MD Notes

creation date: 2025-12-30 18:57
tags: InterventionsIncomplete

Extended Focused Assessment with Sonography in Trauma (eFAST)

Background

Purpose and Indications

Traumatic injury is a leading cause of death and in 80% of cases, mortality is linked to subsequent hypovolemic shock. The eFAST is highly sensitive and specific in detecting intraperitoneal bleeds without need of radiation or contrast agent. The eFAST adds views to the original FAST exam for hemothorax and pneumothorax above the diaphragm.

The eFAST is indicated in cases of:

  • Blunt and/or penetrating abdominal and/or thoracic trauma
  • Undifferentiated shock and/or hypotension (as part of the Rapid Ultrasound for Shock and Hypotension (RUSH) exam)
  • Unstable vitals in which immediate CT is not possible

eFAST looks to address the following:

  • Is there free fluid in the peritoneal cavity?
  • Is there pericardial effusion?
  • Is there fluid in the pleural space (hemothorax)?
  • Is there bilateral lung sliding or lung point (pneumothorax)? – both traumatic or spontaneous
  • Is there ruptured ovarian cyst?

Equipment

A low frequency 2-5 MHz such as the curvilinear probe (“abdominal probe”) is used for the exam. It is generally preferred to use one probe for the entire exam to avoid switching transducers.

In some cases, the cardiac probe may be preferred for the cardiac view although rarely necessary unless the chambers of the hearts are being viewed.

A high frequency probe (10 MHz) may allow for the lung views to be better visualized.

Views

The eFAST consist of an abdominal scan (for blood in peritoneum), cardiac scan (for pericardial effusion), and lung scan (for hemothorax and pneumothorax).

Practically, scanning for hemothorax occurs with the abdominal scan due to there proximity.

Limitations

The eFAST does not replace other means of imaging or diagnostic ultrasound.

Abdominal Scan

False positives:

  • Perinephric fat (usually more echogenic but may be darker in some people) – proportional to body habitus and usually bilateral
  • Physiologic fluid in rectouterine pouch
  • Prostate/seminal vesicles

Fluid imitators:

  • Ascites
  • Urine
  • Peritoneal dialysis fluid
  • Intraluminal bowel fluid

False negatives:

  • Adhesions (sequester fluid in atypical places; caution if significant abdominal surgery history)
  • Small amounts of fluid/early presentation (repeat scan if high suspicion)
  • Delayed presentation (clot no longer shows up as free fluid)
  • Poor technique/inexperienced provider

Cardiac Scan

False positives:

  • Anterior cardiac tissue fat pad (only visible anteriorly, also more echogenic)

False negatives:

  • Delayed presentation (clot no longer shows up as free fluid)
  • Poor technique/inexperienced provider
  • Loculated cardiac effusions

Lung Scan

False positives:

  • Main stem intubation (left lung not ventilated and thus no lung sliding)
  • Pleural adhesion
  • ARDS
  • Pulmonary contusions
  • Bullous disease
  • Pulmonary fibrosis

False negatives:

  • Loculated pneumothorax (on the side or posterior)

Technique

Right Upper Quadrant (RUQ)

This is the most dependent position within the peritoneum.

External landmark:

  • Mid-axillary line
  • Level of xiphoid process

Internal landmark:

  • Hepatorenal interface (Morison’s pouch)
  • Diaphragm

Steps

  1. Place indicator to patient’s head
  2. Position for the interface between liver and kidney (Morison’s pouch)
  3. Sweep the interface until the kidney disappears on anterior and posterior sides
  4. Rock the probe caudally for the caudal tip of the liver (where fluid will accumulate first) and sweep again (if not visualized from first sweep of kidney)
  5. Rock cephaladly for the diaphragm
    • Indeterminate: curtain sign (lateral lung curtain from breath) and non-visualized spine (air-filled lungs do not show far-field spine cephalad to diaphragm)
    • Hemothorax: spine sign – spine visualized into pleural cavity (fluid transmit beam), jellyfish sign (atelectactic lung hanging into hemothorax)

Example Images

Morison’s pouch, normal:

Morison’s pouch, free fluid:

Caudad tip of liver, free fluid:

Diaphragm, normal:

Diaphragm, hemothorax:

RUQ, free fluid in Morison’s pouch and hemothorax:

Left Upper Quadrant (LUQ)

Although less dependent than RUQ, LUQ contains the spleen which is most likely to be ruptured in traumatic injury, albeit fluid moves away. Least likely position for free fluid to accumulate but done second as the gain/depth settings will match RUQ.

