The following is an overview of the 4 main steps involved during a basic FAST examination in a post-traumatic patient.

FAST stands for "Focused Assessment with Sonography in Trauma". It's a fundamental, non-invasive ultrasound procedure used to quickly detect the presence of free fluid around the heart, in the abdomen, and in the pelvis.

Note - In the context of traumatic injury, this fluid will usually be due to bleeding.

The four classic areas that are examined for free fluid are the right upper quadrant (RUQ), also called Morison's pouch or the hepatorenal recess), as well as the perisplenic space, pericardium, and the pelvis.

For the RUQ view, place the probe in approximately the mid-axillary line in the 7th to 9th intercostal space with the probe marker facing toward patients head.
Move the probe superiorly and inferiorly along mid-axillary line, fanning anterior to posterior at each position.

Normal views of the RUQ (ie, no free fluid) - bright, hyperechoic line separating liver from the kidney.

The specific landmarks in this view are the liver, diaphragm, inferior pole of right kidney, and Morison’s Pouch (hepatorenal recess).

Pearl - The hepatorenal recess (Morison's pouch) is the potential space located between Glisson's capsule of the liver and Gerota's fascia of the right kidney.

Note - Morison’s Pouch is actually not typically the first place to see free fluid. The "Money Shot” is actually the right lateral paracolic gutter, or space between colon and abdominal wall located just inferior to the liver's edge, as it is the most dependent area when patient is in supine position.

For the subxiphoid (or pericardial) view, position the probe just below xiphoid, laying the probe almost horizontal to the patient’s abdomen with the probe marker positioned at 9 o’clock in reference to the patients head.
From here, fan the probe L and R until you obtain the subxiphoid view.

Normal views of the cardiac window (ie, no free fluid).

One mistake examiners often make in this view is not lying the probe horizontal enough, causing probe to capture the area posterior to the heart.

You should also note the the heart is at least 6cm from subxiphoid so always bring depth out to maximal level for this view.

Pericardial effusion in the acute setting can be due to trauma. Remember, slow accumulation of fluid in patients with renal failure can often mimic a traumatic setting.

One trick to obtaining this view in a stable patient is to have them bring their knees up to relax the abdominal muscles, allowing for a better view.

For the LUQ view (or splenorenal recess), position the probe in approximately the 5th-7th intercostal space with the probe marker facing the patient's head.

This view is best obtained just posterior to the mid-axillary line by moving superior to inferior, fanning anterior to posterior at each position.

Normal views of the RUQ (ie, no free fluid) - bright, hyperechoic line separating spleen from the kidney.

Note that the splenorenal space, and the inferior pole of the left kidney lie higher in the abdominal cavity than the hepatorenal space and inferior pole of right kidney due to the smaller size of the spleen compared to the liver.

Note - the first place fluid typically accumulates is between spleen and diaphragm (not spleen and kidney).

The LUQ view is often difficult to obtain due to “stomach sabotage”, or the accumulation of free air in the stomach, obstructing a clear view.

For the pelvic view, position the probe just above pubic symphysis in both the transverse (shown in image) and longitudinal planes with the probe marker either at 9 o’clock in transverse (as shown) or toward he patient's head in longitudinal view as the bladder is not always midline above the pubic symphysis.
Fan the probe either superior and inferior in the transverse view or left to right in the horizontal view.
Important - look in both transverse and longitudinal planes as the longitudinal (saggital) is more sensitive for small quantities of fluid.

Pearl - this view is best obtained with a full bladder, before a foley is placed

Normal views of the pelvis (ie, no free fluid) in a female.

Landmarks:
Retrovesical pouch (M) - rectum to bladder
Retrouterine pouch (F) - rectum to uterus

Tip - The most common reason to miss the bladder is either a probe too superior to the pubic symphysis or an empty bladder in which case you may consider injecting saline via a foley catheter to enlarge the bladder.

Link to Video: www.youtube.com/watch?v=BLYKuSjhrO8

The following is the typical algorithm used following FAST assessment in a traumatic setting.