A bedside ultrasound companion for the emergency department.
Twelve illustrated visual guides covering foundations, focused scans, integrated protocols, and advanced measurement — built for revision before a shift, on the move, or while you're learning the probe.
Right image · right patient · right time.
A focused, question-driven approach to bedside ultrasound. Each module opens with a complete visual guide, supplemented by interactive calculators and structured key points.
Each guide follows the same arc — indications, probe & setup, scan windows, key findings, pitfalls — so the curriculum feels familiar across modules and easy to revise.
Start here
Cognitive frameworks · scan-by-syndromeThe POCUS mindset
Six steps every scan: clinical question → probe → acquire → interpret → integrate → action. The cognitive skeleton.
Scan by syndrome
RUSH · CLUE · eFAST · Arrest POCUS — with pattern → diagnosis maps for the undifferentiated patient.
Errors that kill scans
The cognitive shortcuts that lead to misdiagnosis — and the corrective rule for each.
Foundations atlas
Physics · knobology · artefactsThe physics behind every image
Frequency, impedance, attenuation, echogenicity — why probes see what they see.
Dials that change diagnosis
Depth, gain, TGC, focus — the controls that turn a fuzzy scan into a diagnostic one.
Artefacts atlas
A-lines, B-lines, mirror, comet, shadow, enhancement — what's diagnostic, what to ignore.
Core foundations
View all 12 →Integrated protocols
Advanced & specialised
All twelve guides.
The complete illustrated POCUS curriculum — each card opens the full visual guide with interactive calculators, key points, and pitfalls.
Module title
Module subtitle.
POCUS Calculators
Educational calculators for bedside ultrasound — measurements, classifiers, and quick-reference tools across cardiac, vascular, renal, obstetric, and ocular applications. Confirm with the rest of the clinical picture; values are decision aids, not decisions.
Ejection fraction · six methods
Cardiac · LV / RVEyeball EF
Rapid bedside qualitative read across multiple views (PLAX, PSAX, A4C). Useful for triage and trend tracking; should be confirmed with quantitative methods when image quality is adequate.
EPSS — E-Point Septal Separation
M-mode through the mitral valve in PLAX. Distance from anterior mitral leaflet (E-point) to interventricular septum at peak diastole. Larger separation correlates with poorer LV function.
EF ≈ 75.5 − (2.5 × EPSSmm) — rule of thumb only
EPSS > 7 mm suggests reduced EF; > 13 mm strongly suggests severe dysfunction.
Simpson's biplane
The reference-standard 2D method. Trace LV endocardial border in A4C and A2C at end-diastole and end-systole. Disk-summation calculates volumes.
EF (%) = (EDV − ESV) / EDV × 100
Teichholz & fractional shortening
From M-mode in PLAX at chordae level. Less accurate with regional wall motion abnormalities — assumes symmetric contraction.
FS = (LVIDd − LVIDs) / LVIDd × 100
Teichholz EDV = 7×LVIDd³ / (2.4 + LVIDd)
MAPSE — longitudinal LV
Mitral Annular Plane Systolic Excursion. M-mode at the lateral mitral annulus in A4C — measures longitudinal LV systolic motion. Independent of geometric assumptions; quick screen for LV systolic dysfunction.
≥10 mm normal · 7–9 mm mild · 5–7 mm moderate · <5 mm severe dysfunction.
FAC — fractional area change (RV)
The RV equivalent of EF. Trace RV endocardial border in RV-focused A4C at end-diastole and end-systole. Quantifies RV systolic function.
FAC (%) = (RVEDA − RVESA) / RVEDA × 100
Haemodynamics & volume status
IVC · RV pressures · congestionVExUS congestion grading
Grades systemic venous congestion in cardiorenal and post-cardiac-surgery patients. Trigger is a plethoric IVC (>2 cm); then assess hepatic, portal, and intra-renal vein Doppler waveforms for severity.
Grade 0 = no congestion · Grade 1 = mild · Grade 2 = moderate · Grade 3 = severe (high risk of AKI). Educational reference — clinical decisions require integration with the full picture.
