Focused Assessment with Sonography in Trauma (FAST)

Focused Assessment with Sonography in Trauma (FAST)

Focused Assessment with Sonography in Trauma (FAST)

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FAST Fundamentals - Trauma's First Look

  • Goal: Rapid bedside ultrasound to detect free fluid (hemoperitoneum, hemopericardium) in hypotensive trauma patients.
  • Core Views (4 Ps):
    • Pericardial (subxiphoid)
    • Perihepatic (Morison's Pouch)
    • Perisplenic
    • Pelvic (suprapubic)
  • eFAST adds bilateral anterior thoracic views to screen for pneumothorax.

eFAST scan windows on a torso

⭐ FAST is highly specific for intraperitoneal fluid but can miss bowel/mesenteric injuries and retroperitoneal bleeds.

The 4 Views - A Quick Tour

A standardized sequence to rapidly identify hemoperitoneum or pericardial effusion.

  • 1. RUQ (Hepatorenal / Morison's Pouch):

    • Probe at right mid-axillary line (8th-11th intercostal space).
    • Visualizes potential space between liver and right kidney.

    ⭐ Most sensitive view for intraperitoneal free fluid in a supine patient.

  • 2. Subxiphoid (Pericardial):

    • Probe inferior to xiphoid, aimed at the left shoulder.
    • Crucial for identifying pericardial effusion/tamponade.
  • 3. LUQ (Splenorenal):

    • Probe at left posterior-axillary line (6th-9th intercostal space).
    • Examines the space between the spleen and left kidney.
  • 4. Suprapubic (Pelvic):

    • Probe superior to pubic symphysis (transverse & sagittal planes).
    • Visualizes rectovesical pouch (males) or Pouch of Douglas (females).

FAST exam probe positions and corresponding sonoanatomy

Interpreting Findings - Fluid, Air, & Action

FAST exam: Free fluid in Morison's pouch

  • Fluid (Blood): Appears anechoic (black). Accumulates in dependent areas.
    • Key sites: Perihepatic (Morison's pouch), perisplenic, pelvic (Pouch of Douglas), pericardial.
  • Pneumothorax (eFAST):
    • Present: Normal "lung sliding" (shimmering pleura) & "comet tail" artifacts.
    • Absent: No lung sliding; "stratosphere" or "barcode" sign on M-mode.

⭐ In a hemodynamically stable patient, a positive FAST doesn't automatically mean surgery. A follow-up CT scan is crucial to quantify the volume of hemoperitoneum and grade the solid organ injury, guiding potential non-operative management.

Clinical Algorithm - The Decision Tree

⭐ A key limitation: FAST does not reliably visualize retroperitoneal, diaphragmatic, or bowel injuries. A negative FAST in a stable patient with a high-risk mechanism or persistent abdominal pain still warrants a CT scan.

  • The FAST exam is a rapid bedside ultrasound to detect hemoperitoneum or pericardial effusion in trauma.
  • It assesses four key windows: hepatorenal (Morison's pouch), splenorenal, subxiphoid (pericardial), and suprapubic (pelvic).
  • A positive FAST in an unstable patient is an indication for an immediate exploratory laparotomy.
  • Key limitation: It has poor sensitivity for retroperitoneal, solid organ, or diaphragmatic injuries.
  • For stable patients, a CT scan is the gold standard, especially if the FAST is equivocal or negative with high suspicion.
  • The eFAST adds bilateral thoracic views to detect pneumothorax or hemothorax.

Practice Questions: Focused Assessment with Sonography in Trauma (FAST)

Test your understanding with these related questions

A 56-year-old man is brought to the emergency department 25 minutes after he was involved in a high-speed motor vehicle collision where he was the unrestrained passenger. He has severe lower abdominal and pelvic pain. On arrival, he is alert and oriented. His pulse is 95/min, respirations are 22/min, and blood pressure is 106/62 mm Hg. Examination shows severe tenderness to palpation over the lower abdomen and over the left anterior superior iliac spine. There is no limb length discrepancy. Application of downward pressure over the pelvis shows no springy resistance or instability. Rectal examination is unremarkable. A focused assessment with sonography shows no free fluid in the abdomen. There is no blood at the urethral meatus. Placement of a Foley catheter shows gross hematuria. An x-ray of the pelvis shows a fracture of the left pelvic edge. Which of the following is the most appropriate next step in management?

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Flashcards: Focused Assessment with Sonography in Trauma (FAST)

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Traumatic aortic rupture (due to trauma and/or deceleration injury) most commonly occurs at the _____

TAP TO REVEAL ANSWER

Traumatic aortic rupture (due to trauma and/or deceleration injury) most commonly occurs at the _____

aortic isthmus

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