Abdominal Trauma, Imaging

Abdominal Trauma, Imaging

Description

This is a diagnostic procedure; basis for its use will vary with results of examination.

Diagnosis
Signs and Symptoms

• Abdominal trauma may present in an unstable patient with multiple associated injuries or as an isolated injury in a stable patient with no physical findings.
• Assessment of the abdomen focuses on the need for early surgical management; the diagnosis of specific organ injuries should be handled later.

History

• History should include mechanism of injury, restraint use and type, airbag or helmet use, prehospital vital signs, initial mental status and change in mental status, and any prehospital treatments performed and their effect on patient status.
• AMPLE history (allergies, especially to radiographic contrast agents, medications, past medical history, last meal, events leading up to the injury)

Physical Exam

• Comprehensive physical exam should include complete bodily exposure and perineal and digital rectal exams.
• Abdominal stab wounds should be locally explored after local anesthesia; penetration of the abdominal wall fascia requires further evaluation.
• Caution should be taken because the physical exam is accurate in determining serious abdominal injury in only 45–50% of cases.

Essential Workup

• See Abdominal Trauma (Blunt) and Abdominal Trauma (Penetrating)

Tests

General approach to imaging in blunt abdominal trauma:

• The ideal abdominal imaging study is rapid, inexpensive, sensitive for operative injury; identifies many nonoperative injuries requiring close observation and follow-up; requires minimal training to perform and interpret; and does not exist yet.
• Ultrasound has become the initial screening test of choice for hemodynamically stable patients; it has replaced diagnostic peritoneal lavage in many clinical settings.
• CT scan is the definitive test for most patients, especially children, but requires intravenous contrast material:
• Unstable patients should not be transported for a CT scan.
• Most patients require serial physical examinations and a period of observation even after negative imaging studies.

Imaging

Ultrasound

• Advantages:
• Rapid
• Noninvasive
• Can be performed at patient's bedside
• Does not require contrast agents or ionizing radiation
• Disadvantages:
• Operator dependent
• Does not reliably identify specific organ injury
• Not sensitive enough to exclude all injuries. Serial examination and observation are required if ultrasound is the sole imaging study.
• Is not well suited for penetrating injuries; may miss significant bowel injuries not accompanied by hemoperitoneum
• Does not evaluate spinal or retroperitoneal injuries
• Indications:
• Blunt trauma in either stable or unstable patients
• Contraindications:
• Absolute:
• Pre-existing indication for exploratory laparotomy
• Relative:
• Obesity
• Subcutaneous emphysema
• Positive test:
• Demonstration of free fluid or obvious solid organ injury (approximately 250 mL free fluid required in adults)
• Adequate exam includes visualization of Morrison pouch, pericardium, both paracolic gutters, and the pelvic rectouterine pouch (pouch of Douglas), and exam of the liver and spleen for parenchymal injuries.
• Considerations:
• Positive test result should be followed by CT in a stable patient or by laparotomy in an unstable patient.
• Institutional factors determine which clinical department performs the study.

CT scan:

• Advantages:
• Sensitivity of 85–98%
• Provides specific organ injury information
• Allows for simultaneous reformatting and reconstruction of spinal structures
• Fosters nonoperative approach to solid organ injuries
• Diagnoses retroperitoneal and bony injuries missed by other modalities.
• Disadvantages:
• Requires intravenous contrast (acute contrast reactions and renal failure)
• 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
• Relative:
• Multiple allergies
• Considerations:
• Modality of choice in children
• Many multiple-injury patients require CT imaging of the head, spine, chest, or pelvis; modern equipment provides for rapid scanning of multiple anatomic regions in one session.
• Monitoring must be continued in the CT suite; patients should be accompanied by appropriate medical personnel.
• Water may be substituted for oral contrast, but optimal detection of intestinal injury requires oral contrast and a 2- to 4-hour delay for intestinal opacification.

Diagnostic Procedures/Surgery

• Gunshot wounds to the abdomen require evaluation by a surgeon and will require laparotomy:
• Selective laparotomy is an option for experienced centers.
• Diagnostic peritoneal lavage:
• Advantages:
• Rapid
• Relatively simple to perform
• 97.8% accurate in diagnosing injury
• Disadvantages:
• Invasive
• Does not identify specific organ injury
• 1–2% complication rate
• May miss retroperitoneal injuries and intraperitoneal bladder rupture
• Indications:
• Hemodynamically unstable patients
• Patients requiring emergent surgery for other conditions (e.g., craniotomy for epidural hematoma)
• Stab wounds that penetrate the abdominal fascia
• Contraindications:
• Absolute: pre-existing indication for exploratory laparotomy
• Relative: previous abdominal surgery, severe abdominal distention, pregnancy, pediatric patients
• Nasogastric tube and Foley catheter placement mandatory before beginning procedure
• 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/mm³
• Penetrating trauma >1,000 erythrocytes/mm³
• Considerations:
• Favored in stab wound patients when local wound exploration is confirmatory
• Favored in unstable blunt trauma patients because it may be performed simultaneously with other emergency-basis surgical interventions (e.g., craniotomy for epidural hematoma)
• Must always be accompanied by serial abdominal exams after procedure
• In the presence of pelvic fractures, use supraumbilical location.
• In pregnancy, consider supraumbilical or open technique.
• False-positive results may be obtained if performed >8 hours after injury.

Differential Diagnosis

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

Treatment

Pre Hospital

All patients with a significant mechanism of injury or suspicion of major trauma should be triaged to a facility equipped to manage such injury.

Pediatric Considerations

• 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 as a greater percentage of injuries in children will be managed nonoperatively.
• Diagnostic peritoneal lavage (DPL) is relatively contraindicated.

Initial Stabilization

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

ED Treatment

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

Follow-Up

Disposition

Admission Criteria

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

Discharge Criteria

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

References
1. Amoroso TA. Evaluation of the patient with blunt abdominal trauma: an evidence based approach. Emerg Med Clin North Am. 1999;17-75.
2. Chiquito PE. Blunt abdominal injuries. Diagnostic peritoneal lavage, ultrasonography and computed tomography scanning. Injury. 1996;27:117-124.
3. Pryor JP, Reilly PM, Dabrowski GP, et al. Nonoperative management of abdominal gunshot wounds. Ann Emerg Med. 2004;43(3):344-353.
4. Rose JS. Ultrasound in abdominal trauma. Emerg Med Clin North Am. 2004;22(3):581-599.
5. Stengel D, Bauwens K, Sehouli J, et al. Emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma. Cochrane Database Syst Rev. 2005;18(2):cd004446.

Miscellaneous
SEE ALSO: Abdominal Trauma, Blunt; Abdominal Trauma, Penetrating
Codes
N/A