A 32-year-old male arrives at the trauma bay following a motor vehicle collision with severe blunt abdominal trauma. On examination, he is hypotensive (BP 85/55 mmHg), tachycardic (HR 128/min), with a distended, tender abdomen. Two large-bore IV lines are secured and fluid resuscitation initiated. Which investigation is most appropriate to confirm the diagnosis of intra-abdominal hemorrhage and guide immediate management?

Explanation

## Investigation of Choice in Unstable Trauma Patient **High-Yield:** In a hemodynamically unstable patient with suspected intra-abdominal hemorrhage, FAST (Focused Assessment with Sonography for Trauma) is the investigation of choice because it is: - Rapid (completed in < 2–3 minutes) - Non-invasive and repeatable at the bedside - Highly sensitive for detecting free fluid in the peritoneal cavity (pericardial, pleural, and peritoneal spaces) - Does not delay resuscitation or operative intervention **Key Point:** FAST evaluates four key areas: 1. Perihepatic (Morrison's pouch) — most dependent area in supine patient 2. Perisplenic 3. Pelvic 4. Pericardial (for hemopericardium) **Clinical Pearl:** In this case, a positive FAST (free fluid in the abdomen) in a hypotensive patient with blunt trauma is an indication for **immediate exploratory laparotomy** without further imaging. The patient is in hemorrhagic shock (Class III–IV) and does not tolerate the time required for CT scanning. **Mnemonic: FAST** — Focused Assessment with Sonography for Trauma ## Why FAST Over Alternatives | Investigation | Timing | Stability Requirement | Role in Unstable Patient | |---|---|---|---| | FAST | < 3 min | Bedside, any BP | **Gold standard for unstable trauma** | | DPL | 5–10 min | Requires procedure | Invasive; largely replaced by FAST | | CT abdomen | 10–20 min | Requires transport, stable BP | Contraindicated in unstable patient; used in stable cases for grading | | Lactate/base deficit | Variable | Lab processing | Prognostic marker, not diagnostic | **Tip:** Remember the ATLS principle: **Do not delay resuscitation or operative intervention for investigations.** In a shocked trauma patient, FAST + clinical judgment = decision to operate.