Pleural Effusion Drainage

Thoracentesis is a procedure to remove fluid from the space between the lining of the outside of the lungs (pleura) and the wall of the chest.

How the Test is Performed 

A small area of skin on your chest or back is washed with a sterilizing liquid. Some numbing medicine (local anesthetic) is injected in this area.

A needle is placed through the skin of the chest wall into the space around the lungs, called the pleural space. Fluid is collected and may be sent to a laboratory for testing (pleural fluid analysis).

How to Prepare for the Test 

No special preparation is needed before the test. A chest x-ray may be performed before and after the test.

Do not cough, breathe deeply, or move during the test to avoid injury to the lung.

How the Test Will Feel 

You will sit on a bed or on the edge of a chair or bed. Your head and arms will rest on a table.

The skin around the procedure site is cleaned and the area is draped. A local numbing medicine (anesthetic) is injected into the skin. The thoracentesis needle is inserted above the rib into the pleural space.

You will feel a stinging sensation when the local anesthetic is injected. You may feel pressure when the needle is inserted into the pleural space.

Tell your health care provider if you feel shortness of breath or chest pain.

Why the Test is Performed 

Normally, very little fluid is in the pleural space. A build-up of too much fluid between the layers of the pleura is called a pleural effusion.

The test is performed to determine the cause of the extra fluid, or to relieve symptoms from the fluid build-up.

Normal Results 

Normally the pleural cavity contains only a very small amount of fluid.

What Abnormal Results Mean 

Testing the fluid will help your health care provider determine the cause of pleural effusion. Possible causes include:

  • Cancer
  • Cirrhosis
  • Heart failure
  • Infection
  • Kidney disease

If your health care provider suspects that you have an infection, a culture of the fluid may be done to test for bacteria.

The test may be also performed for the following conditions:

  • Asbestos-related pleural effusion
  • Collagen vascular disease
  • Drug reactions
  • Hemothorax
  • Pancreatitis
  • Pneumonia
  • Pulmonary embolism
  • Pulmonary veno-occlusive disease
  • Thyroid disease


  • Bleeding
  • Fluid build-up
  • Infection
  • Pneumothorax
  • Pulmonary edema
  • Respiratory distress


A chest x-ray is often done after the procedure to detect possible complications.

When there is potential for reacumulation of the fluid on a regular bases your doctor may recommend that a long term drainage catheter be placed on your chest. This is an innovative approach to home management of pleural effusions. The catheter is a short tube with drainage holes which is inserted into the chest cavity by an Interventional Radiologist. The end of the catheter protrudes through the skin and has a valve that prevents leakage of fluid when not in use. This end is protected by a dressing that ensures comfort and discretion.

If you have any questions or need to reschedule an appointment please feel free to contact the Interventional Radiology Office at 802- 847-8359. Our business hours are Monday – Friday 8:30 a.m. to 5 p.m. Someone is available to take your call after hours for emergencies.

This information is provided by the Fletcher Allen Health Care, Department of Radiology, Division of Interventional Radiology and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact your health care provider.