What is thoracentesis (pleural fluid aspiration)?

From the Guidelines

Thoracentesis is a medical procedure used to remove excess fluid from the pleural space between the lungs and chest wall, and it is recommended to diagnose the cause of the pleural effusion in patients suspected of having lung cancer who have an accessible pleural effusion, as stated in the American College of Chest Physicians evidence-based clinical practice guidelines 1.

Procedure Overview

The procedure typically takes 15-30 minutes and is done under local anesthesia (usually 1-2% lidocaine) with the patient sitting upright, leaning forward with arms supported.

• Ultrasound guidance is recommended to identify the optimal insertion site, typically between the 7th and 8th intercostal spaces in the mid-axillary line, as it improves the success rate and decreases the rate of pneumothorax 1.
• During the procedure, up to 1.5 liters of fluid may be safely removed at one time to prevent re-expansion pulmonary edema.

Indications and Analysis

Common indications include pleural effusions causing respiratory distress, effusions of unknown origin requiring diagnosis, or malignant effusions causing symptoms.

• The fluid removed is typically sent for analysis including cell count, protein, LDH, glucose, pH, cytology, and cultures to determine the underlying cause of the effusion, which could be infection, malignancy, heart failure, or other conditions.

Complications and Next Steps

Complications are rare but can include pneumothorax, bleeding, infection, or re-expansion pulmonary edema.

• If pleural fluid cytology is negative, pleural biopsy (via image-guided pleural biopsy, medical or surgical thoracoscopy) is recommended as the next step, as stated in the guidelines 1.
• Depending on preferences and values, a second thoracentesis may be considered before proceeding to biopsy of the pleura, as it has been shown to increase the diagnostic yield of pleural fluid cytology 1.

From the Research

Definition and Purpose of Thoracentesis

• Thoracentesis, also known as pleural fluid aspiration, is a medical procedure used for diagnostic and therapeutic purposes 2, 3, 4, 5, 6.
• The procedure involves removing pleural fluid from the pleural space to diagnose and treat various conditions, such as pleural effusions, pneumonia, and malignancies.

Diagnostic Thoracentesis

• Diagnostic thoracentesis is used to separate exudates from transudates and to analyze the fluid for infection, malignancy, and other conditions 2, 3, 6.
• The analysis of exudative fluid has the highest yield when infection and malignancy are likely 2.
• Ultrasound may be used to guide the procedure and decrease morbidity, especially when small or loculated volumes of fluid are present 2, 5, 6.

Therapeutic Thoracentesis

• Therapeutic thoracentesis is used to relieve symptoms of dyspnea and to remove large volumes of pleural fluid 2, 4, 5.
• The procedure can be performed using small-gauge needles and ultrasound guidance to minimize complications, such as pneumothorax 2, 5.
• Pleural manometry can be used to measure pleural pressure and predict the ability to perform pleurodesis in patients with malignant effusions 5.

Complications and Safety

• Pneumothorax is the most common major complication of thoracentesis, but it can be minimized by using small-gauge needles and ultrasound guidance 2, 5.
• The procedure is generally safe, but caution is needed when performing therapeutic thoracentesis, especially in patients with large pleural effusions or those receiving ventilator support 2, 5.