A 28-year-old woman is brought to the trauma centre following a stab wound to the right upper quadrant. She is haemodynamically stable with mild right upper quadrant tenderness. FAST examination shows no free fluid. Which investigation is most appropriate as the next step to exclude hepatic injury?

## Investigation of Choice for Penetrating Hepatic Injury **Key Point:** Contrast-enhanced CT (CECT) abdomen and pelvis is the investigation of choice for haemodynamically stable patients with penetrating abdominal trauma and negative FAST. ### Rationale for CECT **High-Yield:** CECT is preferred because it: - Detects parenchymal lacerations, haematomas, and active bleeding (arterial blush) - Grades liver injury (AAST scale I–V) - Identifies associated injuries (splenic, renal, pancreatic, hollow viscus) - Guides conservative vs. operative management - Sensitivity >95% for clinically significant hepatic injury ### Clinical Context: Penetrating vs. Blunt Trauma **Clinical Pearl:** In **blunt hepatic trauma**, stable patients with negative FAST may be observed. However, in **penetrating trauma** (stab/gunshot), the trajectory is unpredictable. Even if FAST is negative, CT is mandatory to exclude occult parenchymal injury, bile duct injury, or hepatic vein injury that may declare itself later. ### Management Algorithm ```mermaid flowchart TD A[Penetrating RUQ trauma]:::outcome --> B{Haemodynamically stable?}:::decision B -->|No| C[Resuscitate + Exploratory laparotomy]:::urgent B -->|Yes| D[FAST examination]:::action D --> E{Free fluid?}:::decision E -->|Yes| F[Exploratory laparotomy]:::action E -->|No| G[CECT abdomen/pelvis]:::action G --> H{Injury detected?}:::decision H -->|Grade I–II, stable| I[Conservative management + ICU monitoring]:::outcome H -->|Grade III–V or active bleed| J[Exploratory laparotomy]:::action H -->|No injury| K[Observe, serial exams]:::outcome ``` ### Comparison of Investigations | Investigation | Sensitivity | Specificity | Role in Penetrating Trauma | |---|---|---|---| | **CECT** | >95% | Excellent | Gold standard for stable patients | | **Diagnostic laparoscopy** | 95–98% | Excellent | Reserved for equivocal cases or peritoneal penetration assessment | | **Hepatic ultrasound** | 70–80% | Moderate | Limited; operator-dependent, poor for grading | | **Serial exam + repeat FAST** | Variable | Low | Insufficient for penetrating trauma; high miss rate | **Mnemonic:** **CECT for Penetrating Trauma = SAFE** (Sensitivity, Associated injuries, Grading, Excludes occult injury) ### Why Serial Observation Alone Is Inadequate **Warning:** Penetrating trauma has unpredictable trajectories. A negative FAST does NOT exclude hepatic injury (e.g., small laceration without haemoperitoneum, bile duct injury, hepatic vein thrombosis). Relying on serial exams risks delayed diagnosis of evolving injury. [cite:ATLS 10th Edition, Chapter 8; Trauma Surgery Textbook]