EM Command Center / Bedside Imaging Atlas

Emergency Ultrasound (POCUS) Atlas

Bedside ultrasound algorithms, probe placement coordinates, normal anatomy vs acute pathology comparisons, and acoustic artifacts for emergency medicine rotations and board examinations.

Blunt & Penetrating Torso Trauma Bedside Diagnostic Algorithm

Extended FAST (eFAST) Protocol

The extended Focused Assessment with Sonography for Trauma (eFAST) identifies hemoperitoneum, hemopericardium, pneumothorax, and hemothorax in unstable trauma patients within 60 seconds.

Probe Selection: Curvilinear (2–5 MHz) or Phased Array (1–5 MHz); High-Frequency Linear (5–12 MHz) for thoracic pleura.

1. Right Upper Quadrant (Morison's Pouch)

RUQ-Morison

Probe Placement & Acoustic Window:

Coronal view at 8th–11th intercostal space, mid-to-posterior axillary line. Probe marker pointed toward patient's head.

Normal Appearance:

Bright hyperechoic line of Glisson's capsule separating liver and kidney with NO dark intervening fluid. Diaphragm visible cephalad.

Pathology / Abnormal:

Anechoic (jet black) stripe of free fluid in the hepatorenal space, subdiaphragmatic space, or the inferior pole of the right kidney (most dependent part in supine patient).

The Board Pearl: The inferior pole of the right kidney is the most sensitive area for small fluid collections (as little as 250 mL). Do not mistake the gallbladder or IVC for free fluid.

2. Left Upper Quadrant (Splenorenal View)

LUQ-Splenorenal

Probe Placement & Acoustic Window:

Posterior axillary line at 6th–9th intercostal space ('knuckles against the bed'). Probe marker to head.

Normal Appearance:

Spleen and left kidney closely apposed; left hemidiaphragm visible superiorly.

Pathology / Abnormal:

Anechoic fluid in the subdiaphragmatic space (fluid collects ABOVE the spleen before entering splenorenal recess due to the phrenicocolic ligament).

The Board Pearl: Fluid on the left collects between the diaphragm and spleen first, NOT between spleen and kidney. Aim more posterior and cephalad than the RUQ view.

3. Pelvic View (Suprapubic)

Pelvic-Suprapubic

Probe Placement & Acoustic Window:

Just superior to pubic symphysis. Obtain both transverse (marker to patient's right) and sagittal (marker to head) planes through full bladder.

Normal Appearance:

Anechoic urine-filled bladder with smooth, sharply demarcated walls.

Pathology / Abnormal:

Anechoic fluid posterior to bladder in rectovesical pouch (males) or pouch of Douglas / rectouterine space (females). In collapsed bladder, fluid surrounds dome.

The Board Pearl: Perform this view BEFORE Foley catheter placement; an empty bladder makes pelvic free fluid nearly impossible to visualize.

4. Subxiphoid Pericardial View

Subxiphoid-Pericardial

Probe Placement & Acoustic Window:

Flat against epigastrium angled shallowly toward left shoulder (30-degree angle to skin). Use patient's liver as an acoustic window.

Normal Appearance:

Liver at top of screen; right ventricle resting against left lobe of liver; thin pericardium with no intervening anechoic space.

Pathology / Abnormal:

Anechoic fluid surrounding heart. Right ventricular diastolic collapse indicates cardiac tamponade physiology.

The Board Pearl: Epicardial fat pad is anterior only and moves WITH myocardium; true pericardial effusion is posterior to left ventricle and separates visceral from parietal pericardium.

5. Anterior Thoracic View (Pneumothorax & Hemothorax)

Thoracic-Pleura

Probe Placement & Acoustic Window:

Linear probe at 2nd–4th intercostal spaces, midclavicular line (air rises to top in supine patient). Probe marker to head.

Normal Appearance:

B-mode: shimmering 'ants marching on a line' lung sliding at the pleural line. M-mode: 'Seashore sign' (waves in ocean = subcutaneous tissue; sandy beach = normal aerated lung).

