HighYield Ultrasound · Trainee Series

The Sonography Trainee Manual

A zero-to-competent curriculum in diagnostic ultrasound for student and newly qualified sonographers, ultrasound technologists and clinicians learning point-of-care scanning. Eight sections take you from picking up a transducer for the first time to producing — and honestly critiquing — diagnostic images, safely. Written the way a good senior teaches at the machine: what to do, why the physics makes it so, and where beginners reliably go wrong.

How to use this page. Work through the tabs in order on your first pass — orientation and knobology before technique, technique before Doppler, everything before you touch a patient list. After that, treat it as a reference: the knobology, image-optimisation and safety tabs are the ones you will reopen every week. Nothing here replaces your local protocols, your professional-body scope of practice, or supervised hands-on training.

Representative teaching values — follow local protocols. Frequencies, index limits, angle conventions and preset numbers on this page are typical teaching figures to build a working mental model. Actual settings depend on your machine, transducer, patient and department. Always defer to your equipment manuals, your professional guidelines (BMUS / AIUM / WFUMB / SDMS and national bodies) and your supervisor’s protocols.

1Machine & Transducers 2Knobology 3Ergonomics & Technique 4Image Optimisation 5Doppler Basics 6Core Protocols 7Documentation 8Safety & Governance

1 · Orientation & the Machine

Ultrasound is the one modality where the operator is the equipment: the image only exists while your hand and eye are creating it, and it can never be re-read from a different angle later. That makes understanding how the image forms — and which transducer builds it — the foundation everything else sits on.

How the image forms — pulse–echo in one paragraph

A transducer contains piezoelectric elements that convert an electrical pulse into a short burst of high-frequency sound (typically 2–15 MHz for general imaging), then listen for the returning echoes. This is the pulse–echo principle.
Sound travels into tissue at an assumed average speed of 1540 m/s. The machine measures the time for an echo to return and, because speed is assumed constant, converts time into depth (range equation). Wrong assumptions about speed are the root of several artifacts (Tab 4/8 thinking).
Echoes arise at acoustic impedance boundaries — interfaces between tissues of differing density/stiffness. A big mismatch (soft tissue↔bone, soft tissue↔gas) reflects almost everything, which is why bone and bowel gas cast shadows and why you cannot image lung parenchyma directly.
Echo amplitude is mapped to brightness — this is B-mode (brightness mode), the grey-scale image you spend most of your day in. Bright = strongly reflective (hyperechoic); dark = weakly reflective or fluid (hypo/anechoic).

Frequency is the master trade-off. Higher frequency = better resolution but shallower penetration; lower frequency = deeper penetration but coarser detail. Every transducer choice and half the knobs on the machine are you negotiating this single compromise. Hold it in your head from day one.

Frequency, resolution and penetration

Axial resolution (ability to separate two structures along the beam) improves with higher frequency / shorter wavelength / shorter pulse. It is generally the best resolution you have.
Lateral resolution (separating structures side-to-side, perpendicular to the beam) improves with higher frequency and with tight beam focusing — hence focal-zone placement matters (Tab 2/4).
Penetration falls as frequency rises because higher-frequency sound is attenuated faster (roughly, attenuation ≈ 0.5 dB/cm/MHz round-trip in soft tissue). A 12 MHz probe gives beautiful detail on a superficial thyroid but will not reach a deep kidney.
Practical rule: use the highest frequency that still reaches your target with adequate signal. If the deep field is noisy/grey, drop frequency (or switch to a lower-frequency probe) before you reach for gain.

Transducer types — pick the tool for the window

Transducer	Footprint & frequency	Field shape	Typical use
Linear array	Flat, wide; high freq ~5–15+ MHz	Rectangular, no divergence	Superficial, high-detail: thyroid, breast, testes, MSK, vessels, DVT, lines/procedures, neonatal.
Curvilinear (convex)	Curved, wide; low freq ~2–5 MHz	Wide fan, diverging	Deep general work: abdomen, obstetrics, renal, bladder, FAST. The default abdominal probe.
Phased array (sector)	Small footprint; low freq ~1–5 MHz	Narrow apex → wide fan	Small acoustic windows between ribs: cardiac (echo), some abdominal/lung. Fits intercostal spaces.
Endocavity	Small, end/side-fire; ~5–10 MHz	Wide fan close to tip	Transvaginal, transrectal — close proximity gives high-frequency detail internally. Requires HLD (Tab 8).

