Abdominal Trauma

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

• The Hemorrhagic Cascade: The principal cause of shock in trauma is blood loss. The peritoneal cavity can conceal massive volumes of hemorrhage. Crucially, a patient's systolic blood pressure may not drop until 30% to 40% of their total blood volume has been lost, meaning isolated tachycardia might be the only early indicator of impending hemodynamic collapse.
• Blunt Shear & Crush: In blunt abdominal trauma, solid organ lacerations (spleen, liver) cause rapid hemorrhage, but hollow viscus injuries present a unique danger. When a patient is subjected to rapid deceleration (often indicated by a seatbelt sign), the gastrointestinal tract is violently compressed against the spine. This shear force causes "bucket handle tears" where the mesentery physically shears away from the bowel, leading to bowel necrosis and delayed peritonitis over 24 to 72 hours.
• Penetrating Tissue Disruption: The severity of penetrating trauma is directly related to the kinetic energy transfer—specifically, the velocity and depth of penetration. Uncontrolled injury to the aorta, vena cava, or major mesenteric vessels causes immediate exsanguination.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• The Primary Survey: Immediately initiate the ATLS systematic ABCs (Airway, Breathing, Circulation). Rapidly control any identified life-threatening compressible external hemorrhage before moving to internal cavities.
• Volume Resuscitation: In the hypotensive patient, activate the massive transfusion protocol. Administer balanced blood products (un-crossmatched O-negative or O-positive depending on local protocol) rather than relying on crystalloid fluids, which can exacerbate coagulopathy.
• The Unstable Pelvis Adjunct: If the patient presents with concomitant abdominal and pelvic trauma with hemodynamic instability, apply an external pelvic compression device (pelvic binder) immediately. Center the binder over the greater trochanters to reduce pelvic volume and tamponade venous bleeding.
• Surgical Trigger: Emergent surgical consultation must be obtained simultaneously with resuscitation for any patient presenting with frank peritonitis, evisceration, or shock.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

• Critical "Can't-Miss" DDx (Medical Mimics):
• Ruptured Abdominal Aortic Aneurysm (AAA): Can present with profound shock and a tender abdomen, mimicking trauma.
• Ruptured Ectopic Pregnancy: Always assume this in a hemodynamically unstable female of reproductive age with free intraperitoneal fluid.
• Severe Medical Peritonitis: Such as perforated viscus (e.g., peptic ulcer disease) or mesenteric ischemia.
• Prioritized Workup:
• eFAST (Extended Focused Assessment with Sonography for Trauma): The immediate bedside gold standard for detecting intraperitoneal fluid.
• CT Abdomen/Pelvis with IV Contrast: The imaging modality of choice for characterizing solid organ injuries, hollow viscus damage, and retroperitoneal injuries—only if the patient is hemodynamically stable.
• Local Wound Exploration (LWE): For anterior abdominal stab wounds in stable patients, used to determine if the peritoneal fascia has been violated.
• Diagnostic Peritoneal Aspirate/Lavage (DPA/DPL): Occasionally used to evaluate for hemorrhage or hollow viscus injury if ultrasound is equivocal or unavailable.

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

• Physical Exam (The Seatbelt Sign): Look for ecchymosis across the abdomen. This visually confirms a compromised occupant-seatbelt relationship and mandates high suspicion for bowel/mesenteric injuries.
• POCUS (eFAST) "Look-Fors":
• Right Upper Quadrant: Check Morison's pouch (hepatorenal recess) for an anechoic (black) stripe of free fluid.
• Left Upper Quadrant: Evaluate the perisplenic space and splenorenal recess.
• Suprapubic View: Look for free fluid settling in the pouch of Douglas (retrovesical space).
• CT Imaging: Look for signs of solid organ laceration (splenic/hepatic contrast pooling), free air (pneumoperitoneum indicating viscus rupture), or mesenteric stranding/hematoma indicating a bucket handle tear.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

• The Blunt Abdominal Trauma (BAT) Algorithm:
• Hemodynamically Unstable + Positive eFAST (or DPL) $\rightarrow$ Immediate Laparotomy.
• Unstable Pelvis + Positive eFAST $\rightarrow$ Operating room for emergent laparotomy.
• Unstable Pelvis + Negative eFAST (and no other source of bleeding) $\rightarrow$ Interventional Radiology (IR) for emergent pelvic angiography and embolization.
• The Anterior Abdominal Stab Wound Algorithm (Western Trauma Association):
• Hemodynamic instability, peritonitis, or evisceration $\rightarrow$ Immediate Laparotomy.
• Stable $\rightarrow$ Perform Local Wound Exploration (LWE). If LWE definitively proves the peritoneum is not violated, the patient can be safely discharged from the ED. If violated, proceed to CT, Serial Physical Exams (SPEs), or laparoscopy.

6. THE DANGER ZONE (Pitfalls & Critical Actions)

• The "CT Scanner of Death" Trap: Sending a hemodynamically unstable trauma patient with a positive eFAST to the CT scanner is a lethal error. These patients require the operating room, not radiology.
• False Reassurance with Normal Vital Signs: Do not rule out major hemorrhage just because the blood pressure is normal. Remember that up to 40% of blood volume can be lost before hypotension manifests.
• Premature Closure with a Negative CT: In patients with a seatbelt sign, a negative CT scan does not completely rule out a hollow viscus or bucket handle tear. While modern CT scanners have a near-zero miss rate, strict return precautions and serial monitoring for nausea, vomiting, or pain are still mandated due to the risk of delayed bowel necrosis.

7. MCQ MASTERCLASS (Written Exam Tips)

• High-Yield "Buzzwords": A stem describing a "seatbelt sign" on the abdomen after an MVC points directly to bucket handle tears or hollow viscus injury.
• Common Distractor: A patient presents in hypotensive shock after blunt trauma, and an eFAST shows free fluid in Morison's pouch. The distractors will offer "CT Abdomen/Pelvis" or "Diagnostic Peritoneal Lavage." The only correct answer is emergent laparotomy.
• Stab Wound Triage: A stable patient with an anterior stab wound has a negative LWE showing intact anterior fascia. The question will ask for the next step. The correct board answer is discharge, bypassing DPL or CT.

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

• Mandatory Physical Exam Maneuvers: Verbally announce: "I am initiating the primary survey. I will assess the airway, auscultate bilateral breath sounds, and expose the abdomen to look for penetrating wounds, evisceration, or a seatbelt sign. Concurrently, I am applying the ultrasound probe for an immediate eFAST exam."
• The Script (Unstable Patient): "Examiner, the patient is hemodynamically unstable following blunt abdominal trauma. The eFAST demonstrates anechoic fluid in Morison's pouch. I am immediately activating the massive transfusion protocol, applying a pelvic binder to rule out pelvic expansion, and consulting trauma surgery for a stat exploratory laparotomy. The patient will not go to the CT scanner."