page_title: Pleural effusion
section_title: Exudative
hierarchical_section_title: Pleural effusion / Causes / Exudative
caption_attribution_description: English: Pleural effusion Chest x-ray of a pleural effusion. The arrow A shows fluid layering in the right pleural cavity. The B arrow shows the normal width of the lung in the cavity
context_page_description: A pleural effusion is excess fluid that accumulates in the pleural cavity, the fluid-filled space that surrounds the lungs. This excess fluid can impair breathing by limiting the expansion of the lungs. Various kinds of pleural effusion, depending on the nature of the fluid and what caused its entry into the pleural space, are hydrothorax, hemothorax, urinothorax, chylothorax, or pyothorax commonly known as pleural empyema. In contrast, a pneumothorax is the accumulation of air in the pleural space, and is commonly called a "collapsed lung".
context_section_description: When a pleural effusion has been determined to be exudative, additional evaluation is needed to determine its cause, and amylase, glucose, pH and cell counts should be measured.
  Red blood cell counts are elevated in cases of bloody effusions (for example after heart surgery or hemothorax from incomplete evacuation of blood).
  Amylase levels are elevated in cases of esophageal rupture, pancreatic pleural effusion, or cancer.
  Glucose is decreased with cancer, bacterial infections, or rheumatoid pleuritis.
  pH is low in empyema (<7.2) and may be low in cancer.
  If cancer is suspected, the pleural fluid is sent for cytology. If cytology is negative, and cancer is still suspected, either a thoracoscopy, or needle biopsy of the pleura may be performed.
  Gram staining and culture should also be done.
  If tuberculosis is possible, examination for Mycobacterium tuberculosis (either a Ziehl–Neelsen or Kinyoun stain, and mycobacterial cultures) should be done. A polymerase chain reaction for tuberculous DNA may be done, or adenosine deaminase or interferon gamma levels may also be checked.
  The most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism.
  Another common cause is after heart surgery, when incompletely drained blood can lead to an inflammatory response that causes exudative pleural fluid.
  Conditions associated with exudative pleural effusions:
  Parapneumonic effusion due to pneumonia
  Malignancy (either lung cancer or metastases to the pleura from elsewhere)
  Infection (empyema due to bacterial pneumonia)
  Trauma
  Pulmonary infarction
  Pulmonary embolism
  Autoimmune disorders
  Pancreatitis
  Ruptured esophagus (Boerhaave's syndrome)
  Rheumatoid pleurisy
  Drug-induced lupus
caption: Pleural effusion Anteroposterior Chest X-ray of a pleural effusion. The A arrow shows fluid layering in the right pleural cavity. The B arrow shows the normal width of the lung in the cavity
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "243", "Image YResolution": "243", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop 7.0", "Image DateTime": "2005:10:20 23:32:31", "Image ExifOffset": "156", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "294", "Thumbnail JPEGInterchangeFormatLength": "3112", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "475", "EXIF ExifImageLength": "382"}