Others you will meet: intraoperative and laparoscopic probes, transoesophageal (TOE/TEE), 3D/4D volume probes, and pencil/CW Doppler probes. All obey the same frequency–penetration trade-off.

Imaging modes you’ll switch between

B-mode (2D): the grey-scale anatomical image — your home base.
M-mode (motion): a single line sampled over time; measures motion/timing (fetal heart rate, cardiac wall, lung sliding).
Colour / power Doppler: flow overlaid on B-mode (Tab 5).
Spectral Doppler (PW/CW): a velocity–time waveform for quantifying flow (Tab 5).
Harmonics / compound / elastography: image-quality and tissue-characterisation modes (Tab 4).

Care of the transducer

Transducers are the most expensive and most fragile part of the system. Never drop, knock or let one hang and swing — a cracked lens or delaminated array is a five-figure repair and can cause artifacts or patient burns.
Clean and disinfect between every patient to the correct level for the exam (low-level for intact-skin external use; high-level for endocavity/broken skin — Tab 8).
Inspect the lens and cable for cracks before use; a damaged probe is both an image-quality and an electrical-safety problem — take it out of service and report it.
Use only manufacturer-approved gels and wipes; some agents degrade the housing or lens.

2 · Knobology

“Knobology” is the working fluency of the control panel — knowing which control changes what, and in which order to reach for them. The single most common beginner error is fixing a signal problem with the wrong knob (turning up gain to brighten a poorly penetrated deep field, when the fix was lower frequency or more output). Learn the order of operations and half your images improve overnight.

The core controls, in the order you should think about them

Control	What it does	Beginner guidance
Preset / exam type	Loads frequency, dynamic range, maps, index limits and defaults for the exam.	Select the correct preset first — it sets sensible starting points and safety limits (e.g. OB presets cap output). Wrong preset = fighting the machine all scan.
Depth	How far into the body the image field extends.	Set so your target fills ~⅔ of the screen with a little tissue beyond it. Too much depth = tiny anatomy and lower frame rate; too little = you clip the far border.
Frequency	Trades resolution against penetration (Tab 1).	Highest that still reaches the target. Many probes offer Res / Gen / Pen sub-bands — start General, shift toward Pen for large patients.
Focus (focal zone)	Position of tightest lateral resolution / narrowest beam.	Place the focal marker at or just below your region of interest. Multiple focal zones sharpen more depth but drop frame rate.
Overall gain	Amplifies all returning echoes (whole image brightness) — a receiver setting, not more energy into the patient.	Set so fluid (bladder, vessels, cysts) reads truly black and solid tissue is mid-grey. Too much gain washes out real detail with noise.
TGC (time-gain compensation)	Depth-dependent gain (the slider bank) — boosts deep echoes to offset attenuation so tissue looks uniform top-to-bottom.	Adjust the sliders to make an evenly reflective organ look the same brightness at every depth. A “staircase” TGC pattern is the classic beginner tell.
Output power (acoustic)	Energy actually transmitted into the patient — drives TI/MI (Tab 8).	This is the one control that raises patient exposure. Under ALARA, prefer raising receiver gain first; only raise output when gain alone can’t recover signal.
Dynamic range	Range of echo amplitudes mapped to the grey-scale.	Wide DR = smooth, many greys (soft, good for parenchyma); narrow DR = high contrast, fewer greys (punchy, good for stones/borders). Presets usually set this well.
Freeze / Cine	Stops live scanning; cine scrolls back through the last stored frames.	Freeze, then cine back to the best frame before measuring or saving — you rarely capture the ideal frame live.
Callipers / measure	Places measurement crosshairs on the frozen image.	Measure only on a frozen, optimised frame at true perpendicular/plane. Sloppy calliper placement is a top reporting error (Tab 7).

