From the Guidelines
Thoracentesis is indicated for both diagnostic and therapeutic purposes in patients with pleural effusions, particularly when the etiology is unknown or when symptoms such as dyspnea, chest pain, or cough are present. The procedure is essential for diagnosing conditions by analyzing pleural fluid characteristics, including appearance, protein content, LDH levels, cell counts, cultures, cytology, and pH, which can differentiate between transudates and exudates and identify specific etiologies like infection or malignancy 1.
Diagnostic Indications
Diagnostic thoracentesis should be performed when the etiology of a pleural effusion is unknown, especially if the effusion is new, has concerning features on imaging, or occurs in a patient with risk factors for malignancy or infection. Specific diagnostic indications include:
- Parapneumonic effusions
- Malignant pleural effusions
- Hemothorax
- Empyema
- Chylothorax
Therapeutic Indications
Therapeutic thoracentesis is indicated to relieve symptoms caused by moderate to large effusions. The procedure involves inserting a needle into the pleural space to remove fluid for symptom relief. Typically, no more than 1.5 liters of fluid should be removed at once to prevent re-expansion pulmonary edema 1.
Contraindications
Thoracentesis is contraindicated in patients with:
- Bleeding disorders
- Anticoagulation therapy (unless corrected)
- Skin infection at the insertion site
- Severe respiratory compromise requiring mechanical ventilation
Recent Guidelines
Recent guidelines suggest that ultrasound imaging be used to guide pleural interventions in patients with known or suspected malignant pleural effusion (MPE) 1. Additionally, large-volume thoracentesis may be performed to assess lung expansion in symptomatic MPE patients with uncertain symptom relation to the effusion and/or expandable lung 1.
Volume of Fluid for Cytologic Evaluation
The volume of fluid needed for cytologic evaluation varies, but a study suggests that submitting more than 50 mL of pleural fluid does not increase the diagnostic yield 1. The diagnostic yield for malignancy depends on sample preparation, the experience of the cytologist, and the tumor type, with the highest diagnostic yields retrieved in patients with adenocarcinoma 1.
Management of Malignant Pleural Effusions
In patients with symptomatic MPE, either an indwelling pleural catheter (IPC) or chemical pleurodesis may be used as first-line definitive pleural intervention for management of dyspnea 1. In patients with IPC-associated infections, treating through the infection without catheter removal is usually adequate, but catheter removal may be necessary if the infection fails to improve 1.
From the Research
Indications for Thoracentesis
The following are indications for thoracentesis (pleural fluid aspiration):
- Pleural effusions of unknown origin and parapneumonic effusions almost invariably require thoracentesis 2
- New and unexplained pleural effusions require thoracocentesis to determine the etiology of the effusion 3
- Symptomatic pleural effusions, including those causing dyspnea, dry cough, and pleuritic chest pain, may require thoracentesis for diagnostic and therapeutic purposes 3, 4
- Recurrent symptomatic effusions can be managed with thoracentesis, pleurodesis, or placement of indwelling pleural catheters 5
- Large, refractory pleural effusions, whether transudate or exudate, must be drained to provide symptomatic relief 3
- Malignant effusions are usually drained to palliate symptoms and may require pleurodesis to prevent recurrence 3
Patient Selection
Patient selection for thoracentesis is crucial, and the procedure is generally safe when basic principles are considered 2. The decision to perform thoracentesis should be based on the individual patient's clinical presentation, underlying medical conditions, and the characteristics of the pleural effusion 4, 6.
Diagnostic Evaluation
The diagnostic evaluation of pleural effusion includes chemical and microbiological studies, as well as cytological analysis, which can provide further information about the etiology of the disease process 3. Immunohistochemistry can also provide increased diagnostic accuracy 3.
Therapeutic Uses
Thoracentesis can be used for therapeutic purposes, such as draining large, refractory pleural effusions to provide symptomatic relief 3. It can also be used to manage recurrent symptomatic effusions, including those caused by malignant disease 5, 3.