Editing Pleural effusions (section)

=== '''Causes of transudative pleural effusions''' ===
{| class="wikitable"
|'''Causes of transudative effusions'''
|'''Comment'''
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|'''Processes that ''always'' cause a transudative effusion'''
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|Atelectasis
|Caused by increased intrapleural negative pressure
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|Cerebrospinal fluid leak into pleural space
|Thoracic spinal surgery or trauma and ventriculopleural shunts
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|Heart failure
|Acute diuresis can result in borderline exudative features
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|Hepatic hydrothorax
|Rare without clinical ascites
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|Hypoalbuminemia
|Edema liquid rarely isolated to pleural space
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|Iatrogenic
|Misplaced intravenous catheter into the pleural space; post Fontan procedure
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|Nephrotic syndrome
|Usually subpulmonic and bilateral
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|Peritoneal dialysis
|Acute massive effusion develops within 48 hours of initiating dialysis
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|Urinothorax
|Caused by ipsilateral obstructive uropathy or by iatrogenic or traumatic GU injury
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|'''Processes that ''may'' cause a transudative effusion, but ''usually'' cause an exudative effusion'''
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|Amyloidosis
|Often exudative due to disruption of pleural surfaces
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|Chylothorax
|Most are exudative effusions 
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|Constrictive pericarditis
|Bilateral effusions
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|Hypothyroid pleural effusion
|From hypothyroid heart disease or hypothyroidism per se
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|Malignancy
|Usually exudative, but 3 to 10 percent transudative possibly due to early lymphatic obstruction, obstructive atelectasis, or concomitant disease (eg, heart failure)
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|Pulmonary embolism
|Most are exudative effusions
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|Sarcoidosis
|Stage II and III disease
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|Superior vena caval obstruction
|May be due to acute systemic venous hypertension or acute blockage of thoracic lymph flow
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|Coronavirus disease 2019 (COVID-19)
|Limited data profile the nature of pleural fluid in COVID-19-related pleural effusions, although transudative effusions have been reported 
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|Nonexpandable lung*
|A result of remote or chronic inflammation
|}