A 32-year-old man is brought to the emergency department following a high-speed motor vehicle collision. On primary survey, he is conscious, breathing spontaneously at 24/min, with a blood pressure of 95/62 mmHg and heart rate of 118/min. Breath sounds are present bilaterally. After securing the airway and establishing two large-bore IVs, you proceed to the secondary survey. On abdominal examination, there is severe tenderness in the left upper quadrant with guarding and rigidity. The pelvis is stable on compression. What is the most appropriate next step in management?

## Clinical Context This patient presents with haemodynamic instability (BP 95/62, HR 118) and peritoneal signs (guarding, rigidity) in the left upper quadrant, consistent with splenic injury with active bleeding and peritonitis. ## Primary Survey Status **Key Point:** The patient has already completed the primary survey (A-B-C-D-E intact). The next phase is the secondary survey, which this case represents. ## Secondary Survey Findings - **Left upper quadrant tenderness + guarding + rigidity** → peritoneal irritation/haemorrhage - **Haemodynamic instability** (SBP < 100 mmHg, tachycardia) → active bleeding - **Stable pelvis** → excludes pelvic fracture as bleeding source ## Management Algorithm for Unstable Trauma Patient ```mermaid flowchart TD A[Haemodynamically unstable trauma patient]:::outcome --> B{Peritoneal signs present?}:::decision B -->|Yes| C[Perform FAST exam]:::action C --> D{Free fluid in abdomen?}:::decision D -->|Yes| E[Emergency laparotomy]:::urgent D -->|No| F[Reassess, consider other bleeding source]:::action B -->|No| G[CT imaging if stable]:::action ``` ## Why FAST is the Answer **High-Yield:** FAST (Focused Assessment with Sonography for Trauma) is the **gold standard screening tool** for free intra-abdominal fluid in unstable trauma patients because: 1. **Performed at bedside** — no transport delay 2. **Rapid** — completed in < 2 minutes 3. **Sensitive for haemoperitoneum** — detects as little as 250 mL fluid 4. **Guides immediate intervention** — positive FAST + haemodynamic instability = straight to OR **Clinical Pearl:** In an unstable patient with peritoneal signs, you do NOT wait for CT imaging. FAST + clinical judgment suffices for operative decision-making. ## FAST Examination Technique - **Four views:** Perihepatic (Morrison's pouch), perisplenic, pelvic, pericardial - **Positive finding:** Anechoic (black) fluid in dependent areas - **Sensitivity in trauma:** 90–95% for significant haemoperitoneum ## Why NOT CT Scan? **Warning:** CT requires patient transport out of the resuscitation bay, delays definitive treatment, and is contraindicated in haemodynamically unstable patients. Reserve CT for stable patients or those with equivocal FAST findings.