External landmark:

  • Posterior axillary line
  • Level of xiphoid process

Internal landmark:

  • Splenorenal interface
  • Diaphragm

Steps

  1. Place indicator to patient’s head
  2. Position probe to visualize spleen and kidney (see below)
  3. Check the following 3 determinate positions; fluid in any results in a determinate scan (negative in all 3 is non-determinante):
    • Subdiaphragmatic space (visualize the diaphragm from the 6 to 9 o’clock region)
    • Caudal tip of spleen
    • Entire splenorenal interface (sweep anteriorly and posteriorly until kidney disappears)
  • Scan the diaphragm for hemothorax (see RUQ)

Example Images

Splenorenal, normal:

Diaphragm, 6 to 9 o’clock:

Splenorenal/subdiaphragmatic space, free fluid:

Splenorenal/caudal spleen tip, free fluid:

Pelvic

The pelvis is the next most dependent position after the RUQ. There are two views: longitudinal and transverse.

External landmark:

  • Cephalad to pubic symphysis
  • Midline bladder

Internal landmark:

  • Bladder

Indicator:

  • Longitudinal: cephalad
  • Transverse: patient’s right

Steps

  1. Position probe to find bladder
  2. Scan/rock on short axis of the probe until bladder fully disappears on either side
  3. Repeat for both longitudinal and transverse views

Male:
3. Look posterior-inferior (far-field) of the bladder

Female:
3. Look at rectouterine pouch (pouch of Douglas) – note: reproductive age female may have some normal free fluid here, but should not be anywhere else
4. Look at vesicouterine pouch

Example Images

Longitudinal, male, normal:

Longitudinal, male, free fluid:

Longitudinal, female, normal:

Longitudinal, female, free fluid in rectouterine pouch (far field) and partially vesicourterine pouch (red marker):

Transverse, male, normal:

Transverse, male, free fluid:

Transverse, female, normal:

Transverse, female, free fluid in rectouterine pouch (red marker on uterus):

Subxiphoid

Assess for cardiac tamponade or pericardial effusion. Note, cardiac tamponade is determined clinically as the eFAST does not analyze for signs of tamponade.

External landmark:

  • Mid-abdomen below xiphoid
  • Probe flat, beam angled to left shoulder
  • Indicator to patient’s right

Internal landmark:

  • Inferior pericardium of the heart

Steps

  1. Place probe, aiming the beam through the liver (liver window); stomach will hide heart due to air bubble
  2. Visualize the inferior pericardium from the end of the diaphragm (where RA begins) to the interventricular septum (landmark: “7 sign”)
  3. Sweep anterior-posterior until heart disappears on both sides
  4. If difficult to visualize:
    • Have patient take deep breath (moves heart down)
    • Have patient bend knees (moves abs down for probe to push deeper)
    • Move probe slightly left and aim right for better liver window

Example Images

Inferior pericardium, normal:

Inferior pericardium, pericardial effusion (red marker):

Anterior Thoracic

Scan for pneumothorax.

External landmark: anterior intercostal spaces in mid-clavicular line
Internal landmark: ribs, pleural line
Probe: curvilinear or linear
Indicator towards patient’s head

Steps

  1. Visualize between the ribs and the pleural lines, just far-field of the ribs
  2. Sweep left and right until the probe is perpendicular to the pleural line (not chest wall) – pleural line will be brightest and crispiest
  3. Observe for lung sliding at pleural line (ants on a line) with respiration – lack of lung sliding indicates pneumothorax
  4. Check with M mode: sandy beach is indeterminate, barcode is pneumothorax
  5. Repeat for both sides of the lung and check 2-3 different intercostal spaces inferiorly (note, air accumulates anteriorly in a supine patient)

To confirm the absence of lung sliding is due to pneumothorax and not another cause, the lung point can be checked. This is the point at which the lung goes from non-sliding to sliding which is present with pneumothorax. (Not applicable to complete pneumothorax).

Example Images

Anterior lung, normal:

See video examples for lack of lung sliding (difficult to appreciate with still image)

Interpretation

For the abdominal and cardiac views:

  • If any views are positive: FAST positive
  • If all views are negative: FAST negative
  • If there are any indeterminate views: indeterminate

The lung scans are documented separately for:

  • Presence/absence of pneumothorax and/or hemothorax

References

Tools / Guidelines

The POCUS Atlas

Additional Reading

Backlinks