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Key Clinical Questions

  • image When does a pleural effusion require drainage?

  • image Why make the distinction between transudates and exudates?

  • image How does the pleural fluid analysis assist in guiding your differential diagnosis?

  • image When is a chest tube placement indicated?

  • image When should a pulmonary consultation be obtained?

The seven leading causes of pleural effusions in the United States, in descending order include: (1) congestive heart failure; (2) bacterial pneumonia; (3) malignancy; (4) pulmonary embolism; (5) viral disease; (6) postcoronary artery bypass surgery; and (7) cirrhosis with ascites. Pneumothorax in the hospitalized patient is most commonly found in (1) blunt trauma (35%); (2) transthoracic needle aspiration biopsies (25%); (3) pleural biopsies (8%); (4) transbronchial lung biopsies (6%); (5) mechanically ventilated patients (4%); (6) thoracentesis (2%); and (7) central line insertions (1%-2%). Spontaneous pneumothorax occurs in about 15,000 cases per year in the United States: primary spontaneous pneumothorax occurs in adults with no underlying lung disease, whereas secondary spontaneous pneumothorax occurs in older adults with underlying lung disease, most commonly with chronic obstructive pulmonary disease.


A thoracentesis should be performed in most patients with a pleural effusion (Table 236-1). Thoracentesis should be performed in patients with likely heart failure if the pleural effusion is unilateral, if one side is greater than the other, or if there is suspicion for a dual diagnosis. The major risks and complications of thoracentesis include the following: (1) pneumothorax; (2) bleeding; (3) infection; and (4) procedural related pain. There are no evidence based guidelines in patients with coagulopathies, and there are reports of thoracentesis being performed in patients with an elevated international normalized ratio, uremia, thrombocytopenia or on oral antiplatelet or anticoagulation therapies. The benefits of correcting coagulopathy with transfusions or by withholding antiplatelet or anticoagulation medications should be weighed against the risks in the individual patient and should always be discussed with the patient. Ultrasound should be performed in all patients undergoing thoracentesis to less the risk of complications associated with a blind tap. Ultrasound can identify the pleural fluid and other underlying anatomical structures, estimate the size of the effusion, and determine the presence of underlying septations or complexity that may indicate the presence of loculations (Figure 236-1) (see Chapter 124 [Thoracentesis]).

TABLE 236-1Indications for Thoracentesis
Figure 236-1

Ultrasound images show a large simple pleural effusion and a complex pleural effusion with septations. (A) Large simple anechoic pleural effusion causing atelectasis of the right lower lobe (arrow). The bright white line on the right (arrowheads) represents the diaphragm; the atelectatic ...

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