Gain vs output — the distinction that matters most

Gain amplifies echoes after they return. It changes how bright the image looks; it does not change patient exposure. It costs you noise if overdone.
Output power increases the acoustic energy sent into the patient. It genuinely improves deep signal-to-noise — but it raises TI/MI (Tab 8).
Under ALARA, the reflex is: optimise depth/frequency/focus → adjust gain and TGC → only then raise output. Especially in obstetric and neonatal scanning, keep output as low as gives a diagnostic image.

Frame rate — the hidden budget

Frame rate (temporal resolution) is spent on: depth, sector width, number of focal zones, line density, and colour box size.
A laggy image blurs moving structures (heart, fetus, vessels). If frame rate is poor: narrow the sector, reduce depth, reduce focal zones, or shrink the colour box.
There is a permanent three-way tension between resolution, penetration and frame rate — you can favour two, never maximise all three. Choose deliberately for the clinical question.

The five-second optimisation loop, every image: right preset → depth → frequency → focus on the target → gain/TGC even top-to-bottom → freeze → cine to the best frame → measure. Say it under your breath until it’s automatic.

3 · Ergonomics & Scanning Technique

Sonography has one of the highest rates of work-related musculoskeletal injury of any clinical profession. The habits you build in your first month decide whether you scan pain-free for a career or develop shoulder, wrist and neck injuries within a few years. Ergonomics is not optional comfort — it is occupational health, and it is examinable in most training frameworks.

Posture & positioning — protect your body

Keep the patient close and the work in front of you. Reaching across a couch is the number-one cause of shoulder injury. Move the patient toward you, or move yourself and the machine, so your scanning arm stays close to your body.
Abduct the scanning shoulder <30°. The higher your elbow lifts away from your side, the greater the static shoulder load. Lower the couch, raise your chair, roll the patient toward you.
Neutral wrist. Grip the transducer so the wrist is straight, not cocked back or bent — repeated extreme wrist angles cause tendinopathy and carpal tunnel symptoms.
Support your scanning arm on the couch, the patient, or a rolled towel where possible, so muscles aren’t holding it in mid-air.
Screen and console at eye level and within reach so you’re not twisting your neck or trunk to see and adjust. Adjust the bed/chair/monitor for every patient — thirty seconds now saves years.
Take micro-breaks and vary grip. Long lists without breaks are where injuries accumulate.

Probe grip & coupling

Grip lightly, near the footprint. A relaxed pen-like or cradle grip with fingers close to the skin gives control with the least muscle effort. A tense, high grip fatigues fast and reduces fine control.
Anchor a finger on the patient for stability and to modulate pressure — the hand rests, the wrist doesn’t float.
Coupling gel excludes air (which otherwise reflects ~100% of the beam and blocks all imaging). Use enough warm gel; a dry or air-gapped contact gives a black, useless image. Warmed gel improves patient comfort and cooperation.
Pressure is a tool, not a default. Enough to couple and to displace bowel gas (graded compression); too much causes patient discomfort and distorts anatomy and Doppler. Ease off over tender areas and superficial vessels.

Orientation convention — never scan disoriented

Each transducer has a notch/ridge/marker corresponding to a marker (dot) on one side of the screen.
Standard convention: the probe marker points to the patient’s right in transverse and toward the patient’s head in sagittal/longitudinal, with the screen marker top-left — so anatomy left-of-screen corresponds to that reference side. (Echocardiography uses its own conventions — learn them separately.)
Prove it before you scan: tap or wiggle one edge of the probe and confirm which side of the image moves. Getting left/right wrong is a genuine patient-safety error (wrong-side reporting).
Always label the region and side/plane on saved images (Tab 7).