Pathology / Abnormal:

ABSENT lung sliding. M-mode: 'Barcode sign' / 'Stratosphere sign' (parallel horizontal lines with loss of granular beach pattern). Visualizing a 'LUNG POINT' is 100% specific for pneumothorax.

The Board Pearl: Lung sliding rules OUT pneumothorax at that interspace with 100% negative predictive value. A lung point marks the exact boundary where the collapsed lung separates from parietal pleura.

Rapid Ultrasound for Shock & Hypotension Bedside Diagnostic Algorithm

RUSH Protocol for Shock & Hypotension

A systematic 3-step ultrasound evaluation of The Pump (Heart), The Tank (Volume Status), and The Pipes (Vascular Integrity) to diagnose distributive, cardiogenic, hypovolemic, and obstructive shock in under 3 minutes.

Probe Selection: Phased Array (1–5 MHz) for cardiac; Curvilinear (2–5 MHz) for IVC/abdomen/aorta; Linear (5–12 MHz) for DVT.

Step 1: The Pump (Contractility, Tamponade & RV Strain)

RUSH-Pump

Probe Placement & Acoustic Window:

Parasternal Long Axis (PLAX), Parasternal Short Axis (PSAX), and Apical 4-Chamber (A4C).

Normal Appearance:

LVEF > 55%; fractional shortening normal; mitral valve anterior leaflet touches septum in diastole (EPSS < 7 mm); RV is 2/3 the size of LV.

Pathology / Abnormal:

Cardiogenic: Hypokinetic, dilated LV with poor valve excursion. Distributive: Hyperdynamic LV with kissing papillary muscles. Obstructive: Pericardial effusion with RV collapse (Tamponade) OR dilated RV > LV with septal flattening ('D-shaped LV' in PSAX = massive PE).

The Board Pearl: McConnell's sign (akinesia of RV free wall with sparing of RV apex) has 94% specificity for acute massive pulmonary embolism.

Step 2: The Tank (IVC, eFAST & Lung B-Lines)

RUSH-Tank

Probe Placement & Acoustic Window:

Subxiphoid longitudinal view of IVC (entering right atrium, 2 cm from cavoatrial junction); bilateral thoracic lung zones.

Normal Appearance:

IVC diameter 1.5–2.1 cm with > 50% collapsibility index on deep inspiration. Lung: Bilateral horizontal A-lines with normal sliding.

Pathology / Abnormal:

Hypovolemic/Distributive: Completely flat, 'slit-like' IVC with 100% inspiratory collapse. Cardiogenic/Obstructive: Plethoric, non-collapsing IVC (> 2.1 cm with < 50% collapse) + bilateral B-lines ('lung rockets' > 3 per interspace) indicating cardiogenic pulmonary edema.

The Board Pearl: Positive pressure mechanical ventilation REVERSES normal IVC dynamics: inspiration increases IVC size; assess IVC distensibility index instead.

Step 3: The Pipes (Aortic Aneurysm & DVT)

RUSH-Pipes

Probe Placement & Acoustic Window:

Curvilinear probe on epigastrium down to umbilicus (Aorta); Linear probe on groin and popliteal fossa (DVT).

Normal Appearance:

Abdominal aorta diameter < 2.0 cm throughout (outer wall to outer wall). Femoral and popliteal veins collapse completely under gentle probe pressure.

Pathology / Abnormal:

Abdominal Aortic Aneurysm (AAA): Diameter >= 3.0 cm. Aortic Dissection: Floating intimal flap in lumen. DVT: Non-compressible vein with direct visualization of intraluminal hyperechoic clot.

The Board Pearl: Always measure aorta from outer adventitial wall to outer adventitial wall, NOT lumen to lumen (intraluminal mural thrombus masks true diameter).

Acute Visual Loss & Elevated Intracranial Pressure Bedside Diagnostic Algorithm

Ocular Ultrasound & Optic Nerve Sheath

Rapid bedside identification of retinal detachment, vitreous hemorrhage, lens dislocation, and non-invasive measurement of elevated intracranial pressure via optic nerve sheath diameter (ONSD).

Probe Selection: High-Frequency Linear Probe (7.5–15 MHz) in Ophthalmic Preset (low mechanical index).