IVC collapsibility index
Subxiphoid IVC long-axis · M-mode 2-3 cm from RA junction. Compares max (expiration) and min (inspiration) diameters in spontaneously breathing patients.
CI (%) = (IVCmax − IVCmin) / IVCmax × 100
Right atrial pressure from IVC
ASE-recommended categorical RAP estimate from IVC max diameter and respiratory collapse — for use in RVSP calculation.
RVSP / sPAP
Right ventricular systolic pressure (≈ systolic pulmonary artery pressure in absence of RV outflow obstruction). From CW Doppler across tricuspid regurgitation jet.
RVSP ≈ 4 × (TR Vmax)² + RAP
Low < 36 mmHg · Intermediate 36–50 · Elevated > 50 mmHg.
E/e' ratio
Mitral E wave (PW Doppler at mitral valve in A4C) over septal e' wave (Tissue Doppler at medial mitral annulus). Estimates LV filling pressure when EF is preserved — useful in HFpEF assessment.
E/e' = E (cm/s) ÷ e' (cm/s)
< 8 normal · 8 – 14 indeterminate · > 14 elevated filling pressures.
Stroke volume & cardiac output
From LVOT diameter (PLAX, zoomed) and LVOT VTI (PW Doppler in A5C). Estimates forward flow per beat and per minute. Trends are more useful than absolute values — use serially to gauge fluid responsiveness.
CSA = π × (LVOT/2)² · SV = CSA × VTI · CO = SV × HR
Use serially. A 12–15% rise in VTI after passive leg raise or 250 mL fluid challenge suggests fluid responsiveness.
Normal LVOT VTI in adults: ~ 18 – 22 cm.
Normal cardiac index: 2.5 – 4.0 L/min/m².
Other POCUS calculators
Vascular · Renal · Obstetric · EyeAAA classifier
Outer-wall to outer-wall AP diameter in transverse view at largest diameter.
Bladder volume
Three orthogonal bladder dimensions on suprapubic ultrasound.
V (mL) ≈ L × W × H × 0.52
CRL → gestational age
Crown-Rump Length is the most accurate dating measurement at 6–13⁺⁶ weeks.
GA (weeks) ≈ (CRLmm + 42) / 7
Cardiac activity expected at CRL ≥ 7 mm. FHR normal 110–160 bpm at 6–7 weeks.
Optic nerve sheath diameter
Linear high-frequency probe, transverse axial view, 3 mm posterior to retina, outer-to-outer measurement. NO pressure on the globe.
Adults: ≤5 normal · 5.1–5.5 borderline · >5.5 suggests raised ICP · >6.0 high suspicion. Paeds use age-adjusted (≈ ≤ 4.5–5 mm).
Hydronephrosis grading (SFU)
Society for Fetal Urology system — qualitative grading of pelvicalyceal dilatation on bedside renal ultrasound.
The POCUS mindset.
Six steps. Every scan.
Before any probe touches skin, the operator runs through a 6-step cognitive workflow. Every module, calculator, and case in this hub follows this loop. Skip a step and you skip the question.
Clinical question
Define what you must know right now to act. Without this, every other step is wasted. The probe is a tool to answer a question, not a fishing expedition.
Best probe & view
Match probe and window to the question. Cardiac → phased array. Trauma → curvilinear. Vessels and procedures → linear. Don't choose by habit; choose by the question.
Acquire image
Optimise depth, gain, focus. Use orthogonal planes. Save clips, not just stills. If you can't get the view, document inadequate windows — don't pretend.
Interpret findings
Compare to normal. Look for both positives and negatives. Beware confirmation bias. The eye sees what the brain expects unless you actively disagree with yourself.
Integrate
POCUS finding plus history, vitals, labs, ECG, prior imaging. POCUS never travels alone. A finding is only as useful as its place in the bigger picture.
Action & document
Communicate the safe, informed decision. Document the scan, findings, limitations, and the action they drove. Close the loop with the team.
Scan by syndrome,
not by anatomy.
