American Association for the Surgery of Trauma (2018 Revision)
Select Highest Injury Present
Assessment Pending
Select the highest radiologic or operative finding to determine the AAST Renal Injury Grade.
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
When to Suspect Bladder Injury — Clinical Triggers
Gross hematuria after blunt abdominal or pelvic trauma (present in 90–95% of bladder ruptures)
Pelvic fracture (especially pubic rami or symphysis diastasis) — 5–10% of pelvic fractures have associated bladder injury; 89% of extraperitoneal ruptures occur with pelvic fractures
Inability to void or low-volume void with persistent hematuria after catheter placement
Suprapubic pain, tenderness, or abdominal distension with signs of peritonitis (intraperitoneal rupture)
Penetrating trauma to lower abdomen, pelvis, or perineum (gunshot wounds, stab wounds, iatrogenic during pelvic surgery or TURBT)
Blunt trauma with severe deceleration (motor vehicle collision, fall from height, crush injury) with distended bladder at impact
Elevated serum creatinine or BUN without renal injury (urinary ascites from intraperitoneal rupture causes reabsorption of urine)
Mechanisms of Injury — Pathophysiology-Based Classification
| Mechanism | Frequency | Bladder Volume at Impact | Typical Rupture Type | Associated Injuries |
|---|---|---|---|---|
| Blunt trauma (distended bladder) | 60–70% of all bladder ruptures | > 300 mL (full bladder) — hydrostatic pressure ↑ 10× vs empty | Intraperitoneal (80% of distended injuries) — dome rupture | Pelvic fracture in 30% of intraperitoneal ruptures |
| Blunt trauma (empty bladder) | 15–20% | < 100 mL | Extraperitoneal almost exclusively | Pelvic fracture in 95% — shearing forces at pubic rami |
| Pelvic fracture alone | Directly responsible for 85% of extraperitoneal ruptures | Variable, usually empty | Extraperitoneal — bone fragment laceration or ligamentous avulsion | Urethral injury (10–15%), vaginal injury (5–10%) |
| Penetrating trauma | 15–20% | Variable | Mixed (intraperitoneal + extraperitoneal in 40%) | Bowel (50%), iliac vessel (20%), ureter (15%) |
| Iatrogenic | 5–10% (rising) | Variable | Extraperitoneal (most TURBT, TVT sling), intraperitoneal (laparoscopic port placement) | Previous pelvic surgery, radiation cystitis, pelvic anatomy distortion |
Epidemiology and Demographics
Bladder injuries occur in 1.6 per 100,000 population annually in the US. Male-to-female ratio 3:1 (males have higher rates of blunt trauma; females have higher rates of iatrogenic injury from pelvic surgery). Mean age 34 years (range 16–65). Mortality from isolated bladder injury is < 5%, but associated injuries determine overall mortality: pelvic fracture (15% mortality if unstable), major vascular injury (40% mortality), concomitant urethral injury (20% mortality). Intraperitoneal rupture has higher morbidity (peritonitis, sepsis, metabolic derangements from urinary ascites) but lower mortality than extraperitoneal rupture when diagnosed promptly. Delayed diagnosis (> 24 hours) increases mortality from 5% to 25% due to sepsis and multi-organ failure.
Indications for Diagnostic Imaging
Any blunt trauma patient with gross hematuria AND shock (SBP < 90 mmHg) — requires CT cystogram regardless of pelvic fracture presence
Any blunt trauma patient with gross hematuria AND pelvic fracture — requires CT cystogram
Any blunt trauma patient with microscopic hematuria (≥ 3 RBC/HPF) AND high-risk mechanism (deceleration, fall > 10 ft, pelvic fracture) — consider CT cystogram based on clinical judgment
Penetrating trauma to lower abdomen, pelvis, or buttocks — requires CT cystogram or retrograde cystogram
Iatrogenic injury suspected after pelvic surgery, TURBT, or urinary catheter placement — retrograde cystogram is diagnostic
Do NOT rely on standard CT urogram with delayed images alone — 40% of bladder ruptures missed without adequate bladder distension (see imaging section below).
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 Renal Injury Scale, Aast Urethral Injury Scale, Fourniers Gangrene Severity Index, Pelvic Fracture Classification, or the Retrograde Cystogram Protocol to formulate a comprehensive care plan.
Last Comprehensive Review: 2026