The four probe movements — the whole craft of scanning

Every acquisition is a combination of just four hand movements. Naming them makes your scanning deliberate rather than a hopeful wobble:

Movement	What you do	What it achieves
Slide (translate)	Move the whole probe across the skin, keeping the angle.	Survey/sweep through an organ; follow a structure along its length.
Rotate	Spin the probe about its own axis.	Move between transverse and longitudinal planes; align the long axis of a vessel or duct.
Rock (heel–toe)	Tilt within the scan plane, angling the beam along its length.	Bring a structure to the centre of the field; steer under a rib.
Fan (tilt/sweep out of plane)	Tilt side-to-side across the scan plane.	Sweep through the full thickness of an organ so nothing is missed between planes.

Fan through everything. A single static image proves nothing — pathology hides between planes. Sweep the full width and length of every organ, watching live, before you freeze the representative images. “Scan the whole thing, then document parts of it.”

Patient preparation & positioning basics

Explain and gain cooperation — a comfortable, informed patient holds still and breath-holds on cue. Maintain dignity and appropriate chaperoning, especially for intimate examinations.
Preparation matters: fasting for gallbladder/upper abdomen (fatty meal empties the gallbladder and fills the duodenum with gas), full bladder for pelvic/lower-abdominal transabdominal work (acoustic window), empty bladder before transvaginal.
Use the acoustic window: position the patient (decubitus, oblique, erect), use breath-holds, and use adjacent fluid-filled organs (full bladder, liver as a window to the right kidney) to see past gas and bone.

4 · Image Optimisation

Once the basics are set (Tab 2), a second layer of software tools lifts a merely-adequate image into a diagnostic one. These are the controls that separate a scan the reporter trusts from one they ask you to repeat. Understand what each does — because each also has a cost, usually in frame rate or in introducing its own artifact.

Tissue harmonic imaging (THI)

Transmits at one frequency but forms the image from the harmonic (≈2×) frequencies generated within tissue as the beam propagates.
Benefits: reduced reverberation, side-lobe and clutter artifact, cleaner cystic/fluid spaces, better contrast — especially valuable in large or difficult-to-image patients.
Cost: harmonic signal is weaker, so penetration can drop. Turn it off if the deep field goes too noisy.
Practical: THI is on by default in most abdominal presets; it is the single most useful “clean up the image” toggle you have.

Spatial compound imaging

Steers the beam through several angles and averages the frames into one.
Benefits: suppresses speckle, clutter and noise, reinforces real interfaces, and improves visualisation of curved borders and structures behind refractive shadows.
Cost: reduced frame rate; can soften or lose posterior acoustic shadowing and enhancement — the very artifacts you sometimes rely on (a shadowing gallstone, enhancement behind a cyst). Toggle it off when you need those signs.

Focal zone placement

The beam is narrowest — and lateral resolution best — at the focal zone. Place the focal marker at (or just deep to) your region of interest.
Adding focal zones sharpens a greater depth but lowers frame rate proportionally — a poor trade for moving structures.
A focus left parked too shallow or too deep is a common cause of a soft, unconvincing image at the level that actually matters.

Speckle reduction (SRI-type)

Adaptive filtering that smooths the grainy speckle texture inherent to ultrasound while trying to preserve true edges.
Benefit: cleaner, more “photographic” parenchyma; easier borders.
Cost: at high strength it can blur genuine fine detail and small structures — use moderate levels and know what your default is.

Sector width, line density & frame rate

Narrowing the sector concentrates the same scan lines into a smaller field: higher line density (better lateral resolution) and higher frame rate. Widen only when you need the overview.
Coded excitation transmits longer, encoded pulses and decodes the echoes — improving penetration and signal-to-noise without sacrificing the axial resolution a longer pulse would normally cost. It’s why modern machines reach deeper cleanly.
Write zoom vs read zoom: “write” (acquisition) zoom re-scans the region at full line density — genuinely more detail; “read” (display) zoom just magnifies stored pixels — no new information. Use write zoom for small structures.