Four protocols cover most ED resuscitations. Each is a structured cognitive sequence — clinical question → views → pattern → action. Click through to see how each maps from finding to diagnosis.
Five-domain sweep · HIMAP
Mnemonic: HI MAP — when the patient is low MAP, restore them to HI MAP. Heart, IVC, Morrison's, Aorta, Pulmonary.
Combined echo + lung profile
Rapid combined echo and lung ultrasound for acute dyspnoea, chest pain with breathlessness, peri-arrest physiology. Designed to distinguish CHF, COPD/asthma, pneumonia, PE pattern, and tamponade.
The trauma five
Answers four questions in under three minutes: free fluid in abdomen / pelvis / pericardium, and pneumothorax. Negative does not exclude — sensitivity is reduced for retroperitoneal and small-volume bleeds. Repeat when the patient changes.
Reversible cause sweep
Used during the rhythm check pause (≤10 seconds) to identify reversible causes. Performed by a dedicated team member; must not delay compressions or rhythm-check timing. Subxiphoid is the workhorse view; lung is the backup.
One view.
Many protocols.
A subxiphoid view answers questions in eFAST, FELS, RUSH, and Arrest POCUS. Lung zones serve CLUE, RUSH, and eFAST. Master the views once — apply them across every resus syndrome.
| View | Window / target | eFAST | FELS | RUSH | CLUE | Arrest | Focused app |
|---|---|---|---|---|---|---|---|
| SUB-X | Subxiphoid 4-chamber | Echo | |||||
| PLAX | Parasternal long axis | Echo | |||||
| PSAX | Parasternal short axis | Echo | |||||
| A4C | Apical 4-chamber | Echo · TAPSE · EF | |||||
| IVC | Subxiphoid IVC long | Echo · VExUS | |||||
| RUQ | Hepatorenal · Morrison's | eFAST · Renal · GB | |||||
| LUQ | Splenorenal | eFAST · Renal | |||||
| PELVIS | Suprapubic / Pouch of Douglas | eFAST · OB · Renal | |||||
| AORTA | Trans + long axis | AAA | |||||
| LUNG-ANT | Bilateral anterior chest | Lung | |||||
| LUNG-LAT | Lateral / base · effusion | Lung | |||||
| CFV / POP | Compression DVT scan | DVT | |||||
| OCULAR | Trans + sag · ONSD | Ocular · raised ICP | |||||
| TVUS | Endocavity | OB · Gyn · early pregnancy |
The errors that kill scans.
Most POCUS harm comes not from machine skill but from cognitive shortcuts. Each of these traps has a specific corrective rule — recognise the shortcut, apply the rule.
Three phases.
Built for credentialing.
A structured pathway from basic probe handling to advanced integrated resuscitation POCUS. Aligned with ACEM, ACEP, and RNZCUC frameworks. Logbook quotas are educational benchmarks — confirm with your local credentialing body.
Phase 01 · Foundations
Master probe handling, orientation, knobology, image optimisation, normal anatomy, documentation, and infection control. Build the muscle memory before adding complexity.
Phase 02 · Syndrome-based scanning
Every resus patient gets a structured POCUS workflow: clinical question → three views → finding that changes management → backup plan. Move from "what does it look like?" to "what does it mean?"
Phase 03 · Advanced integration
VTI, venous congestion, tamponade physiology, lung profiles, procedural needle guidance, serial reassessment. POCUS as part of a continuous resus loop — not a one-shot snapshot.
The physics behind every image.
A working knowledge of how ultrasound waves travel through tissue is the difference between guessing and reading. These principles determine probe choice, depth setting, and which artefacts are noise versus findings.
Frequency & wavelength
Ultrasound is sound above 20 kHz; diagnostic POCUS uses 2–20 MHz. Higher frequency means shorter wavelength, which gives finer detail but penetrates less. Wavelength = speed of sound ÷ frequency.
Probe frequency vs depth
You cannot have both. Choose probe by depth of target, not familiarity. Linear (7–15 MHz) for superficial structures. Curvilinear (2–5 MHz) for abdomen/lung. Phased array (1–5 MHz) for heart through narrow rib spaces.
