A 32-year-old man is brought to the emergency department following a high-speed motor vehicle collision. On arrival, he is alert and oriented, speaking in full sentences. Vital signs: BP 128/82 mmHg, HR 104/min, RR 22/min, SpO₂ 96% on room air. Primary survey reveals clear bilateral breath sounds, no external bleeding, and a soft abdomen. During the secondary survey, you palpate a tender left flank with ecchymosis. The patient reports left-sided rib pain and mild dyspnea. What is the most appropriate next step in the management of this patient's flank injury?

Explanation

## Clinical Context This patient is **hemodynamically stable** following a high-speed motor vehicle collision with a blunt left flank injury. He has left flank tenderness, ecchymosis, left-sided rib pain, and mild dyspnea — all signs pointing to significant energy transfer to the left flank/retroperitoneum, raising concern for solid organ injury (spleen, kidney, adrenal) and/or rib fractures with associated complications. ## Management Approach in Stable Blunt Trauma **Key Point:** In a **hemodynamically stable patient** with blunt abdominal/flank trauma and clinical findings suggesting possible solid organ injury, **CT scan of the abdomen and pelvis with IV contrast** is the most appropriate next step. This is the gold-standard imaging modality in stable trauma patients and is explicitly recommended by ATLS (10th Edition) for evaluation of blunt abdominal trauma when the mechanism and physical findings warrant concern. **High-Yield:** The ATLS protocol and current trauma surgery guidelines support CT imaging in stable patients when: - Mechanism is high-energy (high-speed MVC) - Physical findings suggest organ injury (flank ecchymosis, tenderness, rib pain) - Reliable clinical examination alone is insufficient to exclude significant injury Observation alone (serial exam without imaging) is appropriate only for **truly low-risk** blunt trauma with minimal mechanism and no localizing findings. This patient's high-speed mechanism, ecchymosis, and rib tenderness mandate imaging. ## Why Each Option | Option | Rationale | | --- | --- | | **Serial exam + selective imaging only if deterioration** | Incorrect in this context. The mechanism (high-speed MVC) and physical findings (flank ecchymosis, tenderness, rib pain) are sufficient indication for CT now, not only if the patient deteriorates. Waiting risks missing a significant injury that could decompensate. | | **DPL** | Invasive and largely obsolete in modern trauma care; CT is superior in stable patients and provides anatomic detail DPL cannot. | | **Immediate CT abdomen/pelvis with IV contrast** | **CORRECT.** CT with IV contrast is the standard of care for evaluating blunt abdominal/flank trauma in hemodynamically stable patients. It identifies solid organ lacerations (spleen, kidney, liver), retroperitoneal hematoma, rib fractures, and vascular injuries, guiding non-operative vs. operative management. | | **Exploratory laparotomy** | Reserved for hemodynamically unstable patients not responding to resuscitation, or those with clear peritoneal signs. Premature surgery in a stable patient increases morbidity. | ## Clinical Pearl **CT abdomen/pelvis with IV contrast is the investigation of choice** in hemodynamically stable blunt trauma patients with concerning mechanism or physical findings. It allows grading of solid organ injuries (e.g., AAST splenic/renal laceration grades) and guides selective non-operative management. Serial examination alone is insufficient when the mechanism and findings are significant. ## Key Monitoring Parameters - Perform CT promptly while monitoring vitals - Urine output (target >0.5 mL/kg/h) — hematuria may indicate renal injury - Serial vital signs during and after imaging - Hemoglobin trend (serial CBC) - Any hemodynamic deterioration → reassess for operative intervention [cite: ATLS 10th Edition, Chapter 5: Abdominal and Pelvic Trauma; Cameron's Current Surgical Therapy, Blunt Abdominal Trauma]