A 28-year-old woman is brought to the trauma center 20 minutes after a stab wound to the right lower chest at the 5th intercostal space. She is alert, blood pressure 94/62 mmHg, heart rate 118 bpm, respiratory rate 22/min. Breath sounds are present bilaterally. Abdomen is soft but she complains of right-sided pain. FAST shows no free fluid in the pericardium or peritoneum. Chest X-ray is normal. What is the most appropriate next step?

Explanation

## Clinical Context This patient has a **penetrating thoracoabdominal wound** (5th intercostal space—below the diaphragm, above the costal margin) with: - **Hemodynamic stability** (BP 94/62 is borderline but not shock) - **No peritoneal free fluid** on FAST - **Normal chest X-ray** (no pneumothorax, hemothorax) - **Equivocal abdominal findings** (soft but right-sided pain) The critical question: **Has the peritoneum been violated?** If yes → abdominal exploration. If no → observation. ## Diagnostic Approach for Penetrating Thoracoabdominal Wounds **Key Point:** Wounds between the 4th and 8th intercostal spaces can penetrate the diaphragm and enter the peritoneal cavity. FAST alone is insufficient to exclude peritoneal penetration—you must determine if the fascia/peritoneum is breached. **High-Yield:** In a **hemodynamically stable** patient with a penetrating thoracoabdominal wound and **negative FAST**, the gold standard is **local wound exploration** or **diagnostic laparoscopy** to assess peritoneal violation. **Mnemonic:** **STAB** (Stable Thoracoabdominal wound Assessment): - **S**table vitals → selective non-operative management - **T**horacoabdominal location → risk of diaphragmatic injury - **A**ssess peritoneal violation (exploration/laparoscopy) - **B**ased on findings → observe or operate ## Why Local Wound Exploration or Laparoscopy? 1. **Local wound exploration:** Direct visualization of fascia/peritoneum at the wound site under local anesthesia - If peritoneum intact → safe observation - If peritoneum violated → proceed to laparotomy 2. **Diagnostic laparoscopy:** Allows inspection of diaphragm, viscera, and peritoneal cavity without full laparotomy - Sensitivity ~95% for peritoneal penetration - Therapeutic if minor bleeding or diaphragmatic repair needed **Clinical Pearl:** Hemodynamically stable patients with penetrating thoracoabdominal wounds should NOT undergo routine laparotomy. Selective non-operative management (with serial exams) is safe if peritoneal integrity is confirmed. ## Why Not Observation Alone? FAST is **not 100% sensitive** for detecting small amounts of blood or peritoneal violation. A negative FAST does not exclude diaphragmatic injury or early peritoneal bleeding. You must actively confirm peritoneal integrity. ## Why Not CT? In a penetrating trauma patient, CT is less sensitive than direct visualization for small peritoneal violations and adds time. Laparoscopy/exploration is faster and more definitive. ## Why Not Immediate Laparotomy? The patient is hemodynamically stable and FAST is negative. Routine laparotomy for all penetrating thoracoabdominal wounds increases morbidity (adhesions, infection). Selective approach based on peritoneal violation is standard. [cite:ATLS 10th Edition, Chapter 4: Thoracic Trauma; Trauma Surgery Core Curriculum]