Lung ultrasound is an exam of artifacts. Air scatters the beam, so normal lung is not imaged directly — it is inferred from the pleural line and the patterns behind it. Learning this exam means learning what each artifact says about the ratio of air to fluid beneath the pleura.
It outperforms supine chest radiography for pneumothorax, effusion, and interstitial fluid, and it is fast enough to repeat after every intervention.
Curated from the POCUS 101 Lung Ultrasound Made Easy: Step-By-Step Guide. The clips of lung sliding, B-lines, and the lung point are the core of the exam — view them there.
Linear for the pleural line and pneumothorax; curvilinear or phased array for B-lines, effusion, and consolidation at depth.
Indicator cephalad, spanning two ribs. The "bat sign" — rib, pleural line, rib — confirms you are on the pleura before any interpretation.
At minimum: anterior-superior, anterolateral, and posterolateral (the PLAPS point) on each hemithorax. More zones increase sensitivity.
Bat sign · watch the pleural line shimmer with respiration
Lung sliding is the to-and-fro shimmer of the visceral against the parietal pleura. Its presence at a given spot excludes pneumothorax at that spot.
A-lines vs. B-lines in each zone
Anterior chest in the supine patient · search for the lung point
Air rises: in a supine patient, pneumothorax collects anteriorly. Absent sliding with A-lines raises suspicion; the lung point — the boundary where sliding lung intermittently re-enters the field — is essentially 100% specific and confirms the diagnosis.
Posterolateral, above the diaphragm · effusion and consolidation live here
Pleural effusion appears as an anechoic space between the diaphragm and lung, often with the compressed lung flapping within it. The spine sign — the vertebral bodies visible above the diaphragm — indicates fluid where aerated lung should be.
Consolidated lung appears tissue-like ("hepatization") with hyperechoic air bronchograms; dynamic (moving) bronchograms favor pneumonia over atelectasis.
| Pattern | Components | Suggests |
|---|---|---|
| Normal / dry | Lung sliding + A-lines, <3 B-lines per field | Normal aeration; in dyspnea, consider airway disease or PE |
| Diffuse wet | Bilateral B-lines, often with smooth pleura | Cardiogenic pulmonary edema (correlate with echo and IVC) |
| Focal wet / hepatized | Focal B-lines, subpleural consolidation, dynamic air bronchograms, irregular pleura | Pneumonia |
| Pneumothorax | No sliding + A-lines + no B-lines; lung point confirms | Pneumothorax at the interrogated site |
| Effusion | Anechoic space above the diaphragm, spine sign, flapping lung | Pleural effusion; ultrasound marks the safe tap site |
Lung sliding excludes pneumothorax only where the probe sits. A localized pneumothorax elsewhere is untouched by that finding — scan multiple zones before generalizing.
Right mainstem intubation is the classic mimic: absent sliding on the left with no pneumothorax present. Check tube depth before reaching for a chest tube.
Cardiac pulsation transmitted through non-sliding lung (the "lung pulse") means the pleural surfaces are in contact — effectively excluding pneumothorax at that site even without sliding.
Edema, pneumonia, ARDS, fibrosis, and contusion all produce B-lines. Distribution (diffuse vs. focal), pleural character (smooth vs. irregular), and the clinical picture make the call.
Below the diaphragm is not effusion. Identify the diaphragm and spine explicitly before calling basal fluid, especially on the left where the stomach sits close.
The exam is fast and radiation-free. Rescan after diuresis, after the chest tube, after intubation — the trend is often more informative than the first image.
A starting template for the POCUS note. Text in brackets [ ] and pick-lists in { } are fields to complete. Save it as a SmartPhrase, then edit every field to match the actual study.
POINT-OF-CARE ULTRASOUND: LUNG / THORACIC
Indication: {dyspnea : hypoxia : ? pneumothorax : ? effusion} [***]
Exam type: Focused / limited, multi-zone
Operator: @ME@ Interpretation: independent, real-time
Probe: {linear : phased array : curvilinear}
FINDINGS (by zone, R / L)
- Lung sliding: {present bilaterally : absent [zone / side ***]}
- A-lines vs B-lines: {A-line predominant : focal B-lines [***] :
diffuse bilateral B-lines}
- Lung point: {not seen : seen [side ***] - confirms pneumothorax}
- Pleural effusion: {none : present [side ***], spine sign}
- Consolidation: {none : present [***], air bronchograms}
IMAGE QUALITY: adequate / limited by [***]
Images saved and archived to [PACS / Qpath / ***].
IMPRESSION: [***].
I personally performed and interpreted this study.
Electronically signed: @ME@ @TD@ @NOW@
Sample template only — not a validated institutional SmartPhrase. Verify wording, image-archival, and attestation requirements against your department's POCUS credentialing, coding, and compliance policies before clinical use. Documentation supports, but does not replace, the medical record and QA workflow.