Focused Question: Is There Fluid or Blood Present in the Pleural Space?
Lung ultrasound can effectively identify or exclude pleural effusion at the bedside. Key signs to evaluate include the presence of the “spine sign,” visible fluid, and the “lung curtain.” These findings help confirm or rule out pleural fluid collection.
Confirming Pleural Effusion:
- Presence of the “spine sign,” where the spine is visible above the diaphragm.
- Visible anechoic (black) fluid collection in the pleural space.
- Absence of the “lung curtain” sign.
Ruling Out Pleural Effusion:
- Presence of the “lung curtain,” where lung tissue obscures the spine above the diaphragm.
- No visible black border above the diaphragm indicating fluid.
- Absence of the “spine sign.”
Ensure proper patient positioning during ultrasound to optimize the evaluation of these signs.
The clips below will demonstrate these ultrasound findings in various cases, aiding in the recognition and assessment of pleural effusion.
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Ultrasound clip showing pleural effusion in the left pleural cavity. The diaphragm is clearly visible in the middle, with free fluid above it on the left. No curtain sign is present, and the spine sign is visible, with vertebrae seen above the diaphragm. Compressed lung tissue is also seen in the fluid. The spleen is visible below the diaphragm during expiration.
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This ultrasound clip demonstrates the “curtain sign.” At the top of the clip, the aerated lung expands downward into the costophrenic recess during inspiration, causing the lung tissue to obscure the ultrasound beam. As a result, the underlying tissues below the diaphragm momentarily disappear from view. During expiration, the lung retracts, moving away from the costophrenic recess, and the underlying tissues become visible again.
The “curtain sign” is an important artifact indicating the absence of pleural effusion. Its presence confirms that the lung can move freely into the costophrenic recess without fluid restricting its movement. When pleural effusion is present, fluid occupies this space, preventing the lung from reaching the recess and thus eliminating the curtain sign.
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Two ultrasound clips comparing normal findings and findings with pleural effusion on the right side.
LEFT Clip: Normal findings with the diaphragm in the middle and the liver on the right. The curtain sign is present, with no fluid and no spine sign.
RIGHT Clip: Abnormal findings with pleural effusion in the right pleural cavity. No curtain sign is seen; instead, a black anechoic fluid mass is visible above the diaphragm, along with the spine sign.
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This ultrasound clip demonstrates the “mirror sign” artifact. A gray ‘mass’ above the diaphragm may appear suspicious for pleural effusion. However, the presence of the curtain sign and the absence of the spine sign confirm that pleural effusion is not present.
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This clip shows pleural effusion in the right pleural cavity. The diaphragm and liver are visible on the right side, with fluid seen above the diaphragm. The absence of the curtain sign and the presence of the spine sign confirm pleural effusion in the patient’s right thoracic cavity.
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This clip shows a small collection of pleural fluid in the right pleural cavity. The diaphragm and liver are visible on the right side. The absence of the curtain sign and the presence of the spine sign indicate a small pleural effusion in the patient’s right thoracic cavity.
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This clip shows a large pleural effusion in the left thoracic cavity. The spleen is seen below the diaphragm, with fluid visible above it. The absence of the curtain sign and the presence of the spine sign confirm the effusion. A small rim of compressed lung tissue is visible above the diaphragm within the fluid.
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Another clip shows pleural effusion in the right pleural cavity. The diaphragm and liver are visible on the right side, with fluid seen above the diaphragm. The absence of the curtain sign and the presence of the spine sign confirm pleural effusion in the patient’s right thoracic cavity.
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This clip shows an extremely large pleural effusion almost filling the right hemithorax. The diaphragm and liver are visible on the right side, with fluid seen above the diaphragm. The absence of the curtain sign and the presence of the spine sign confirm pleural effusion in the patient’s right thoracic cavity. A fully compressed right atelectatic lung is seen, demonstrating the “jellyfish sign,” where the collapsed lung appears to “swim” within the large pleural effusion.
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This clip shows an extremely large pleural effusion in the left hemithorax. The fluid almost fills the thoracic cavity, and the “jellyfish sign” is visible, with the fully compressed left lung “swimming” within the effusion. The beating heart is also seen clearly, appearing in an unusual projection as the ultrasound transducer views it from the posterolateral aspect of the pleura, with fluid surrounding the heart.
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This example illustrates how a large pleural effusion can be mistaken for a pericardial effusion when examining the heart. The clip shows an apical four-chamber view of the heart in a patient with a significant pleural effusion in the right thoracic cavity. The anechoic black fluid appears in close proximity to the heart, resembling a pericardial effusion, as seen in cardiac tamponade. However, the absence of heart chamber compression suggests the fluid is in the pleural space. To confirm pleural effusion, an ultrasound from the posterolateral view of the lung and pleura should be performed.