Pleural effusionArcot J Chandrasekhar, M.D.
Objectives:
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What is pleural effusion?
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What are the types of fluid that can accumulate in pleural space?
Cholesterol effusion from a patient with rheumatoid arthritis is shown. Radiologically they all look similar and cannot be distinguished in plain CXR. |
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What are the mechanisms by which fluid accumulates in pleural space?
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What are the imaging criteria for pleural effusion in CXR?Imaging criteria are:
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Before thoracentesis Left diaphragm is not identifiable |
After thoracentesis Left diaphragm is seen clearly. |
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How do you differentiate complete opacification of one hemi thorax in CXR? Unilateral white out of thorax.Consider:
Mediastinum is shifted to the opposite side with effusion and pulled to same side with atelectasis. Hemi thorax is larger with effusion and smaller with atelectasis. There are other reasons for loss of unilateral lung volume, but for now remember atelectasis and resection. |
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Massive effusion on left
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Atelectasis of left lung
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What are the different appearances of pleural effusion?
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Unilateral haziness Supine film on left. Note uniform haziness of right hemi thorax. Upright film on right is now showing sub pulmonic effusion |
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How do you recognize loculated effusion? What is the significance?
Note in the upright film on right you are able to see the diaphragm medially, indicating that the fluid is not in the dependent portion. Empyemas loculate. Consider all loculated effusions as empyema unless proven otherwise. |
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When will you order lateral decubitus film?Lateral decubitus film is obtained:
Most of the time it is ordered unnecessarily with no additional benefit in large effusions. Note in the film on right shows the findings of sub pulmonic effusion. The costophrenic angle (black arrow head) is blunted and displaced medially. The distance between the stomach bubble and diaphragm has increased (Black arrow). In the lateral decubitus film fluid layers along the ribs (white arrow heads).
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What are the other imaging procedures of value in the evaluation of pleural effusion?
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How does radiological procedures help in thoracentesis?You do not need any radiological assistance to tap most of the effusions. Obtain radiological assistance to tap:
Ultrasound is the preferred method for localization of fluid and a needle can be passed through the probe. It can also be done at the bedside if necessary. CT guided tap is equally effective, except it is not useful as bedside procedure. |
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When you are considering pleural effusion as your final impression you should
make the following statements, why you concluded that it is pleural effusion.
How do you determine the etiology of effusion from chest x-ray?Radiologically you cannot distinguish transudate, exudate, blood or pus. It's mainly the associated findings suggest the etiology. Let me give a few scenarios: Bilateral: consider transudative effusions first. You will need clinical information.
Bilateral effusions with cardiomegaly: Congestive heart failure Bilateral pleural effusions associated with ascites in a alcoholic: Cirrhosis Unilateral: most of them are exudative
Massive unilateral effusion: Malignancy Pleural effusion with apical infiltrates: Tuberculosis Pleural effusion with nodes or mass or lytic bone lesions: Malignancy Loculated effusions are empyemas Pleural effusion with a missing breast suggesting resection for cancer : Malignancy Pleural effusion following chest trauma: Hemothorax In patients with mediastinal lymphoma : Chylothorax Unique etiologies for left sided effusions
Unique etiologies for right sided effusions
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