Abdominal Trauma Imaging

Abdominal Trauma Imaging: Initial Scan - FAST & Furious

• FAST: Focused Assessment with Sonography for Trauma.
• Rapid, portable, non-invasive bedside ultrasound. Detects free intraperitoneal fluid (hemoperitoneum) & pericardial effusion.
• Key role: Rapid triage of hemodynamically unstable patients to OR vs. further imaging.
• Key Views:
  • Perihepatic (Morison's Pouch)
  • Perisplenic
  • Pelvic (Pouch of Douglas/Rectovesical)
  • Pericardial (Subxiphoid)
• eFAST (Extended FAST): Adds bilateral anterior thoracic views to detect pneumothorax or hemothorax.
• Limitations: Operator-dependent; misses retroperitoneal, bowel, contained organ injury.

⭐ > In unstable trauma patients, a positive FAST (free fluid) often indicates need for immediate surgical intervention (laparotomy).

Abdominal Trauma Imaging: CT Scanorama - Protocol Power

CT is key for stable abdominal trauma. Multiphase acquisition is standard.

• CT Protocols:
  • Non-Contrast (NCCT): Baseline for hemorrhage, calcifications.
  • Arterial Phase (AP; 20-35s): Detects active bleeding, pseudoaneurysms, vascular injury.
  • Portal Venous Phase (PVP; 60-90s): Workhorse for solid organ (liver, spleen, kidney), bowel, mesenteric injury.
  • Delayed Phase (DP; 5-15 min): For urinary tract (collecting system, ureter, bladder) injury.

• Interpretation: Systematic approach. Identify lacerations, hematomas, active extravasation, free fluid/air.

⭐ The Portal Venous Phase is the most crucial single phase for evaluating solid organ and bowel injuries in trauma CT.

Abdominal Trauma Imaging: Solid Hits - Organ Grading Game

• CECT Gold Standard: AAST organ injury scales (Grades I-V/VI) guide management.
• Spleen (Most Common):
  • Grade I: Hematoma <10% surface area (SA) / Laceration (Lac) <1cm depth.
  • Grade II: Hematoma 10-50% SA / Intraparenchymal <5cm / Lac 1-3cm.
  • Grade III: Hematoma >50% SA / Ruptured or expanding / Intraparenchymal >5cm / Lac >3cm.
  • Grade IV: Laceration involving segmental/hilar vessels; Major devascularization (>25%).
  • Grade V: Shattered spleen; Hilar vascular injury (devascularized spleen).
• Liver:
  • Grade I: Hematoma <10% SA / Lac <1cm.
  • Grade II: Hematoma 10-50% SA / Intraparenchymal <10cm / Lac 1-3cm.
  • Grade III: Hematoma >50% SA / Ruptured or expanding / Intraparenchymal >10cm / Lac >3cm.
  • Grade IV: Parenchymal disruption 25-75% of a lobe or 1-3 Couinaud segments.
  • Grade V: Parenchymal disruption >75% of a lobe / Juxtahepatic venous injuries (retrohepatic IVC/major hepatic veins).
  • Grade VI: Hepatic avulsion.
• Kidney:
  • Grade I: Contusion / Subcapsular hematoma, non-expanding.
  • Grade II: Laceration <1cm cortex; Non-expanding perirenal hematoma.
  • Grade III: Laceration >1cm cortex (no collecting system rupture).
  • Grade IV: Laceration into collecting system / Main renal artery/vein injury with contained hemorrhage.
  • Grade V: Shattered kidney; Renal pedicle avulsion / Devascularized kidney.

⭐ Active contrast extravasation ("blush") on CECT is a critical sign of ongoing hemorrhage, often warranting urgent intervention (embolization or surgery).

Abdominal Trauma Imaging: Guts & Gore - Viscus & Vascular Villains

• Hollow Viscus Injury (HVI):
  • CT is primary imaging; oral contrast may aid.
  • Key signs:
    • Pneumoperitoneum (free air).
    • Bowel wall thickening (>3-4 mm), abnormal enhancement.
    • Mesenteric infiltration, hematoma, or interloop fluid.
    • Extraluminal oral contrast.
  • Delayed CT scans if initial findings equivocal but suspicion high.
  • Common sites: Jejunum, ileum (near points of fixation).
• Vascular Injury:
  • MDCT Angiography (CTA) is gold standard.
  • Direct signs:
    • Active contrast extravasation ("arterial blush").
    • Pseudoaneurysm, intimal flap, dissection.
    • Vessel occlusion/transection.
  • Indirect signs: Hematoma (retroperitoneal, mesenteric), "sentinel clot" sign.

⭐ Isolated free fluid in blunt abdominal trauma, without solid organ injury, is highly suspicious for hollow viscus or mesenteric injury until proven otherwise.

High‑Yield Points - ⚡ Biggest Takeaways

• FAST scan: Initial for unstable patients, detects free fluid.
• CT with IV contrast: Gold standard for stable patients.
• Solid organ injury grading (liver, spleen, kidney) guides management.
• Active contrast extravasation on CT indicates ongoing bleeding, needs intervention.
• Bowel/mesenteric injury: Look for free air, wall thickening, mesenteric stranding.
• Diaphragmatic rupture: More common on left; "collar sign", organ herniation.
• Retroperitoneal hematoma zones (I, II, III) direct surgical approach.