1. Retinal Detachment vs. Vitreous Detachment

Ocular-Retina

Probe Placement & Acoustic Window:

Copious sterile acoustic gel over closed upper eyelid (tegaderm barrier optional). Gentle touch without pressure.

Normal Appearance:

Posterior chamber is completely anechoic; smooth retina firmly applied to choroid and sclera.

Pathology / Abnormal:

Retinal Detachment: Thick, bright, hyperechoic membrane floating in vitreous space that is FIXED and ANCHORED to the optic disc and ora serrata. Vitreous Detachment (PVD): Thin, wispy, undulating membrane that cross-crosses across optic disc without tethering.

The Board Pearl: Retinal detachments are tethered to the optic disc posterior insertion; posterior vitreous detachments float freely and are NOT anchored to the nerve.

2. Optic Nerve Sheath Diameter (ONSD) for Elevated ICP

Ocular-ONSD

Probe Placement & Acoustic Window:

Transverse plane through center of globe aligning optic nerve perpendicular to ultrasound beam.

Normal Appearance:

Optic nerve sheath diameter < 5.0 mm measured exactly 3 mm posterior to the globe retrobulbar surface.

Pathology / Abnormal:

ONSD > 5.0 mm (or > 5.8 mm in severe intracranial hypertension) indicates increased intracranial pressure (ICP > 20 mmHg) with 95% sensitivity.

The Board Pearl: The optic nerve sheath is continuous with the intracranial subarachnoid space; pressure transmitting into CSF expands the retrobulbar sheath within minutes.

Bedside Venous Thromboembolism Rule-Out Bedside Diagnostic Algorithm

2-Point Lower Extremity DVT Compression

The evidence-based 2-point compression test evaluates the common femoral vein and popliteal vein with 98% sensitivity for proximal lower extremity DVT.

Probe Selection: High-Frequency Linear Probe (5–12 MHz) in Vascular Venous Preset.

1. Common Femoral & Saphenofemoral Junction

DVT-Femoral

Probe Placement & Acoustic Window:

Transverse orientation at inguinal crease. Locate femoral artery (lateral, pulsatile) and common femoral vein (medial). Follow to saphenous confluence.

Normal Appearance:

Complete coaptation of anterior and posterior venous walls under gentle probe compression (vein winks out of sight while artery remains patent).

Pathology / Abnormal:

Failure of vein walls to touch (non-compressibility), with or without direct visualization of hyperechoic intraluminal thrombus.

The Board Pearl: Compression must be performed in TRANSVERSE plane only; longitudinal compression risks sliding off the vein and creating false coaptation.

2. Popliteal Vein Confluence

DVT-Popliteal

Probe Placement & Acoustic Window:

Transverse view in popliteal fossa with patient's knee slightly flexed and hip externally rotated ('frog-leg').

Normal Appearance:

Popliteal vein sits superficial to popliteal artery ('vein on top') and collapses 100% under downward pressure.

Pathology / Abnormal:

Non-compressible popliteal vein indicating proximal deep venous thrombosis requiring immediate therapeutic anticoagulation.

The Board Pearl: Compress every 1 cm from common femoral bifurcation through the deep femoral/femoral junction, and throughout the popliteal fossa to trifurcation.

Emergency Ultrasound (POCUS) Atlas

Extended FAST (eFAST) Protocol

1. Right Upper Quadrant (Morison's Pouch)

2. Left Upper Quadrant (Splenorenal View)

3. Pelvic View (Suprapubic)

4. Subxiphoid Pericardial View

5. Anterior Thoracic View (Pneumothorax & Hemothorax)

RUSH Protocol for Shock & Hypotension

Step 1: The Pump (Contractility, Tamponade & RV Strain)

Step 2: The Tank (IVC, eFAST & Lung B-Lines)

Step 3: The Pipes (Aortic Aneurysm & DVT)

Ocular Ultrasound & Optic Nerve Sheath

1. Retinal Detachment vs. Vitreous Detachment

2. Optic Nerve Sheath Diameter (ONSD) for Elevated ICP

2-Point Lower Extremity DVT Compression

1. Common Femoral & Saphenofemoral Junction

2. Popliteal Vein Confluence

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