What is thoracentesis?
Thoracentesis (also known as pleural fluid analysis) is a procedure that drains fluid from the area around the lungs (pleural space) through a needle or tube. Normally, very little fluid is present in the pleural space; however, some conditions can cause the build-up of excess fluid between the layers of the pleura. This build-up of fluid is called a pleural effusion.
Who is a candidate for thoracentesis?
People who have been diagnosed with a pleural effusion are candidates for a thoracentesis. Often, the build-up of excess fluid in the pleural space causes symptoms such as shortness of breath and cough.
Why is a thoracentesis needed?
In addition to relieving a patient’s symptoms, thoracentesis can help your physician better determine the cause of the pleural effusion so the condition can be more appropriately treated. A pleural biopsy may also be completed at the same time as a thoracentesis to collect a sample of tissue from the inner lining of the chest wall.
What tests are needed before a thoracentesis?
Tests most commonly used prior to a thoracentesis include:
- Chest x-ray (to identify the location of the pleural effusion)
- Ultrasound of the chest
- Blood tests (such as a complete blood count, or CBC, to exclude any blood clotting abnormalities)
You will meet with several health care providers, including your surgeon, who will ask questions about your condition and health history. Certain conditions may increase the difficulty of completing a thoracentesis. Let your physician know if you:
- Have undergone lung surgery. The scarring from lung surgery may make it difficult to complete thoracentesis.
- Have a long-term (chronic), irreversible lung disease, such as emphysema.
Thoracentesis may not be completed on people who:
- Have a bleeding disorder.
- Have heart failure or enlargement of the right side of the heart.
- Take an anticoagulant (blood-thinning) medication.
How is thoracentesis completed?
A thoracentesis generally takes 10 to 15 minutes to complete, and can be performed at your bedside or in an outpatient office setting.
During the thoracentesis:
- You will be placed in a position that allows your physician to easily access the effusion. Typically, you will be asked to sit upright on the side of a bed or examining table and to remain still while the procedure is performed.
- Before the needle is inserted into the lower ribs, the skin in the area is cleaned with an antibacterial solution and a local anesthetic (similar to novocaine) is administered. The catheter (small, thin tube) is typically inserted between the ribs in the back of your chest.
- As the catheter is advanced into the pleural space, you may feel some discomfort. To ease any aching, take slow, deep breaths and try to relax your back muscles.
- As fluid is drained from the space you may feel like coughing. This is a normal reflex. An effusion that causes symptoms, such as shortness of breath, may require that a large amount of fluid be removed to allow the lung to re-expand.
- After the catheter is removed, a small amount of pressure is applied to the insertion site followed by a dressing or adhesive bandage placed over the site.
Following the thoracentesis:
- You will be allowed to rest in the bed or on the examining table. Soon after, a chest x-ray will be performed.
- If you feel more short of breath than usual, tell your nurse of doctor immediately.
- Your physician may order a follow-up chest x-ray two to four weeks later.
What are the risks of a thoracentesis?
Thoracentesis is generally a safe procedure and complications occur less when thoracentesis is performed under ultrasound guidance. Accordingly, most patients will undergo an ultrasound to assess the effusion just prior to the thoracentesis procedure. While complications may occur, most of these are minor and resolve on their own or are easily treated.
Complications may include:
- Pain, which may occur during the procedure, and generally resolves once the catheter is removed.
- Infection and bleeding.
- Pulmonary edema, where additional excess fluid builds up in the lungs, which may occur if a large amount of fluid is removed.
- A partial collapse of the lung (pneumothorax), which may occur if the lung is injured while it reinflates. This complication occurs about 10 percent of the time, those pneumothoraces are small and often resolve on their own. If the pneumothorax is large, continues to expand, or causes symptoms, a chest tube may be inserted to help re-expand the lung and a hospital admission may be required.
- Rarely, damage to the liver or spleen through a puncture.
Thoracentesis, UptoDate, Sahn, SA, May 15, 2006. patients.uptodate.com/topic.asp?file=lung_dis/5879
Thoracentesis, Merck Medical Manual, November 2005, www.merck.com/mmpe/sec05/ch047/ch047i.html#sec05-ch047-ch047j-265
Colice G L, Curtis A, Deslauriers J, Heffner J, Light R, Littenberg B, Sahn S, Weinstein R A, Yusen R D. "Medical and Surgical Treatment of Parapneumonic Effusions: An Evidence-Based Guideline." Chest, 2000; 118;1158-1171.
Jones PW, Moyers JP, Rogers JT, Rodriguez RM, Lee YC, Light RW. Ultrasound-guided thoracentesis: is it a safer method? Chest. 2003 Feb;123(2):418-23.
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