The optimisation artifacts to recognise (and use)

Artifact	Appearance	Meaning / use
Acoustic shadowing	Dark band deep to a strong reflector/absorber	Stones, gas, bone. A diagnostic sign — don’t compound it away when hunting a gallstone.
Posterior enhancement	Bright band deep to fluid	Confirms a cyst/fluid-filled structure vs a solid one.
Reverberation / comet-tail / ring-down	Repeating parallel lines or tapering tail	Between two strong reflectors (needle, gas, metal). THI reduces the nuisance kind; comet-tail can be a useful sign (e.g. B-lines in lung).
Mirror image	Duplicate structure across a strong reflector (diaphragm)	Recognise it as artifact, not a second lesion.
Edge shadowing / refraction	Thin shadow at the edge of a curved structure	Beam bending at a curved interface — not pathology.
Anisotropy (MSK)	Tendon looks dark when the beam isn’t perpendicular	Keep the beam perpendicular to tendons/nerves; angling creates false hypoechoic “lesions”.

Optimisation cuts both ways. THI, compounding and speckle reduction all suppress artifacts — but several artifacts are diagnostic signs. Know which mode is on, and be willing to turn a feature off to reveal shadowing or enhancement.

Pro

Advanced imaging & artifact atlas

Go deeper: contrast-enhanced ultrasound (CEUS), shear-wave and strain elastography, panoramic and 3D/4D acquisition, and a fully worked visual atlas of every artifact — what causes it, how to recognise it, and when it’s a sign rather than a nuisance.

Preset-by-preset optimisation recipes for abdomen, small parts, vascular, obstetrics and MSK
Elastography acquisition technique and pitfalls (breath-hold, pre-load, ROI placement)
Side-by-side artifact image bank with “sign vs artifact” decision prompts

Unlock with HighYield Pro →

5 · Doppler Basics

Doppler adds flow — direction, presence and velocity — to the grey-scale anatomy. It is where beginners most often produce confident-looking but wrong numbers, because Doppler is exquisitely dependent on the angle between the beam and the flow. Master the geometry first; the buttons follow.

The Doppler principle & the angle

Moving blood shifts the frequency of the returning echo (the Doppler shift): flow toward the probe raises frequency, flow away lowers it. The measured velocity depends on the cosine of the angle between the beam and the flow.
Because velocity ∝ 1/cos θ: at 0° (beam parallel to flow) the shift is maximal and most accurate; at 90° cos θ = 0, so there is no measurable shift — flow can be present yet invisible.
Keep the Doppler angle ≤ 60° for velocity measurement, and use angle correction aligned to the vessel wall. Beyond 60°, small angle errors cause large velocity errors — the classic teaching threshold — and intrinsic spectral broadening further inflates peak velocities.
Angle correction: set the cursor parallel to the vessel walls. Steer the beam, heel-toe the probe, or choose a different window to get a favourable angle — don’t just crank the correction cursor to “fix” a bad geometry.

The 60° rule in one line: for any velocity you’ll report (e.g. carotid stenosis criteria), keep the insonation angle at or below 60° and the angle cursor parallel to flow. A steep angle or misaligned cursor produces velocities that are simply wrong — and stenosis grading lives and dies on those numbers.

Colour Doppler

Encodes mean flow direction and velocity as colour over a region (the colour box). Convention (BART): Blue Away, Red Toward — but confirm the colour bar, it can be inverted.
Colour box: keep it small and over the area of interest — a big box tanks frame rate and sensitivity.
Steer the colour box on a linear probe to improve the angle to flow (the box can be angled even when the B-mode isn’t).
Still angle-dependent: a vessel at 90° to the beam may show little/no colour despite good flow — angle the box or the probe.

Power Doppler

Encodes the amplitude (strength) of the Doppler signal, not velocity/direction.
More sensitive to slow/low-volume flow and less angle-dependent — good for parenchymal perfusion, small vessels, testis/ovary flow, and confirming “is there any flow at all?”
Trade-off: no direction, no velocity, and more susceptible to motion (flash) artifact.

