Extended FASTeFAST

Name: Extended FAST (eFAST) — POCUS Tips
Creator: Yonathan Daniel, MD

Free fluid in the abdomen, pericardium and pleural spaces after trauma — a yes/no exam in under three minutes that decides who needs the operating room before the CT scanner.

Open the interactive view with the loop and quiz →

Schematic diagram, not an ultrasound image.

Where to put the probe

Window: Six windows: right and left flanks, suprapubic, subxiphoid, and both anterior chests
Marker: Patient’s HEAD for the flank and pelvic sagittal windows; patient’s LEFT for subxiphoid and the transverse pelvis
probe: curvilinear or phased
preset: abdominal
depth: 15–20 cm

Work the windows

RUQ: probe in the right mid- to posterior axillary line around the 8th–11th rib, marker to the head. Find liver, right kidney and the diaphragm, then look in Morison’s pouch, along the inferior tip of the liver and the paracolic gutter, and above the diaphragm.
LUQ: higher and more posterior than you expect — knuckles on the bed, 6th–9th rib, posterior axillary line. Check the spleen–diaphragm interface first (where fluid collects on this side), then the splenorenal space and above the diaphragm.
Pelvis: suprapubic, transverse then sagittal, using the bladder as a window. Look behind and beside the bladder (rectovesical space, or the pouch of Douglas) and set gain low enough that fluid is black, not gray.
Subxiphoid for pericardial fluid, then both anterior chests for lung sliding. Report each window as positive, negative or indeterminate rather than a single overall ‘negative’.

What you are looking at

Morison’s pouch: The hepatorenal space. Free fluid pools here first in a supine patient — a black stripe between liver and kidney.
Right supradiaphragmatic space: Above the diaphragm from the same window: a black space with the spine visible above the diaphragm means hemothorax.
Spleen–diaphragm interface: On the left, fluid collects between spleen and diaphragm before it reaches the splenorenal space.
Splenorenal space: Between spleen and left kidney; check it after the subphrenic space.
Pericardium: Subxiphoid: a black rim around the heart. In penetrating trauma this is the window that matters most.
Rectovesical space / pouch of Douglas: The most dependent peritoneal space: fluid behind or beside the bladder. Needs a reasonably full bladder to see.
Paracolic gutter: Below the inferior tip of the liver. Fluid here can be the only positive finding.
Pleural line (anterior chest): Lung sliding present at the anterior chest excludes pneumothorax at that point.

On the screen

RUQ window, positive: a thin anechoic stripe between the liver and the right kidney — free fluid in Morison’s pouch. This is what a small positive looks like: a black line where two organs should touch. Image: Ultrasound Idiots

RUQ window, negative: liver and kidney stay in contact through the breath with no anechoic stripe between them. Gray, feathered tissue is fat or parenchyma; free fluid would be black with sharp edges. Image: The POCUS Atlas

RUQ window, positive Morison’s sign: free fluid fills the hepatorenal space (Morison’s pouch) and separates the liver from the kidney. Fluid this abundant is unmistakable — the thin stripe in the first loop is the one people miss. Image: The POCUS Atlas

LUQ window, positive: a black crescent of free fluid between the spleen and the bright diaphragm — the subphrenic space, where fluid collects first on this side — tracking around the splenic tip. Scan high and posterior or you will miss it. Image: Ultrasound Idiots

Decision rules

Finding	Weight	What it means
Free fluid in any abdominal windowblack stripe with sharp edges that follows organ contours	positive	hemoperitoneum until proven otherwise; with hypotension, that is an operative decision
Minimum detectable volumeMorison’s pouch, supine	≈ 200–500 mL	a negative scan does not exclude injury — a small bleed, solid-organ injury without free fluid, or retroperitoneal bleeding are all missed
Pericardial fluidsubxiphoid, any amount	positive	in penetrating chest trauma this is an indication for surgical input now
Absent slidinganterior chest, supine	suggestive	pneumothorax likely; look for a lung point and treat tension clinically
Repeat scanafter 30 min or any change	—	sensitivity rises with serial scans; a single early negative is not final

Don’t be fooled — pitfalls

Perinephric fat is not fluidA hypoechoic (gray, not black) band around the kidney, often symmetric, with no sharp edges. Free fluid is black, forms sharp angles and tracks around organ tips.
The LUQ is where beginners missScanning too low and too anterior finds bowel instead of spleen. Fluid collects above the spleen, not in the splenorenal space, on this side.
An empty bladder hides the pelvisWith a catheter in, clamp it or fill the bladder; without a window, call the pelvic view indeterminate rather than negative.
Fluid is not always bloodAscites, physiologic pelvic fluid in women, urine from a ruptured bladder and bowel contents all look the same. Context decides.
Clotted blood looks like tissueFresh clot is echogenic and can hide alongside solid organs; look for mixed-echogenicity collections and repeat the scan.
Negative FAST, unstable patientBleeding can be retroperitoneal, in the chest, in the pelvis around a fracture, or external. Do not let a negative scan slow the search.

Bad image? Fix it

Rib shadows across the RUQRotate the probe obliquely so it lies along the intercostal space, and ask for a deep breath to bring the liver down.
Cannot find the spleenMove up a space and posterior — the probe should be nearly on the bed — and angle slightly anteriorly through the spleen.
Pelvis is all grayDrop gain; the bladder should be black. Then fan through the whole bladder in both planes.
Subxiphoid blocked by pain or gasUse a parasternal view instead and say which window answered the pericardial question.

So what — what the finding changes

Positive abdomen + hypotensionLaparotomy pathway: activate the trauma team and blood, skip the CT scanner.
Positive abdomen, stableCT with contrast to define the injury; repeat the scan if the patient changes.
Pericardial fluid after penetrating traumaSurgical input now; prepare for pericardiocentesis or thoracotomy per local practice.
Negative scanNot reassuring on its own in a sick patient. Repeat it, scan the chest and pelvis, and keep looking for blood elsewhere.

Related views

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Educational use only. Not for diagnosis or treatment decisions — confirm findings with formal imaging and your own judgment. By Yonathan Daniel, MD · Pathways · Quiz on this view · About · Last reviewed 2026-10-04.