Article

Chest ultrasound and pleural assessment

Chest ultrasound: pleural effusion, lung sliding, A and B lines, consolidation and pneumothorax — technique, sonographic signs and limitations.

What it is and when to indicate it

Chest ultrasound assesses the pleura and the superficial lung, being very useful in dyspnea, suspected pleural effusion, chest pain and as guidance for thoracentesis. It is fast, at the bedside and without radiation.

This page organizes the signs in clear language and does not replace the original guidelines (lung ultrasound protocols, AIUM, CBR), supervised training or clinical correlation.

Technique

• Curved or linear transducer; sector for intercostal windows
• Systematically assess the anterior, lateral and posterior fields, comparing sides
• Identify the pleural line between two ribs (bat sign)
• Observe lung sliding, A lines and B lines
• A seated patient facilitates assessment of effusion at the bases

Normal signs and artifacts

• Lung sliding present: movement of the visceral pleura over the parietal pleura
• A lines: horizontal reverberations, the pattern of normal aerated lung
• Seashore sign on M-mode with sliding present
• A few isolated B lines can be normal at the bases
• Lung pulse and respiratory movement of the pleural line

Pathological findings

• Pleural effusion: anechoic space between the pleurae, with a floating atelectatic lung; estimate volume and guide puncture
• Interstitial syndrome: multiple B lines (three or more per field), diffuse in congestion
• Consolidation: hepatized lung with dynamic air bronchograms
• Pneumothorax: absent lung sliding, absent B lines, lung point; stratosphere sign on M-mode
• Pleural thickening, nodules and septations in complex effusion

Pneumothorax: the logic of the signs

No single sign confirms the diagnosis; combine them and correlate with the clinical picture.

• Lung sliding present practically excludes pneumothorax at that point
• Absent sliding is suggestive but nonspecific (pleural adhesion, apnea, selective intubation)
• Absent B lines reinforce the suspicion
• The lung point is specific for pneumothorax when found
• Correlate with the clinical picture and, when needed, radiograph/CT

Normal report template

• Lung sliding present and symmetric in the assessed fields
• A-line pattern, without pathological B lines
• No pleural effusion or consolidation
• No signs of pneumothorax at the examined points
• Regular pleural line, without thickening or nodules

Limitations and pitfalls

• Assessment limited to the pleura and superficial lung; central aerated lesions are not seen
• Subcutaneous emphysema preventing the assessment
• Mistaking physiological B lines at the bases for interstitial syndrome
• Absent sliding due to causes unrelated to pneumothorax
• Report the limitations and the focal nature of the exam

Do not overdiagnose

Combine signs (sliding, A/B lines, effusion, lung point) and correlate with the clinical picture. Lung ultrasound is powerful at the bedside, but doubtful cases go to radiograph/CT. The conclusion should be proportional to the findings.

Sources

Educational content; it does not replace original guidelines, medical evaluation or supervised training. Main references:

• International evidence-based recommendations for point-of-care lung ultrasound (didactic support).
• AIUM. Practice Parameter for the Performance of Thoracic/Lung Ultrasound (when applicable).
• Brazilian College of Radiology (CBR). Standardization and technical guidelines for ultrasound.
• Rumack CM, Levine D. Diagnostic Ultrasound (chest and pleura).
• Radiopaedia. Lung and pleural ultrasound (didactic support, not copied).

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