American Association for the Surgery of Trauma
Select Highest Injury Present
Assessment Pending
Select the highest radiologic (RUG) or clinical finding to determine the AAST Urethral Injury Grade.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
When to Suspect Urethral Injury — Classic Triad (Pelvic Fracture + Blood + High-Riding Prostate)
Blood at the urethral meatus (present in 75–90% of anterior and posterior urethral injuries) — most sensitive sign
Pelvic fracture (especially bilateral pubic rami fractures, Malgaigne fracture, or symphysis diastasis > 2.5 cm) — 5–15% of pelvic fractures have associated urethral injury
Inability to void or palpable distended bladder with suprapubic tenderness
"High-riding prostate" on digital rectal exam (DRE) — prostate displaced superiorly and posteriorly due to disruption of puboprostatic ligaments (specific but not sensitive; only 20–40% of posterior urethral injuries have palpable finding)
Scrotal or perineal hematoma ("butterfly" or "saddle" sign extending to proximal thighs) — suggests extravasation into urogenital diaphragm
Gross hematuria with known pelvic fracture or straddle injury (penetrating or blunt)
Penetrating trauma to perineum, penis, or lower abdominal gunshot wound (bullet trajectory crossing midline or below pubic symphysis)
Iatrogenic injury during urethral catheterization (resistance followed by bleeding, inability to advance, or false passage)
Post-void imaging showing contrast extravasation (retrograde urethrogram performed for other indication)
Anatomic Classification — Posterior vs Anterior Urethra (Crucial for Management)
| Urethral Segment | Anatomic Boundaries | Typical Mechanism | Prognosis | Associated Injuries |
|---|---|---|---|---|
| Posterior urethra (prostatomembranous) | Prostatic urethra (within prostate) + membranous urethra (through urogenital diaphragm, 1.5–2 cm length). Most vulnerable segment due to fixation by puboprostatic ligaments. | Pelvic fracture (shearing at puboprostatic ligament attachment on prostate) — 90% of posterior injuries. Falls from height, motor vehicle collision, crush injury. | Fair to good. 60–80% successful delayed urethroplasty; early realignment preserves potency in 30–50%; incontinence in 20–40%. | Bladder neck injury (15–30%), rectal injury (10–20%), major pelvic vascular injury (iliac vein/artery 5–10%), erectile nerves (cavernous nerves run posterolateral to prostate — damage causes impotence in 40–70%) |
| Anterior urethra (bulbous + penile) | Bulbar urethra (from urogenital diaphragm to penoscrotal junction, most common anterior injury site) + penile urethra (within corpus spongiosum from penoscrotal to meatus). | Straddle injury (fall astride object — bicycle crossbar, fence, beam) compressing bulbous urethra against pubic symphysis — 75% of anterior injuries. Penile fracture (tunica albuginea tear with urethral injury in 10–30%). Penetrating trauma, iatrogenic (TURP, cystoscopy, catheterization). | Good to excellent. Urethroplasty success rate 85–95% for bulbar injuries. Endoscopic realignment for short bulbous strictures 50–80% success. | Corpus spongiosum injury (bleeding, hematoma), cavernosal injury (penile fracture, impotence if bilateral injury), scrotal hematoma, testicular rupture (concomitant in 5–10%) |
Mechanism-Specific Injury Patterns
Pelvic fracture posterior urethral injury occurs via shearing of the membranous urethra at the urogenital diaphragm while the prostate is displaced posteriorly and superiorly (""posterior prostate dislocation""). The puboprostatic ligaments tear, detaching the prostate from the pubic symphysis. This creates a distracting gap of 0.5–5 cm between the torn ends of the urethra. The bladder neck may be injured in 15–30% (Grade V AAST bladder injury). Straddle injury (anterior bulbous urethra) compresses the urethra against the inferior pubic ramus, causing contusion (Grade I), partial tear (Grade II–III), or complete rupture (Grade IV–V). Penile fracture urethral injury occurs from rotational or bending force while erect; the tunica albuginea tears, and the urethra is sheared within the corpus spongiosum. Iatrogenic injuries (most common in elderly men with large prostates during Foley placement) often cause false passages in the bulbous or prostatic urethra, which may heal with catheter drainage or require endoscopic realignment.
Related Scores in Practice
In clinical practice, this assessment is frequently evaluated alongside other validated measures. Depending on the patient's presentation and specific diagnostic requirements, you may also need to utilize the Aast Bladder Injury Scale or the Aast Renal Injury Scale to formulate a comprehensive care plan.
Last Comprehensive Review: 2026