What is thoracentesis?

Thoracentesis is a surgical procedure which uses an image-guided needle to treat pleural effusion, which is an excess of fluids between the lungs and the chest wall.

A pulmonologist will carry out this procedure.

Why is thoracentesis performed?

Here are some of the common reasons why thoracentesis may be performed:

Diagnostic reasons:

Pleural effusion: Thoracentesis is often done to diagnose the cause of pleural effusion, which is the accumulation of fluid in the pleural space (the space between the lungs and the chest wall). The fluid sample collected during the procedure can help determine the underlying cause of the effusion, such as infection, cancer, heart failure, or inflammation.

Infection: When there is suspicion of a pleural infection, known as pleuritis or pleurisy, thoracentesis can help identify the infectious organism and guide appropriate treatment.

Cancer: Thoracentesis can be used to obtain pleural fluid for cytology, which involves examining the cells in the fluid under a microscope. This can help in the diagnosis of pleural malignancies (cancer that has spread to the pleural space).

Inflammatory conditions: Some autoimmune diseases, such as lupus or rheumatoid arthritis, can lead to pleural inflammation. Thoracentesis may be performed to assess the inflammatory markers in the pleural fluid.

Therapeutic reasons:

Pleural effusion relief: If a significant amount of fluid has accumulated in the pleural space and is causing symptoms such as chest pain, difficulty breathing, or coughing, thoracentesis can be performed to drain the excess fluid. This can provide immediate relief and improve respiratory function.

Pneumothorax: In cases of pneumothorax, which is the presence of air in the pleural space (outside the lung), thoracentesis may be used to remove the trapped air, allowing the lung to re-expand and preventing respiratory distress.

Preoperative evaluation: In some cases, thoracentesis may be performed prior to thoracic surgery to improve lung function or assess lung compliance.

What happens during thoracentesis?

The procedure begins with a chest X-ray to obtain images of your lungs. You’ll then receive some local anaesthesia in the area of ​​the back where the pleural puncture will take place.

This puncture involves introducing a needle above the rib inside the pleural space to extract a sample of the liquid that will be analysed in the laboratory. After the fluid is removed, the area will be bandaged over.

The whole procedure should take about 15 minutes and you will be able to go home straight away.

Preparing for thoracentesis

To prepare for thoracentesis you may have a blood test to see if your blood is clotting normally.

You’ll need to let the doctor know what medications you are taking, and whether you might be pregnant.

What does the exam feel like?

During the test, you feel an itch when injecting the local anaesthetic and then you can feel pressure or pain in the area when the needle is inserted into the pleural space (space between the chest wall and the tissue that lines the organs of the chest wall).

It is important that the patient does not cough or move during the process as it could cause damage to the lung. If you feel chest pain or difficulty breathing during the procedure, you should tell the specialist.

What do abnormal results mean?

Once the pleural fluid is analysed, if the results are abnormal, this could indicate:

• congestive heart failure (the most common cause of pleural effusion, where the blood doesn’t properly pump blood out of your body)
• pulmonary hypertension
• a chest infection such as pneumonia or tuberculosis
• a blood clot in the lung
• empyema