Spectral Doppler — PW and CW

	Pulsed-wave (PW)	Continuous-wave (CW)
How	Samples one small gate at a chosen depth (range resolution).	Transmits & receives continuously along a line — no range resolution.
Strength	Tells you flow at a specific point.	Measures very high velocities without aliasing.
Limit	Aliases above the Nyquist limit (½ the PRF) — high velocities wrap around.	Cannot say where along the beam the velocity came from (range ambiguity).
Use	Vessel/organ waveforms, RI/PI, portal/hepatic flow.	High-velocity jets (valvular, tight stenoses) in echo/vascular.

PRF / scale, wall filter & baseline

PRF (scale): the velocity range displayed. Set it to the flow you’re measuring — too low aliases; too high loses slow flow. Raise scale for high-velocity arteries, lower it for slow venous/parenchymal flow.
Wall (high-pass) filter: removes low-frequency noise from vessel-wall motion. Set too high, it erases genuine slow diastolic/venous flow (false “no flow”); set as low as noise allows for low-velocity studies.
Baseline: shift it to fit the waveform on screen and to give more Nyquist headroom in the dominant flow direction before re-aliasing.
Doppler gain: enough to fill the waveform without a background spray of noise.

Aliasing — recognise and fix it

What it is: the Doppler shift exceeds the Nyquist limit (½ PRF), so high velocities “wrap” — colour shows an abrupt colour-swap through the middle (not at the wall); spectral traces wrap top-to-bottom.
Fixes, in order: raise the PRF/scale → shift the baseline → reduce depth → use a lower transmit frequency → in extremis switch to CW (spectral).
Don’t confuse aliasing (a fixable setting artifact) with true turbulence/high-velocity jet (a finding) — though aliasing at a stenosis is itself a useful pointer to where to interrogate with PW/CW.

Doppler is more energetic — mind the indices. Spectral and colour Doppler deposit more energy than B-mode, raising TI in particular. Be especially disciplined with Doppler in obstetric and neonatal scanning: keep TI low, dwell briefly, and follow the fetal-Doppler guidance in Tab 8.

6 · Core Protocols — Your First Scans

These are high-level orientations, not full protocols — enough to know the probe, window, sweep and the images you’re aiming to capture. Every one must be performed under supervision and to your department’s full protocol and competency requirements before you scan unsupervised. The aim here is to give shape to your first attempts.

Scope of practice. These walkthroughs are educational orientation only. Interpretation, measurements against diagnostic criteria, and unsupervised scanning must follow your professional scope, local protocols and supervised sign-off. Do not act clinically on a scan you are not competent and credentialed to perform.

Upper-abdominal survey (curvilinear ~2–5 MHz)

Prep & preset: patient fasted where required; select abdominal preset; supine to start, ready to roll into decubitus. Warm gel.
Liver & right kidney: subcostal and intercostal windows; sweep the whole liver in two planes, use the liver as a window to the right kidney; suspended inspiration drops the liver down for you.
Gallbladder & biliary: long and short axis; look for stones (shadowing), wall, and duct calibre. Turn compounding off if you need clean stone shadowing.
Pancreas & great vessels: transverse epigastric, using the left lobe of liver and a fluid-filled stomach as windows; identify aorta and IVC.
Spleen & left kidney: left coronal/intercostal, patient in right decubitus; the spleen is a window to the left kidney.
Document representative labelled images of each organ in two planes; sweep live through everything before freezing (Tab 3).

Bladder & simple pelvic (curvilinear)

Best with a full bladder (acoustic window and distends the target).
Suprapubic, angle caudally; sweep transverse and sagittal through the full bladder.
Assess wall, contents/debris, and — a common first task — bladder volume (length × width × height × 0.52, the prolate-ellipsoid formula) and post-void residual.
In females, the uterus sits behind the bladder; note the retrovesical anatomy but leave detailed gynae to protocol/TV imaging.

Thyroid (linear, high frequency ~7.5–15 MHz)

Patient supine, neck extended over a pillow/roll. Copious gel; light pressure.
Systematic sweep of both lobes and isthmus in transverse and longitudinal; measure each lobe in three dimensions.
Characterise any nodule (composition, echogenicity, shape, margin, calcification) against your department’s reporting system.
Keep the beam perpendicular; extend laterally to check for lymph nodes.