Acoustic impedance
Resistance a tissue offers to sound transmission. Z = density × velocity. At any interface where impedance changes, some sound reflects (becomes the image) and some transmits. Big mismatches (air ↔ tissue, bone ↔ tissue) reflect almost everything — which is why air and bone appear bright with shadow behind, and why gel matters.
Attenuation
As the wave travels deeper, energy is lost to absorption (heat), reflection, and scattering. Attenuation increases with depth and with frequency — another reason high-frequency probes can't see deep. Time Gain Compensation (TGC) on the machine compensates for this fade.
Echogenicity scale
How bright a structure appears on ultrasound, relative to its surroundings. The vocabulary every report uses:
Axial vs lateral resolution
Axial resolution (along the beam) is the ability to separate two structures stacked along the beam path; it depends on wavelength and is always the better of the two. Lateral resolution (across the beam) depends on beam width and is best at the focal zone — which is why you adjust focus to the level of interest.
Speed of sound
The machine assumes 1540 m/s in soft tissue to calculate depth from echo return time. When the wave passes through tissue with a different speed (fat ~1450, bone ~4080) the geometry assumption breaks — and that's where many artefacts come from.
Knobology — the dials that change diagnosis.
Most poor scans aren't an anatomy problem; they're an optimisation problem. These are the controls every POCUS user touches in the first 30 seconds of a scan, and the rules of thumb that get an image diagnostic.
How deep to look
Set so the structure of interest fills the lower two-thirds of the screen. Too shallow → cropped target. Too deep → tiny target, wasted resolution.
Overall brightness
Amplifies returning echoes. Set so blood/fluid is black and tissue planes have full grey-scale range. Over-gained = washed out, under-gained = misses subtle pathology.
Time gain compensation
Sliders that adjust gain at specific depths to compensate for attenuation. Top sliders = near field, bottom sliders = far field. Aim for uniform brightness top to bottom.
Focal zone placement
Concentrates the beam at a chosen depth, sharpening lateral resolution at that level. Place the focus marker at the depth of interest — usually mid-image.
Within probe range
Many probes have a frequency toggle (low / mid / high). Higher frequency = better resolution, less penetration. Drop to lower frequency in larger patients or when imaging deep structures.
Tissue harmonic imaging
Uses the second harmonic frequency from tissue to reduce noise and improve contrast in difficult bodies. Often labelled "THI" — turn on for adult abdominal and cardiac scans.
Greyscale contrast
Range of echo intensities displayed. Wide range = soft, smooth image (cardiac). Narrow range = high contrast (procedures, MSK). Most presets handle this — touch only if needed.
Magnify a region
Two flavours: read zoom (magnifies pixels — no extra detail) and write zoom (re-acquires data, true higher resolution). Always prefer write zoom when measuring (e.g. AAA diameter).
Capturing the image
Freeze captures the live image. Cine scrolls back through the previous seconds — invaluable for grabbing the systolic frame or a B-line. Save clips, not just stills, for cardiac and lung.
Pre-tuned settings
The machine's starting point: cardiac, abdominal, OB, MSK, vascular. Each adjusts dynamic range, harmonics, frame rate, and orientation. Always start from the right preset before fiddling.
Probe orientation marker
The notch / dot on the probe corresponds to a marker on the screen. Convention: cardiology has indicator on screen-right, all other applications screen-left. Check before every scan.
B-mode · M-mode · Doppler
B-mode is the 2D greyscale default. M-mode shows one line over time (TAPSE, lung sliding). Colour Doppler shows flow direction. PW/CW Doppler quantifies velocities at a point or peak.
Artefacts — some are noise,
some are findings.
Artefacts arise when the machine's assumptions about how sound travels are violated. Most are noise to ignore. Some — A-lines, B-lines, lung point, comet tail at a needle tip — are diagnostic findings in their own right. Knowing which is which is the difference between confidence and confusion.
Accredited resources.
This hub draws on the following accredited educational programs and references. All clinical content is synthesised for educational purposes — please consult primary sources for clinical decision-making.