A 28-year-old woman is brought to the emergency department following a road traffic accident with signs of hemorrhagic shock (BP 80/50 mmHg, HR 135/min, RR 28/min). After initiating massive transfusion protocol, the trauma team performs a FAST exam which is positive for free fluid in the pelvis. Imaging reveals a complex liver laceration with active bleeding. Which is the most common solid organ injury in blunt abdominal trauma?

## Most Common Solid Organ Injury in Blunt Abdominal Trauma ### Epidemiology **Key Point:** The **spleen** is the most common solid organ injured in blunt abdominal trauma, accounting for approximately 40–55% of all solid organ injuries in this setting. This is a well-established fact cited across major trauma surgery references including ATLS, Sabiston, and Schwartz's Principles of Surgery. ### Frequency of Solid Organ Injuries | Organ | Frequency | Mechanism | Severity Range | |-------|-----------|-----------|----------------| | **Spleen** | **Most common (~40–55%)** | Deceleration, left-sided impact, rib fractures | Grade I–V (AAST scale) | | Liver | Second most common (~35–45%) | Deceleration, direct impact | Grade I–VI | | Kidney | ~10–15% | Blunt flank trauma | Grade I–V | | Pancreas | Rare (~2–3%) | Crush injury, handlebar trauma | Often associated with duodenal injury | **High-Yield:** Although the patient in this vignette has a hepatic laceration (which is the second most common solid organ injury), the question asks for the **most common** solid organ injury in blunt abdominal trauma overall — which is **splenic rupture**. ### Why the Spleen Is Most Commonly Injured 1. **Anatomical vulnerability:** The spleen lies in the left upper quadrant, relatively unprotected, and is susceptible to direct blows and deceleration forces. 2. **Fragile capsule:** The splenic capsule is thin and tears easily with compressive or shearing forces. 3. **Association with rib fractures:** Left lower rib (9th–11th) fractures are a classic marker of splenic injury. 4. **Less mobile:** The spleen is relatively fixed by its ligamentous attachments, making it prone to laceration during deceleration. ### Clinical Pearl **Splenic injury** is the most common cause of preventable death from abdominal trauma. Hemodynamically stable patients with splenic injuries (Grades I–III) are managed **non-operatively** with close monitoring. Hemodynamically unstable patients or those with high-grade injuries (Grade IV–V) may require **angioembolization** or **splenectomy**. **Mnemonic: SPLEEN Injury (High-Yield)** - **S**pleen = #1 solid organ injured in blunt trauma - **P**eritoneal signs → operative management - **L**eft lower rib fractures → suspect splenic injury - **E**mbolization for Grade III–IV in stable patients - **E**xpectant (non-operative) for Grade I–II - **N**on-operative management success rate ~80–90% ### Management Algorithm ``` Blunt splenic injury on imaging ↓ Hemodynamically stable? Yes → Non-operative management (ICU monitoring, serial Hb, imaging) No → Damage control laparotomy / splenectomy ``` [cite: ATLS 10th Edition, Chapter 5; Sabiston Textbook of Surgery, 20th Edition, Chapter 17; Schwartz's Principles of Surgery, 11th Edition]