DVT — lower-limb compression (linear, ~5–9 MHz)

Principle: a normal vein fully collapses under gentle probe pressure; a vein containing thrombus does not. Compression is the core of the test.
Transverse plane, probe perpendicular; identify the vein next to its artery (the vein is the compressible one).
Compress at intervals down the leg per your protocol (e.g. common femoral through popliteal in a 2-point/3-point study, or full-length per local policy), watching the vein flatten completely.
Augment with colour/spectral as protocol requires (phasicity, augmentation), but compression is king.
Document the compressed/uncompressed pairs at each level. Incomplete or non-compression is the abnormal finding to escalate.

FAST — the four windows (phased/curvilinear, low freq)

Focused Assessment with Sonography in Trauma looks for free fluid. Four windows, each a place fluid collects:

Window	Where	Fluid collects at
RUQ (Morison’s)	Right flank — hepatorenal recess	Between liver & right kidney; also right paracolic gutter, subphrenic.
LUQ	Left flank — splenorenal	Perisplenic / subphrenic (often the earliest); around the left kidney.
Pelvis	Suprapubic, both planes	Rectovesical (male) / pouch of Douglas (female) — most dependent point.
Pericardial/subxiphoid	Subcostal, angled to the heart	Pericardial effusion around the heart.

eFAST adds anterior chest views for pneumothorax (loss of lung sliding / lung point). FAST is a rule-in tool for free fluid — a negative scan does not exclude injury. Always within your resuscitation team’s protocol.

7 · Documentation & Measurement

In ultrasound the images you save and the measurements you make are the permanent record — the reporter (and any future clinician) sees only what you captured, not the live scan in your head. Sloppy labelling and careless callipers turn a good scan into an unusable one. Documentation is a core competency, not an afterthought.

Labelling & standard images

Every stored image needs: correct patient demographics (verified against the request — right patient, right side), the structure imaged, the plane (transverse/longitudinal/sagittal), and the side (right/left) where relevant.
Capture the standard image set for the exam: representative images of each organ in two orthogonal planes, plus any pathology in two planes with and without measurement.
Document pertinent negatives too — an image showing a normal appendix or no free fluid is evidence, not wasted frames.
Get the orientation right on the stored image (Tab 3): a mislabelled left/right is a genuine safety event, not a cosmetic error.
Note technical limitations honestly (body habitus, bowel gas, non-fasted, patient unable to breath-hold) so the report reflects the true confidence of the study.

Calliper technique

Freeze and cine to the best frame first — measure on an optimised, correctly-planed frame, never live.
Measure in the correct plane and at the true maximum (e.g. a vessel diameter perpendicular to its long axis, an organ length in its true long axis) — off-axis measurements read falsely small or large.
Know your convention: leading-edge-to-leading-edge vs inner-to-inner vs outer-to-outer differs by structure and guideline (e.g. IMT, aortic diameter, fetal biometry each have rules). Use the standard for that measurement.
Place crosshairs on a magnified (write-zoom) image for small structures — a one-pixel slip matters more the smaller the target.
Repeatability: measure consistently the same way every time so your numbers are comparable across studies and operators.

Common volume & measurement formulae

Ellipsoid volume: L × W × H × 0.52 — bladder, prostate, thyroid lobe, ovary, etc. (0.52 ≈ π/6).
Bladder residual: ellipsoid volume post-void; report both pre- and post-void.
Doppler indices: Resistive Index RI = (PSV − EDV)/PSV; Pulsatility Index PI = (PSV − EDV)/mean velocity. Measure on a clean, angle-corrected spectral trace (Tab 5).
Always measure against the correct reference range / diagnostic criteria for the exam and machine — a number without its criterion is meaningless.

Reporting basics (know your scope)

Whether a sonographer issues the report or provides a worksheet to a radiologist/clinician varies by country and setting — know your local scope of practice and never exceed it.
A good record describes what was seen (findings, measurements, comparisons) and the technical quality/limitations, and — within scope — an impression. Separate observation from interpretation.
Communicate urgent/unexpected findings immediately per protocol — a documented image in a queue is not communication.
Store images and reports so they are retrievable and comparable (PACS, consistent labelling) — future studies depend on being able to compare with yours.

