What is the role of Focused Assessment Sonography in Trauma (FAST) in evaluating patients with suspected internal bleeding?

From the Guidelines

Focused Assessment Sonography in Trauma (FAST) is a crucial diagnostic tool for identifying internal bleeding in trauma patients, and its use is recommended as part of the initial trauma assessment, particularly in hemodynamically unstable patients. The FAST exam evaluates four specific areas: the perihepatic space (right upper quadrant), perisplenic space (left upper quadrant), pelvis, and pericardium. This non-invasive procedure can be performed within minutes, allowing clinicians to quickly determine if a patient has hemoperitoneum or hemopericardium without moving them from the resuscitation area.

Key Points

• The sensitivity of FAST ranges from 75-95% for detecting intraperitoneal fluid, though it may miss small amounts of blood (less than 100-200 mL) and has limitations in detecting specific organ injuries 1.
• In hemodynamically unstable patients with positive FAST results, immediate surgical intervention is often warranted, while stable patients with positive findings typically undergo further diagnostic imaging such as CT scans 1.
• The exam requires minimal equipment and can be performed by emergency physicians, surgeons, or radiologists with appropriate training, making it particularly valuable in resource-limited settings or mass casualty situations 1.
• FAST has largely replaced diagnostic peritoneal lavage in many trauma centers due to its speed, non-invasiveness, and ability to be repeated as needed.

Limitations and Considerations

• The level of evidence for FAST remains low, and further comparative studies are required on the diagnostic, prognostic, and decision-making impact in the prehospital field 1.
• The diagnostic performance of FAST may be inferior to intrahospital FAST, and its feasibility may be impeded by poor conditions, obesity, and low operator experience 1.
• A negative result of a FAST exam may not rule out slowly accumulating intra-abdominal free fluid, and a retroperitoneal hematoma can generate intra-abdominal effusion, particularly in patients with complex pelvic injury 1.

Recommendations

• FAST should be used as part of the initial trauma assessment, particularly in hemodynamically unstable patients, to quickly identify internal bleeding and guide further management.
• In stable patients with positive FAST findings, further diagnostic imaging such as CT scans should be considered to evaluate the extent of injuries.
• The use of FAST should be integrated into a comprehensive trauma assessment, including clinical evaluation, laboratory tests, and other diagnostic imaging modalities, to ensure optimal patient outcomes.

From the Research

Role of Focused Assessment Sonography in Trauma (FAST)

• FAST is a limited ultrasound examination aimed at identifying the presence of free intraperitoneal or pericardial fluid in patients with suspected internal bleeding 2.
• The primary goal of FAST is to detect free fluid, which is usually due to hemorrhage, bowel contents, or both, and to contribute to the timely diagnosis of potentially life-threatening hemorrhage 2.
• FAST is a rapid, reliable, and feasible investigation in patients with blunt trauma abdomen, and it can be performed easily, safely, and quickly in the emergency room with a reasonable sensitivity, specificity, and accuracy 2, 3.

Diagnostic Accuracy of FAST

• The sensitivity, specificity, and accuracy of FAST in detecting free fluid have been reported to be around 69.8-80.4%, 75-100%, and 79-80.8%, respectively 2, 4, 5.
• FAST has been shown to be an important tool in the initial assessment of suspected blunt abdominal injury patients with high sensitivity and specificity 4.
• However, a negative FAST result does not exclude low-grade solid visceral or other injuries, and should always be confirmed by other modalities 4, 5.

Limitations and Controversies

• The actual value of FAST in the diagnostic and treatment pathway of patients with blunt abdominal trauma remains questionable, and more data are needed to justify its use 6.
• The operator dependence of ultrasound, improved access to CT scans, and variations in practice and education may limit the effectiveness of FAST 6.
• Despite these limitations, FAST remains a widely recognized and essential part of emergency department services, particularly in the management of hemodynamically unstable patients 3, 5.