Pleural effusion

Pleural effusion is an abnormal buildup of fluid in the pleural cavity. The pleural cavity is the space between the lungs and the chest wall. The fluid builds up between the 2 layers of the pleura, which is a thin layer of tissue that covers the lungs and lines the chest wall. When pleural effusion is related to cancer or there are cancer cells in the fluid, it may be called malignant pleural effusion.


Pleural effusion can be caused by cancer cells spreading to the pleura. It can also develop if cancer cells block or change the flow of lymph fluid in the pleural cavity.

The following cancers are more likely to cause pleural effusion:

  • lung cancer
  • breast cancer
  • non-Hodgkin lymphoma
  • Hodgkin lymphoma
  • ovarian cancer
  • leukemia
  • melanoma
  • mesothelioma
  • uterine cancer
  • cervical cancer
  • stomach cancer
  • sarcomas
  • cancer of unknown primary (CUP)


Pleural effusion may not cause any symptoms at first, or the symptoms may be mild. Symptoms of pleural effusion can vary depending on the amount of fluid and how quickly it builds up. They include:

  • shortness of breath or difficulty breathing, which is called dyspnea
  • cough
  • pain or a feeling of heaviness in the chest
  • anxiety
  • fear of suffocation
  • fever
  • malaise, which is general feeling of discomfort or illness

If shortness of breath, or dyspnea, gets worse when you lie down, it is called orthopnea. It might get better if you stand or sit up. Shortness of breath may lead to you being more tired than usual because it can wake you up at night.


Pleural effusion is usually diagnosed by:

  • physical exam
  • chest x-ray
  • CT scan

A CT scan may be able to diagnose small effusions. If pleural effusion is seen on an x-ray or CT scan, your doctor may do a thoracentesis. During this procedure, a needle is used to collect a sample of the fluid in the pleural cavity so it can be looked at under a microscope. The doctor may use ultrasound to guide the needle during thoracentesis.

Find out more about these tests and procedures.

Treating pleural effusion

If you have pleural effusion, your healthcare team will monitor you closely and suggest ways to treat it. Fluid often builds up again after it is removed, so you may need more than one treatment. You may be offered the following treatment options for pleural effusion.

Draining the fluid

Thoracentesis may be used to drain extra fluid around the lungs. Your doctor will insert a hollow needle between the ribs into the pleural cavity. The needle is used to remove the fluid.

Find out more about thoracentesis.


Surgery is often used to treat malignant pleural effusion.

Pleurodesis may be done if the fluid builds up in the pleural cavity again after thoracentesis. It is often done using video-assisted thoracoscopic surgery (VATS), which uses a thoracoscope with a video camera. During pleurodesis, your surgeon places a tube into the pleural cavity to drain the extra fluid. Then a chemical, called a sclerosing agent, is inserted into the tube and the tube is clamped for a period of time. The sclerosing agent seals the 2 layers of pleura together, which prevents fluid from building up again. Sclerosing agents include doxycycline (Vibramycin), bleomycin (Blenoxane) or talc. Once the layers are sealed, the tube is unclamped and the fluid drains into a bag or bottle. Your surgeon may need to repeat this procedure over several days.

The surgeon may also need to remove part of the pleura if fluid keeps building up in the pleural cavity. This surgery is called pleurectomy.

Cancer treatment

Your doctor will treat the cancer that has caused pleural effusion. Treatment will depend on the type of cancer. You may receive chemotherapy, hormonal therapy, radiation therapy or a combination of these treatments.


Your healthcare team may prescribe different drugs depending on the causes and symptoms of pleural effusion.

Your doctor will prescribe antibiotics if you have an infection. You may also be given steroids or nonsteroidal anti-inflammatory drugs (NSAIDs) to relieve pain and reduce inflammation or swelling.

If you have a small effusion that is developing slowly, you may be given a diuretic. A diuretic is a drug that helps the body get rid of extra fluid by increasing the amount of urine it makes.

Improving breathing

Your healthcare team will also take measures to help you breathe easier. They may prescribe bronchodilators. These drugs widen the tubes (called bronchi and bronchioles), or airways, in the lungs. This allows more airflow into the lungs.

Opioids are a type of narcotic pain medicine that may be used to ease shortness of breath.

Oxygen therapy is a treatment that gives you extra oxygen. It makes sure you get enough oxygen if you have trouble breathing. You breathe the oxygen in through a mask over your mouth or through tubes in your nostrils.

Expert review and references

  • Buckhoz GT, von Gunten CF . Diagnosis and management of effusions. Berger AM, Shuster JL Jr, & Von Roenn JH (eds.). Principles and Practice of Palliative Care and Supportive Oncology. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2013: 16: pp. 210-222.
  • Kwong KF, Nguyen DM . Malignant effusions of the pleura and the pericardium. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles & Practice of Oncology. 9th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2011: 151: pp. 2205 - 2213.
  • Pleural effusion. Macmillan Cancer Support. Macmillan Cancer Support. London, UK: Macmillan Cancer Support; 2013.
  • Malignant pleural effusion. National Cancer Institute. Cardiopulmonary Syndromes (PDQ®) Health Professional Version. Bethesda, MD: National Cancer Institute; 2011.
  • Rubins J . Pleural effusion treatment & management. WebMD LLC; 2012.
  • Turner Story K . Malignant pleural effusion. Kaplan M (Ed.). Understanding and Managing Oncologic Emergencies. 2nd ed. Pittsburgh: Oncology Nursing Society; 2013: 7: pp. 257 - 286.