A 28-year-old woman sustains blunt abdominal trauma from a fall and is haemodynamically unstable despite two units of packed red blood cells. On FAST examination, free fluid is detected in multiple quadrants. Which is the most common anatomical site of solid organ injury requiring laparotomy in unstable blunt abdominal trauma?

## Most Common Solid Organ Injury Requiring Laparotomy in Unstable Blunt Abdominal Trauma **Key Point:** The **spleen** is both the most commonly injured solid organ in blunt abdominal trauma overall AND the most common solid organ requiring laparotomy in haemodynamically unstable patients. Grade IV–V splenic injuries are the leading operative indication in this setting. ### Why the Spleen Dominates 1. **Most frequently injured organ:** The spleen's anatomical position (unprotected by the rib cage inferiorly, fixed at the splenic hilum) makes it the most vulnerable solid organ in blunt trauma — accounting for approximately **40–50% of all solid organ injuries** (ATLS 10th Edition). 2. **Grade IV–V injuries mandate surgery:** High-grade splenic injuries (Grade IV: involving segmental or hilar vessels with >25% devascularization; Grade V: completely shattered or devascularized spleen) produce massive haemorrhage and are the most common reason for emergent laparotomy in unstable blunt trauma. 3. **Non-operative management (NOM) failure:** While NOM is attempted in stable patients, haemodynamic instability with Grade IV–V splenic injury is a direct operative indication. Splenectomy or splenorrhaphy is performed urgently. 4. **Liver injuries — important but less common as operative indication:** Hepatic lacerations are the second most common solid organ injury and can also require laparotomy, but the spleen remains the #1 operative solid organ in unstable blunt trauma per ATLS and Sabiston. ### AAST Organ Injury Scale — Spleen | Grade | Description | Management | |-------|-------------|------------| | I–II | Subcapsular haematoma / laceration <3 cm | Conservative | | III | Laceration >3 cm, not involving hilar vessels | Conservative (if stable) | | **IV** | **Hilar vascular injury, >25% devascularization** | **Operative** | | **V** | **Shattered spleen / complete devascularization** | **Operative (splenectomy)** | ### Why the Other Options Are Incorrect - **Option B (Hepatic laceration):** Liver is the second most commonly injured organ and second most common operative indication — not the first. High-grade hepatic injuries do require laparotomy but are less frequent than splenic injuries overall. - **Option A (Renal pedicle avulsion):** Rare injury; kidneys are retroperitoneal and relatively protected. Renal injuries are managed non-operatively in the vast majority of cases. - **Option D (Pancreatic transection):** Uncommon injury requiring high-energy deceleration; not a leading cause of haemodynamic instability requiring emergent laparotomy. **High-Yield:** Spleen = most commonly injured solid organ in blunt trauma = most common solid organ requiring laparotomy in unstable patients. The liver is a close second and an important distractor. **Clinical Pearl:** In the ATLS algorithm, a haemodynamically unstable patient with free fluid on FAST proceeds directly to laparotomy. The spleen (Grade IV–V rupture) is the most common intraoperative finding. [cite: ATLS 10th Edition; Sabiston Textbook of Surgery, 20th Edition; Schwartz's Principles of Surgery]