What is the role of EFAST (Extended Focused Assessment with Sonography for Trauma) in trauma care?

The Role of EFAST in Trauma Care

EFAST (Extended Focused Assessment with Sonography for Trauma) is a critical initial imaging tool in trauma care that rapidly detects free fluid in peritoneal, pleural, and pericardial spaces, enabling early identification of bleeding sources when CT scanning is not immediately possible due to hemodynamic instability. 1

Primary Functions and Diagnostic Performance

• EFAST serves as a rapid bedside ultrasound technique compatible with ongoing resuscitation efforts in hemodynamically unstable patients 2, 1
• When combined with chest X-ray, EFAST enables appropriate urgent intervention decisions with 98% accuracy in hemodynamically unstable patients 2
• For intra-abdominal bleeding detection in pelvic trauma associated with severe abdominal trauma, EFAST has a positive predictive value of 97% 2
• The negative predictive value of EFAST is 97% in patients with shock, making it valuable for ruling out certain injuries 2
• EFAST has high specificity (99% for pneumothorax, 94% for pericardial effusion, 98% for intra-abdominal free fluid) but more moderate sensitivity (69% for pneumothorax, 91% for pericardial effusion, 74% for intra-abdominal free fluid) 3

Clinical Decision-Making Based on EFAST Results

• When EFAST and chest X-ray rule out extra-pelvic causes of hemorrhagic shock in pelvic trauma, patients should undergo body CT scan with intravenous contrast followed by angiography/embolization 2
• The abundance of hemoperitoneum detected on EFAST correlates with the need for laparotomy - 3 positive EFAST sites is associated with 61% appropriate laparotomies, while 2 positive sites correlates with 26% 2
• In rare cases of uncontrollable hemorrhagic shock, angiography/embolization can be performed immediately after EFAST and chest X-ray to rule out non-pelvic massive hemorrhage 2
• EFAST is particularly useful as a rule-in tool for pneumothorax, pericardial effusion, and intra-abdominal free fluid, but its limitations as a rule-out tool must be recognized 3

Integration with Other Imaging Modalities

• In hemodynamically stable patients, EFAST should be followed by a thoraco-abdomino-pelvic CT scan with contrast for complete injury assessment 2
• In hemodynamically unstable patients, EFAST combined with pelvic and chest X-rays may be the only imaging workup possible during ongoing resuscitation 2
• CT scan with intravenous contrast remains the gold standard for hemodynamically stable trauma patients 2

Limitations and Pitfalls

• EFAST performance may be diminished by false positives such as suffusion of a hemoretroperitoneum or intra-peritoneal bladder rupture 2
• The negative result of a very early EFAST may not rule out slowly accumulating intra-abdominal free fluid 2
• A retroperitoneal hematoma can generate intra-abdominal effusion, particularly in patients with complex pelvic injury 2
• EFAST is not recommended to rule out specific intra-abdominal injuries 2
• Poor documentation and technically limited/incomplete studies can affect up to 29.8% of EFAST exams 4
• Common sources of errors include pelvic fluid, double-line sign, pericardial fat pad, and the thoracic portion of the EFAST exam 4

Clinical Applications in Different Settings

• EFAST is valuable in resource-limited settings such as intensive care units in war zones, rural or distant places where other imaging methods are not available 5
• EFAST can replace diagnostic peritoneal lavage and does not delay surgical procedures when performed properly 5
• EFAST should be integrated into the "ABCDE" resuscitation protocol for trauma patients 6
• EFAST is reliable even when performed by non-radiological personnel, saving time and resources in emergency environments 6

Recommendations for Implementation

• EFAST should be performed on admission to the hospital to rule in or out free intra-abdominal fluid and to rule out more than 500 ml of free fluid if the exam is negative 2
• Clinical signs alone are insufficient to rule in or rule out abdominal injury, making EFAST an important adjunct in trauma assessment 2
• EFAST should not delay rapid transfer to an appropriate center and can be repeated during transport 2