Rosen & Barkin's 5-Minute Emergency Medicine Consult (18 page)

General approach to imaging in abdominal trauma:

• Unstable trauma patients:
  
  • Unstable patients should have a bedside ultrasound performed immediately as part of the primary survey (circulation). A positive FAST suggests that intra-abdominal bleeding is the source of hypotension. A negative FAST suggests either a retroperitoneal bleed, blood loss in the field, bleeding from an unstable pelvic fracture, or hemorrhage into another body cavity.
    
  • A surgeon should be consulted immediately to prepare for definitive operative care of the patient.
    
  • Stable trauma patients: The 3 main modes of diagnosing the extent of injury in hemodynamically stable abdominal trauma patients include:
    
    • US: Initial screening test of choice for hemodynamically stable patients. A positive US in the stable trauma patient warns the clinician about the possibility of impending hemodynamic deterioration. CT scan and surgical consult should be rapidly facilitated in this group of patients.
      
    • CT scan: The definitive test for stable abdominal trauma patients. CT scanning will diagnose both solid organ and retroperitoneal injuries better than ultrasound. CT imaging allows a determination of whether an embolization procedure is warranted for hemorrhage control. It is indicated in all stable patients with stab wounds. It is also indicated in patients with gross hematuria, to look for renal injury.
      
    • Diagnostic peritoneal lavage: Currently used infrequently.
      
• Local wound exploration: While frequently used in the past in penetrating abdominal trauma to look for violation of the fascia, it has now also been replaced with CT scanning in the majority of patients (see Diagnostic Tests & Interpretation).
  

• Blood type and screen
  
• CBC
  
• Electrolytes and creatinine
  
• Lipase
  
• UA
  
• EKG
  

• Ultrasound: FAST exam focuses on dependent intraperitoneal areas where blood can accumulate which include: Hepatorenal space (Morison pouch), splenorenal space, suprapubic region (bladder and pouch of Douglas), pericardium
  
  • Advantages:
    
    • Rapid
      
    • Noninvasive
      
    • Can be performed at the patient’s bedside concurrent with evaluation and initial resuscitation
      
    • Does not require contrast agents or ionizing radiation
      
    • Can be repeated in the case of changes in the patient’s hemodynamic status or physical exam
      
  • Disadvantages:
    
    • Operator dependent
      
    • Does not reliably identify solid organ (e.g., spleen and liver lacerations) or retroperitoneal injuries. May be negative with pelvic fractures despite significant hemorrhage. Not sensitive for bowel injury.
      
  • Contraindications:
    
    • Absolute: None
      
    • Relative: Obesity; subcutaneous emphysema
      
  • Positive test:
    
    • Demonstration of free fluid or obvious solid organ injury. ∼600 mL free fluid required in adults for a positive right upper quadrant Morison pouch view. ∼150 mL is required for a positive pelvic/suprapubic view (optimally performed prior to Foley placement).
      
    • Adequate exam includes visualization of the right upper quadrant, left upper quadrant, suprapubic/pelvis, and cardiac areas.
      
• CT scan:
  
  • Advantages:
    
    • Sensitivity of 85–98%, PPV (for detecting need for laparotomy) of 85%
      
    • Provides specific and detailed organ injury information
      
    • May aid in a nonoperative approach to solid organ injuries, which may be managed with observation or interventional radiology mediated embolectomy.
      
    • Allows imaging of adjacent spinal structures to diagnose fracture.
      
  • Disadvantages:
    
    • Costly
      
    • Possible risk: Up to 1 in 2,000 increase in risk of fatal cancer from radiation
      
    • Requires IV contrast (with risk of acute contrast reactions and renal toxicity).
      
    • Isolated diaphragmatic, pancreatic, bowel injuries may be missed, especially if performed immediately after injury.
      
  • Indications:
    
    • Hemodynamically stable patients
      
  • Contraindications:
    
    • Absolute: Pre-existing indication for exploratory laparotomy; hemodynamic instability; previous contrast reaction
      
  • Considerations:
    
    • Many institutions now manage multisystem trauma patients with the “pan–scan,” which includes CT imaging of the head, C-spine, chest, and abdomen/pelvis in 1 session.
      
    • IV contrast is sufficient in the abdominal trauma patient. Oral and rectal contrast is not needed.
      
    • Angiography
      
      • Unstable patients and pelvic fractures
        
      • This approach can embolize vessels from pelvis, spleen, etc. 
        

