A 35-year-old woman is brought to the emergency department 4 hours after an assault with a blunt object. She has a large contusion over the left flank with ecchymosis, but no abdominal distension, tenderness, or peritoneal signs. Vital signs are stable (BP 128/82, HR 88, RR 16). Urine dipstick shows no blood. What is the most appropriate next step in management?

Explanation

## Management of Blunt Abdominal/Flank Trauma — Role of CT Imaging **Key Point:** In a hemodynamically stable patient with significant blunt flank trauma, **immediate CT abdomen/pelvis with contrast** is the standard of care to rule out solid organ injury (particularly renal, splenic, or hepatic injury), even in the absence of hematuria or peritoneal signs. ### Why Immediate CT is Indicated Here | Feature | This Patient | Implication | |---------|-------------|-------------| | Mechanism | Blunt assault, flank | High-energy mechanism; retroperitoneal organs at risk | | Contusion size | Large, with ecchymosis | Significant force transmitted | | Hemodynamics | Stable | Does NOT exclude solid organ injury | | Hematuria | Absent | Does NOT exclude renal injury (up to 30–40% of renal injuries have no hematuria) | | Peritoneal signs | Absent | Retroperitoneal injuries may not produce peritoneal signs | ### Why Each Option is Incorrect 1. **Option A — Immediate exploratory laparotomy:** Not indicated in a hemodynamically stable patient without peritoneal signs. Surgery is reserved for hemodynamic instability unresponsive to resuscitation or clear peritoneal signs. 2. **Option B — Observation with selective imaging only if deterioration:** This approach is **outdated and unsafe** for significant blunt flank trauma. Solid organ injuries (e.g., Grade II–III renal laceration, splenic contusion) can be clinically silent initially and progress to delayed hemorrhage. Current ATLS and trauma guidelines recommend CT imaging in stable patients with significant mechanism and flank contusion. 3. **Option D — Prophylactic antibiotics and discharge:** Completely inappropriate. There is no indication for prophylactic antibiotics in blunt trauma without hollow viscus injury, and early discharge without imaging risks missing significant injury. ### ATLS / Trauma Guideline Approach - **Hemodynamically stable + significant blunt abdominal/flank trauma → CT abdomen/pelvis with IV contrast** (ATLS 10th edition) - CT is the gold standard for evaluating solid organ injury in stable patients - Absence of hematuria does NOT exclude renal injury; sensitivity of dipstick for significant renal trauma is limited - FAST ultrasound is useful for detecting free fluid but has limited sensitivity for retroperitoneal injuries ### Imaging Hierarchy in Blunt Abdominal Trauma | Stability | Preferred Imaging | |-----------|------------------| | Unstable | FAST → OR if positive | | Stable with significant mechanism | CT abdomen/pelvis with contrast | | Stable, trivial mechanism, no signs | Observation ± selective imaging | **High-Yield:** The kidney is a retroperitoneal organ — injuries may not produce peritoneal signs or hematuria. A large flank contusion after blunt assault mandates CT evaluation regardless of initial stability. **Clinical Pearl (Harrison's / ATLS 10e):** Up to 30% of significant renal lacerations present without hematuria. CT with contrast remains the definitive imaging modality for grading renal and solid organ injuries in stable trauma patients. **Warning:** Do NOT equate hemodynamic stability with absence of significant injury. Delayed splenic rupture and retroperitoneal hematoma expansion are well-documented complications of initially "stable" blunt trauma. [cite: ATLS 10th Edition, American College of Surgeons; Harrison's Principles of Internal Medicine 21e]