POCUS Tips › Setup
Before You ScanSETUP
Sixty seconds of setup buys you a diagnostic image. Probe, preset, depth, gain — in that order, every time.
Open the interactive view with the loop and quiz →The sixty-second setup
- Pick the probe for the depth you need, then select the matching preset — the preset changes the frame rate and the orientation convention.
- Confirm orientation before you interpret anything: tap the marker side of the probe and watch which edge of the screen brightens.
- Set depth so the structure of interest fills the lower two-thirds, then set gain so fluid is black and tissue is gray.
- Freeze, scroll back through the cine loop, and measure on the best frame — never on the live image.
Probe selection
| Probe | Frequency | Reach for it when |
|---|---|---|
| Phased arraysmall footprint, wide sector | 1–5 MHz | heart, IVC, and lung when you need depth — fits between ribs |
| Curvilinearlarge footprint, wide field | 2–5 MHz | abdomen, pleural effusion, deep structures in larger patients |
| Linearflat footprint, high resolution | 5–15 MHz | pleural line, vessels, soft tissue, procedures |
| Preset matterscardiac vs abdominal | orientation flips | cardiac puts the marker on screen right; abdominal puts it on screen left |
Don’t be fooled — pitfalls
- Interpreting before confirming orientationLeft and right reverse between presets. One finger tap on the probe marker tells you which screen edge is which — do it every time you change probe or preset.
- Too much depthThe commonest reason a bedside image looks unreadable. Shrink depth until the target fills the screen.
- Gain used as a fix for a bad windowGain makes noise brighter, not anatomy clearer. Reposition the patient first.
- Measuring on a live imageFreeze and scroll. Cardiac measurements are phase-specific and cannot be trusted mid-motion.
- Scanning without a questionPOCUS answers a specific yes/no. Decide the question before the gel goes on, and document what you asked and what you saw.
Bad image? Fix it
- Dark, grainy image in a large patientLower the frequency, switch to curvilinear or phased array, and increase output before touching gain.
- Bright near field, dark far fieldAdjust TGC — pull near-field gain down and far-field gain up rather than moving overall gain.
- Ribs everywhereRotate to run along the intercostal space, or move one space up or down. Reposition the patient before you fight the anatomy.
- Patient cannot cooperateTake short clips through several cycles and review them frozen; a five-second clip beats a perfect live image you cannot hold.
- Not enough contactMore gel, firmer even pressure, and check the probe is flush — air under an edge kills a third of the image.
So what — what the finding changes
- The image will not become diagnosticSay so. A documented inadequate study is a legitimate result; an over-read bad image is not.
- The finding will change managementConfirm it in a second view or a second modality before acting on it.
- Between patientsClean the probe per local policy, wipe the cable, and use a cover for anything near a wound or mucosa.
Keep going
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.