A 32-year-old man is brought to the emergency department following a motor vehicle collision with severe blunt abdominal trauma. On examination, he is hypotensive (BP 90/60 mmHg), tachycardic (HR 128/min), and has a distended abdomen with severe tenderness. Two large-bore IV lines are established and fluid resuscitation initiated. Which investigation is most appropriate to confirm the diagnosis of intra-abdominal hemorrhage and guide immediate surgical intervention?
A. Serial abdominal examination and laboratory markers (lactate, base deficit)
B. Focused Assessment with Sonography for Trauma (FAST)
C. Computed tomography of abdomen and pelvis with IV contrast
D. Diagnostic peritoneal lavage (DPL)
Explanation
Investigation of Choice in Hemorrhagic Shock from Blunt Abdominal Trauma
Key Point
FAST (Focused Assessment with Sonography for Trauma) is the gold standard first-line imaging modality in hemodynamically unstable trauma patients with suspected intra-abdominal hemorrhage.
Why FAST is Optimal
1.
Speed and Accessibility
Performed at bedside in <2 minutes
No patient transport required
Can be repeated serially during resuscitation
Operator-dependent but highly sensitive in experienced hands
2.
Hemodynamic Stability Irrelevant
Works in hypotensive patients (unlike CT)
Detects free fluid in peritoneal cavity
Guides decision for immediate surgical exploration
3.
Sensitivity in Trauma
Detects as little as 250 mL free fluid
Sensitivity ~95% for hemoperitoneum in blunt trauma
Specificity ~96% for detecting free fluid
FAST Protocol — Four Views
Table
View
Anatomical Target
Significance
Perihepatic (Morrison's pouch)
Right upper quadrant
Most dependent area; detects ~250 mL
Perisplenic
Left upper quadrant
Splenic injuries; detects ~250 mL
Pelvic
Suprapubic region
Pelvic fractures, bladder injuries
Pericardial
Subxiphoid view
Cardiac tamponade, hemopericardium
Clinical Pearl
A positive FAST in a hemodynamically unstable patient with blunt abdominal trauma is an indication for immediate laparotomy — no further imaging needed.
High-YieldNEET PG
FAST + hypotension + blunt trauma = go to OR. Do not delay for CT.
Why Other Options Are Suboptimal
Diagnostic Peritoneal Lavage (DPL):
Invasive procedure requiring local anesthesia and small incision
Takes 5–10 minutes; slower than FAST
Largely replaced by FAST in modern trauma centers
Cannot be repeated as easily
Positive in this case but not first-line
CT Abdomen/Pelvis with IV Contrast:
Requires hemodynamic stability and transport
Contraindicated in this hypotensive patient (SBP 90 mmHg)
Takes 15–30 minutes; patient may decompensate
Appropriate for stable patients with blunt trauma to grade injuries
Not suitable for immediate decision-making in hemorrhagic shock
Serial Abdominal Exam + Lactate/Base Deficit:
Useful for ongoing monitoring and resuscitation endpoints
Does NOT confirm diagnosis of intra-abdominal hemorrhage
Lactate and base deficit are markers of tissue hypoperfusion, not specific for source
Should accompany imaging, not replace it
Mnemonic
FAST = Focused Assessment with Sonography for Trauma
Focused → bedside, rapid
Assessment → detects free fluid
Sonography → ultrasound, no radiation
Trauma → gold standard in unstable patients
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