Pleural aspiration, or thoracocentesis, is a procedure to remove fluid from the pleural space (pleural effusion) for diagnostic or therapeutic purposes.
Indications
Diagnostic
- Evaluation of unilateral exudative pleural effusions
- Suspected malignancy
- Suspected infection (e.g., empyema)
- Cytological analysis (e.g., for malignancy)
- Microbiological studies (gram stain, culture, acid-fast bacilli)
- Biochemical analysis (protein, glucose, LDH, ADA)
Therapeutic
- Relief of dyspnea due to moderate to massive effusions
- Management of pyothorax
- Recurrent malignant effusions
- Instillation of agents (e.g., chemotherapy, sclerosing agents)
⚠️ Note: Do not aspirate bilateral or known transudative effusions unless atypical features or treatment failure is observed.
Contraindications
Absolute
- Local skin infection at puncture site
- Uncorrected coagulopathy or platelet count <20,000/μL
Relative
- Very small volume of fluid
- Anticoagulant therapy (e.g., warfarin)
- Mechanical ventilation (↑ risk of tension pneumothorax)
- Known bleeding diathesis
Site of Aspiration
- 6th intercostal space (mid-axillary line)
- 7th intercostal space (posterior axillary line)
- 8th intercostal space (scapular line)
Choose the site 1–2 intercostal spaces below the upper level of dullness, and always above the 8th rib to avoid injury to abdominal organs.
Equipment
- Sterile gloves and field
- Ultrasound with sterile probe cover
- Chlorhexidine or povidone-iodine
- Local anesthetic (e.g., 1–2% lignocaine, max dose: 3 mg/kg)
- 50 mL syringe
- Pleural aspiration needle (with 3-way stopcock)
- Specimen containers (for cytology, biochemistry, microbiology)
Procedure Overview
- Positioning: Patient seated upright, leaning slightly forward with arms resting on a table or pillow.
- Ultrasound guidance to locate fluid and avoid injury.
- Aseptic technique and skin preparation.
- Local anesthesia infiltration to skin and pleura.
- Needle insertion: Just above the superior border of the rib to avoid intercostal neurovascular bundle.
- Aspirate fluid using a syringe via a 3-way stopcock.
- Fluid examination:
- Odor: Putrid (anaerobic infection), milky (chylothorax), bloody (hemothorax)
- Color: Serous, cloudy, purulent
Sample Volume
- Diagnostic: ~50 mL is sufficient
- Therapeutic: Do not exceed 750–1000 mL per session to prevent reexpansion pulmonary edema
🧠 If the patient develops cough or respiratory distress, stop the procedure immediately.
Post-procedure
- Monitor for complications (e.g., pneumothorax)
- Chest X-ray if clinically indicated
- Repeat aspiration every 3–4 days if necessary
Complications
- Pneumothorax / Hydropneumothorax
- Reexpansion pulmonary edema
- Hemothorax
- Pleural infection (pyothorax)
- Injury to intercostal vessels or nerves
- Air embolism
- Intercostal artery aneurysm
- Pleural shock
Dry Tap (No fluid aspirated)
Causes:
- Thick pus (empyema)
- Lung parenchymal lesion simulating effusion (e.g., tumor, consolidation)
- Loculated effusion
- Pleural thickening or fibrosis
- Subpulmonic or interlobar effusion
Cytology and Laboratory Processing
- Immediate submission of unfixed specimen
- Wet mount technique: Toluidine blue stain for cell morphology
- Preparation of cell blocks for histochemistry or immunohistochemistry
- Ancillary tests: Flow cytometry, electron microscopy