8 · Safety & Governance Quick Reference

Ultrasound uses no ionising radiation and is very safe — but it is not without bioeffects, and its infection-control demands are real and often underestimated. Two ideas govern practice: keep acoustic exposure ALARA, and keep the transducer clean to the correct level for the exam.

Bioeffects, TI and MI

Two potential mechanisms of harm: thermal (tissue heating) and mechanical (cavitation and radiation force).
Thermal Index (TI): an on-screen estimate of potential heating; it is time-linked — longer dwell means more heating. Variants: TIS (soft tissue), TIB (bone at focus, e.g. later-pregnancy fetal bone), TIC (bone near the surface, e.g. transcranial).
Mechanical Index (MI): an estimate of potential non-thermal (cavitation) effects; it is not time-linked.
Regulatory ceilings: diagnostic systems are generally limited to MI ≤ 1.9 (and TI display up to ~6), but in routine soft-tissue B-mode TI usually stays <1 and MI well below the max. Contrast (CEUS) work uses low MI (often <0.3) to avoid destroying microbubbles.
ALARA in practice: lowest output and shortest exposure that answers the question — set output low, prefer receiver gain, keep the on-screen TI/MI in view, and limit dwell on any one spot.

Obstetric & neonatal caution. The embryo/fetus and neonatal brain/eye are the most sensitive targets. Keep TI (especially TIB in later pregnancy) and dwell time low, use B-mode where possible, and be particularly sparing with spectral/colour Doppler in early pregnancy. Follow BMUS/WFUMB fetal-safety guidance and the “keep it short, keep output low” principle.

Cleaning & disinfection — matched to risk (Spaulding logic)

Contact type	Risk level	Reprocessing
Probe on intact skin (most external scans)	Low (non-critical)	Clean off gel, then low-level disinfection (approved wipe) between patients.
Endocavity (transvaginal, transrectal, TOE)	Semi-critical (mucous membranes)	Cover + clean, then high-level disinfection (HLD) before reuse — every time.
Contact with broken skin, blood, sterile field (e.g. intra-operative, some procedures)	Critical	Sterile sheath + HLD/sterilisation per policy; sterile gel.

Probe covers are not a substitute for HLD: sheaths perforate at a meaningful rate, so endocavity probes need HLD even when a cover was used.
Clean and dry before disinfecting — residual gel and moisture dilute/deactivate high-level disinfectants.
Use only single-use or sterile gel where appropriate; multi-use gel bottles have caused outbreaks — never top up, and follow local gel-handling policy.
Standard precautions always: hand hygiene, gloves for endocavity/procedures, clean the machine, keyboard and couch between patients.

Electrical & equipment safety

Inspect probe lens and cable for cracks before use — damage is an image and electrical-safety fault; withdraw and report.
Don’t overheat: a probe left transmitting on a phantom or resting face-down can self-heat. Freeze when not actively scanning.
Report faults and log them; participate in planned maintenance and QA (phantom checks) per department policy.

Governance & professionalism

Scope of practice: work within your competencies and credentials; escalate beyond them.
Consent, dignity, chaperones — especially for intimate (TV/TR) examinations; explain and document.
Incidental & unexpected findings: follow the local pathway for communicating and safety-netting.
Audit & CPD: reject/repeat awareness, image-quality audit, and continuing professional development are part of safe practice, not extras.

Pro

Competency & safety workbook

The printable companion to this manual: per-exam competency checklists with supervisor sign-off, an ergonomics self-assessment, a probe-reprocessing audit template, and a TI/MI + ALARA quick card mapped to BMUS, AIUM and SDMS frameworks.

Per-exam checklists (abdomen, small parts, vascular, obstetric, POCUS) with pass criteria
Ergonomics & MSK-injury-prevention self-audit
Reprocessing & infection-control audit sheets and printable safety cards