Emergency Medicine · Year 3 · from Emergency Medicine

Case 1: FAST Exam - The Hypotensive Trauma Patient

Patient Demographics

  • Age: 28 years
  • Sex: Male
  • Occupation: Construction worker

Chief Complaint

"Car accident - he's really hurt."

History of Present Illness

A 28-year-old male is brought by EMS after high-speed motor vehicle collision. He was the unrestrained driver when his vehicle struck a tree at approximately 50 mph. Airbags deployed. He was initially alert at scene but has become increasingly confused en route. EMS reports significant steering wheel deformity and dashboard intrusion.

Initial Assessment (Trauma Activation)

ESI Level: 1 - Major trauma, hemodynamic instability

First Impression:

  • Appearance: Pale, diaphoretic, confused
  • Work of breathing: Tachypneic, clear bilateral breath sounds
  • Circulation: Pale, tachycardic, delayed cap refill

Vital Signs:

  • Heart rate: 132 bpm
  • Blood pressure: 82/54 mmHg
  • Respiratory rate: 28 breaths/min
  • SpO2: 96% on NRB
  • Temperature: 36.4C
  • GCS: 12 (E3V4M5)

Trauma Primary Survey

A - Airway: Patent, speaking in words B - Breathing: Bilateral breath sounds, tachypneic C - Circulation: Hypotensive, tachycardic, pale - SHOCK D - Disability: GCS 12, moving all extremities, pupils equal E - Exposure: Seatbelt sign across abdomen, no obvious external hemorrhage

FAST Exam Indication

Hypotensive trauma patient - need to identify source of bleeding

FAST = Focused Assessment with Sonography in Trauma

Goal: Identify free fluid (blood) in:

  1. Perihepatic space (Morison's pouch)
  2. Perisplenic space
  3. Pelvis
  4. Pericardium

FAST Exam Protocol

Equipment:

  • Portable ultrasound machine
  • Curvilinear (abdominal) probe (2-5 MHz)
  • Phased array probe for cardiac view (optional)

Patient Position: Supine (trauma bay)

Four Views of FAST:

1. Right Upper Quadrant (RUQ) - Morison's Pouch:

  • Probe: Curvilinear, 9-11 o'clock position
  • Location: Right anterior axillary line, 9th-11th intercostal space
  • Target: Hepatorenal space (most dependent space in supine patient)
  • FINDING: POSITIVE - Anechoic stripe (black) between liver and kidney

2. Left Upper Quadrant (LUQ) - Splenorenal Space:

  • Probe: More posterior than RUQ (spleen is more posterior)
  • Location: Left posterior axillary line, 6th-9th intercostal space
  • Target: Perisplenic space, splenorenal recess
  • FINDING: POSITIVE - Fluid around spleen and above diaphragm

3. Pelvis (Suprapubic):

  • Probe: Midline suprapubic, transverse and sagittal
  • Target: Rectovesical pouch (males), pouch of Douglas (females)
  • FINDING: POSITIVE - Fluid posterior to bladder

4. Cardiac (Subxiphoid):

  • Probe: Subxiphoid, angled toward left shoulder
  • Target: Pericardial effusion
  • FINDING: NEGATIVE - No pericardial fluid

FAST Results Summary

ViewFinding
RUQ (Morison's)POSITIVE - free fluid
LUQ (Splenorenal)POSITIVE - free fluid
PelvisPOSITIVE - free fluid
CardiacNEGATIVE

INTERPRETATION: Significant hemoperitoneum - patient needs emergent laparotomy

Clinical Decision-Making

Hypotensive trauma + Positive FAST = OR for laparotomy

NO CT SCAN - Patient too unstable; would delay definitive treatment

Algorithm:

Blunt Trauma + Hypotension
         ↓
    FAST Exam
         ↓
    POSITIVE → Operating Room (exploratory laparotomy)
         ↓
    NEGATIVE → Consider other sources (chest, pelvis, external)
                Consider repeat FAST or CT if stable

Resuscitation While Preparing for OR

Massive Transfusion Protocol Activated:

  • 4 units PRBC
  • 2 units FFP
  • 1 unit platelets
  • TXA 1g IV (within 3 hours of injury)

Access:

  • Two large-bore IVs (18g or larger)
  • IO backup available

Blood Pressure Response:

  • After 2 units PRBC: BP 94/62 (transient response = ongoing hemorrhage)

Operative Findings

Exploratory Laparotomy:

  • 2.5L hemoperitoneum
  • Grade III splenic laceration with active hemorrhage
  • Splenectomy performed
  • Small mesenteric tear - repaired
  • No other injuries

Post-Operative Course

  • ICU admission
  • Additional transfusion: 2 units PRBC
  • Hemodynamically stable post-op
  • Transferred to floor day 2
  • Vaccinations for asplenia (pneumococcal, meningococcal, H. flu)
  • Discharged day 5

Teaching Points

  1. FAST is a focused exam: Detects FREE FLUID, not organ injury
  2. Positive FAST + hypotension = OR: No CT needed; delays definitive care
  3. Negative FAST doesn't rule out injury: Sensitivity ~80-90%; repeat if clinical concern
  4. Morison's pouch most sensitive: Most dependent space in supine patient
  5. Look at diaphragm: Fluid above diaphragm suggests hemothorax (eFAST)
  6. Probe positioning matters: LUQ more posterior than RUQ
  7. FAST takes <5 minutes: Should be part of primary survey
  8. Serial exams valuable: If initially negative, may turn positive as bleeding continues

Clinical Image

Image Description: Ultrasound image of the right upper quadrant demonstrating a positive FAST exam with an anechoic (black) stripe of free fluid in Morison's pouch between the liver (above) and kidney (below), indicating hemoperitoneum.

Attribution: Image from Wikimedia Commons, FAST exam positive. Licensed under CC BY-SA 4.0. Source: https://commons.wikimedia.org/wiki/File:FAST-Exam-Positive.jpg

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