urine spread along the fascial planes. Because Colles' fascia (the perineal extension of Scarpa's fascia) is attached at the:
- Posterior: perineal body
- Lateral: pubic rami and fascia lata
...extravasation is confined to form a "butterfly" pattern spanning the scrotum, perineum, and lower abdominal wall, but NOT the thighs or beyond the inguinal ligament.
Investigations
1. Retrograde Urethrogram (RUG) - Gold Standard
- When: Performed whenever blood is at the meatus after perineal/pelvic trauma
- How: Patient placed obliquely; contrast fills the entire urethra under gentle penile stretch; images taken in the oblique position
- Findings: Loss of urethral contour, extravasation of contrast beyond the normal bulbar cone
Critical rule: Do NOT attempt blind urethral catheterization before RUG - this can convert a partial tear into a complete disruption.
Panel A shows the normal anatomy of the bulbar urethra (the "cone" shape); Panel B shows traumatic urethral disruption with contrast extravasation.
Management
Immediate Priority
Bladder drainage is the first urgent step.
Algorithm
Blood at meatus / retention after straddle injury
↓
Retrograde urethrogram (RUG)
↓
┌────────────────────────────────┐
│ Partial tear │ Complete rupture
│ (contrast reaches bladder) │ (no contrast in bladder)
└──────────┬─────────────────────┘
↓ ↓
Single gentle attempt at Suprapubic catheter (SPC)
urethral catheterization (percutaneous or open)
by experienced urologist
with 12Fr soft catheter
↓
Fails → SPC
- Pye's Surgical Handicraft recommends: one expert attempt at 12Fr soft catheter; if fails, immediate suprapubic catheterization. Urethrography at ~14 days, then urethroscopic assessment with placement of a Silastic catheter across the rupture for a further 10-14 days. - p. 314
- Sabiston states: straddle injuries to the bulbar urethra require prompt urinary drainage; most can be repaired primarily, but if extensive local tissue damage exists, suprapubic drainage + delayed repair is preferred. - p. 752
Delayed Repair / Urethroplasty
Once the acute phase is managed, stricture formation is the major long-term concern:
| Stricture Length | Treatment |
|---|---|
| ≤2 cm | Complete excision + end-to-end primary anastomosis (excise 1 cm beyond each end of stricture) |
| >2 cm | Patch graft urethroplasty - midline urethrotomy + buccal mucosa graft (onlay) |
| Very long / dense fibrosis | Distal penile fasciocutaneous flap ± buccal mucosa; success >80% in single-stage |
- Buccal mucosa grafts in the bulbar region should use an onlay technique (dorsal or ventral) to maximize vascularization from the corpus spongiosum. - Smith & Tanagho's General Urology, p. 667
Complications
| Complication | Notes |
|---|---|
| Urethral stricture | Most common late complication; monitor with uroflowmetry, RUG, cystoscopy |
| Erectile dysfunction | Less common than with posterior urethral injuries but occurs |
| Periurethral abscess | Requires drainage + antibiotics |
| Urethrocutaneous fistula | Usually requires surgical repair |
| Urinary incontinence | Uncommon with anterior urethral injuries |
Key Distinctions: Bulbar vs. Posterior Urethral Rupture
| Feature | Bulbar (Anterior) | Posterior (Membranous) |
|---|---|---|
| Mechanism | Straddle/direct perineal blow | Pelvic fracture (RTA, crush, fall from height) |
| Associated injuries | Usually isolated | Pelvic ring fractures (almost invariable) |
| Hematoma | Butterfly perineal hematoma | Pelvic hematoma, bladder displaced cephalad ("pie-in-sky") |
| Incontinence risk | Low | High |
| ED risk | Moderate | High |
| Initial management | SPC or gentle catheterization | SPC (immediate suprapubic cystotomy) |
Sources: Sabiston Textbook of Surgery (11th ed.), p. 752-753 | Pye's Surgical Handicraft, p. 314-315 | Smith & Tanagho's General Urology (19th ed.), p. 667-668
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