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?

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 | 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-Yield:** 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** - **F**ocused → bedside, rapid - **A**ssessment → detects free fluid - **S**onography → ultrasound, no radiation - **T**rauma → gold standard in unstable patients