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What is a Thoracentesis?

Thoracentesis is a minimally invasive procedure performed by a radiologist in which fluid that has collected in the pleural space between the lungs and the chest wall is drained through an inserted needle. The fluid buildup is called a pleural effusion and may be caused by a variety of different medical conditions. A large pleural effusion can partially compress your lung and can make it difficult to breathe.

Thoracentesis may be a diagnostic or therapeutic procedure. If the cause of the pleural effusion is uncertain, diagnostic thoracentesis is performed, and a sample of the fluid is sent to a lab for analysis in order to determine the cause. Therapeutic thoracentesis is often performed as a comfort measure in people with known causes of pleural effusion to remove excess fluid and relieve pressure as part of the treatment plan.

Patient Education Video

How Should I Prepare?

If you are taking prescribed anticoagulants (blood thinners) such as Coumadin or Plavix, you should ask your physician for instructions prior to the procedure. Patients should not take over-the-counter aspirin or aspirin-containing medications for at least 5 days prior to their thoracentesis. Please consult with your doctor or healthcare provider before stopping ANY medications.

You will be asked not to eat for 6 hours prior to the procedure. You will be encouraged to drink clear liquids up to 2 hours before the procedure and asked to take nothing by mouth after that.

Please arrive for your thoracentesis with a responsible adult who can drive you home.

What Should I Expect?

After you arrive for your appointment, you will be escorted to a procedure room, where you will be asked to change into a patient gown. You will be positioned on an exam table, and ultrasound will be used to locate the fluid and choose the most appropriate puncture site. The skin will then be cleansed, and a small amount of local anesthetic (lidocaine) will be injected into the skin with a small needle. You will feel a tiny pinch similar to a pinprick while the anesthetic is injected.

After the area becomes numb, the radiologist will insert the thoracentesis needle and connect it to tubing that will drain the fluid into a vacuum bottle. The radiologist will tell you not to move, cough, or breathe deeply once the procedure begins. After an appropriate amount of fluid has been collected, the needle will be removed, and a bandage will be applied.

If a large amount of fluid is withdrawn, your lungs will have more room to fill with air, which should make it easier to breathe. A chest X-ray may be obtained after the procedure. You will be monitored for at least 20-30 minutes prior to discharge.

For your safety and the protection of others, we do not allow anyone other than patients in our exam rooms.

Are There Potential Side Effects or Complications?

Most thoracentesis procedures are very well tolerated, with minimal discomfort afterwards that is usually easily controlled with non-prescription pain medication. Significant complications associated with thoracentesis are uncommon. The primary risk associated with this procedure is a pneumothorax (collapsed lung), with other risks including bleeding and infection. However, if you experience increasing pain, shortness of breath, or weakness after returning home, contact your physician or healthcare provider immediately.

How Do I Get the Results?

If your thoracentesis is diagnostic in nature, your doctor or healthcare provider will receive separate reports from the radiologist and the laboratory where the fluid sample was sent for analysis. After receiving these reports, your doctor or healthcare provider will be able to discuss the results with you.

Reports are also available on the MyRAD Patient Portal