• Diagnostic peritoneal lavage:
  
  • Advantages:
    
    • Rapid
      
    • Helpful in detecting mesenteric and hollow organ injuries
      
    • May be considered in patients with pelvic fractures and hemorrhage
      
    • Relatively simple to perform
      
    • Sensitivity 87–92%, specificity 82%, PPV 52%, NPV 87%
      
    •  Low complication rate
      
  • Disadvantages:
    
    • Invasive
      
    • Largely replaced by bedside US
      
    • Does not identify specific organ injury
      
    • 1–2% complication rate
      
    • May miss retroperitoneal injuries and intraperitoneal bladder rupture
      
    • High false-positive rates 
      
• Possible indications:
  
  • Hemodynamically unstable patients
    
  • Patients requiring emergent surgery for other conditions (e.g., craniotomy for epidural hematoma)
    
  • Pelvic fractures
    
• Contraindications:
  
  • Absolute: Pre-existing indication for exploratory laparotomy
    
  • Relative: Previous abdominal surgery, severe abdominal distention, pregnancy, pediatric patients
    
• Considerations:
  
  • Foley catheter and nasogastric tube placement is recommended before beginning the procedure.
    
• Contraindications:
  
  • Blood at urethra
    
  • High riding prostate
    
• Positive test:
  
  • Aspiration of >10 mL of blood, bile, bowel contents, or urine
    
  • Diagnostic peritoneal lavage fluid in the urine or chest tube
    
  • Blunt trauma with >100,000 erythrocytes/mm
    ³
    
  • Penetrating trauma >1,000 erythrocytes/mm
    ³
    

See “Abdominal Trauma (Blunt)” and “Abdominal Trauma (Penetrating).”

TREATMENT

All patients with a significant mechanism of injury or suspicion of major trauma should be triaged to a designated trauma center (preferably a Level 1 Center)

• Pediatric patients should be triaged to a pediatric trauma center or to an adult trauma center equipped to manage children.
  
• CT scan should be considered the diagnostic test of choice in children.
  

• In unstable patients, management of the airway, breathing, and circulation with resuscitation of hypovolemic shock and rapid control of major hemorrhage must take precedence.
  
• See “Abdominal Trauma (Blunt)” and “Abdominal Trauma (Penetrating).”
  

• See “Abdominal Trauma (Blunt)” and “Abdominal Trauma (Penetrating).”
  
• Crystalloid IV therapy is generally warranted with significant abdominal injury.
  
• 2 large-bore IV catheters should be placed.
  
• Blood transfusion is indicated for all hemodynamically unstable abdominal trauma patients. O negative or O positive blood can be used in men/women beyond childbearing age.
  
• Hemodynamically unstable trauma patients with altered mental status and inability to protect airway will usually need endotracheal intubation prior to transfer to operating suite.
  

FOLLOW-UP

• All unstable trauma patients require admission to the hospital and most will require surgical management.
  
• Most multisystem trauma patients who also have abdominal trauma will need admission.
  
• Pregnant women >24 wk gestation should be admitted for fetal–maternal monitoring.
  
• Stable trauma patients are divided into 3 classes:
  
  • Gun shot wounds to abdomen: Almost all will require admission. Rate of surgical exploration is high in this category due to elevated risk of organ injury.
    
  • Stab wounds to abdomen: Patients with penetration of fascia will require admission. US, CT, or physical exam will define patients who need operative management.
    
  • Blunt abdominal trauma: US, CT, or exam will define patients who need admission.
    

• Patients with stable hemodynamics during their ED course with a negative evaluation and reliable follow-up may be considered for discharge.
  
• Patients with inability to travel back to the hospital or to contact EMS for aid in case of deterioration must be considered for admission.
  

A small subset of discharged patients may have an undiagnosed injury (most commonly intestinal or pancreatic). Patients must be instructed to return to the ED with worsening abdominal pain, distention, vomiting, or rectal bleeding.

• US can be immediately performed at the bedside concurrent with initial stabilization.
  
• Consider serial US exams. This is especially important if there is a change in the patient’s hemodynamic status or physical exam.
  
• Many stable adult and pediatric trauma patients are now being managed nonoperatively based on CT findings.
  
• “Pan CT scan” decreases missed injury rate but increases lifetime risk of cancer.
  
• With increased use of US and CT, DPL and local wound exploration have become less useful in the evaluation of abdominal trauma.
  
• Pitfalls include:
  
  • Not immediately sending type and screen or checking a pregnancy test
    
  • Sending pregnant women >24 wk gestation home without fetal–maternal monitoring
    

• Bifflm WL, Kaups KL, Cothren CC, et al. Management of patients with anterior abdominal stab wounds: A western trauma association multicenter trial.
  J Trauma.
  2009;66:1294–1301.
  
• Goodman CS, Hur JY, Adajar MA, et al. How well does CT predict the need for laparotomy in hemodynamically stable patients with penetrating abdominal injury? A review and meta-analysis.
  AJR
  . 2009;193.
  
• Rose JS. Ultrasound in abdominal trauma.
  Emerg Med Clin North Am
  . 2004;22(3):581–599.