Last revised by Andrew Murphy on 23 Mar 2023

Thoracentesis, commonly known as a pleural tap or chest tap, is a procedure where excess pleural fluid is drained from the pleural space for diagnostic and/or therapeutic reasons. Ultrasound-guided thoracentesis performed by radiologists has been shown to have fewer complications than blind thoracentesis. A success rate of up to 90% has been demonstrated after failed blind thoracentesis. 

  • symptomatic pleural effusions

  • investigation of cause of pleural fluid collection, e.g. malignancy, infection, etc

  • coagulopathy/thrombocytopenia, anticoagulation or other bleeding disorders

  • respiratory disease such as severe respiratory failure, intractable coughing, contralateral pneumonectomy, emphysema, suspected echinococcal disease or the inability to hold one's breath 7

Thoracentesis can be performed blind, partially imaged-guided or image-guided (usually ultrasound but may be CT). Below the technique for an ultrasound-guided  therapeutic thoracentesis with a trocar technique is outlined as this is the most commonly performed in radiology 12. Seldinger technique is an alternative method. 

  • review history, pathology results and prior imaging

    • e.g. 75% of pleural effusions secondary to congestive cardiac failure will resolve with two days of diuresis and thoracentesis should be reserved for refractory cases 3

  • obtain informed written consent

  • completion of a "time-out" with nursing staff

  • patient sitting on edge of bed, leaning forward with arms on a table

  • monitoring (BP, pulse rate, SpO2)

  • access from behind the patient

  • ultrasound with CH-4 probe

  • sterile pack including wash, gown and gloves, drape, ultrasound cover and sterile gel

  • long hypodermic needle, syringe and lignocaine

  • scalpel

  • thoracentesis/paracentesis catheter-over-needle set

  • three-way tap and drainage bag

  • dressings

  • pre-procedure ultrasound to confirm presence of drainable pleural effusion

  • sterile glove and gown followed by sterile preparation and drape

  • subcutaneous and deep infiltration to pleura of local anesthetic under ultrasound guidance

  • small skin nick with scalpel

  • under ultrasound guidance, introduction of thoracentesis needle along the superior margin of the rib, aspirating while advancing until pleural fluid is aspirated; catheter is then slid off needle

  • connection of three-way tap and underwater seal/vacuum/drainage system and airtight dressing applied

  • for diagnostic thoracentesis 50 mL of fluid is usually required 3

  • volume to be drained varied depending on the number of prior taps

    • ~1500 mL or until symptoms such as vague chest pain commence is recommended to reduce the occurrence of re-expansion pulmonary edema 4,5,9

    • some authors believe it is safe to drain larger volumes 10,11

  • requirement for post-thoracentesis chest x-ray to assess for pneumothorax is debated; literature has demonstrated there is a very low risk of pneumothorax in asymptomatic patients 1

  • patient should be advised of the risk of pneumothorax and not to fly for one week 6

Common complications from thoracentesis include 1,4:

Serious, but less common, complications from thoracentesis include 1,3,4:

  • in malignant pleural effusions, the average duration of symptom relief is 4 days and 99% of patients will reaccumulate pleural fluid 5

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