Pleural Effusion

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James Stevenson, M.D. Thoracic Medical Oncologist

Pleural effusion, or water on the lungs, is an abnormal buildup of fluid in the lining around the lungs (the pleura). The most common causes are heart failure, cancer and pneumonia. Symptoms include difficulty breathing, chest pain and a dry cough. Doctors may drain the fluid to reduce symptoms.

01. Overview

What Is Pleural Effusion?

Pleural effusion happens when extra fluid collects within the lining around the affected lung (the pleura). The pleura has two layers. In healthy people, the area between the layers (the pleural space) holds a small amount of fluid. This helps the layers slide smoothly when you breathe. Effusion occurs when fluid builds up beyond the normal amount.

Several conditions can trigger this buildup of excess pleural fluid, including mesothelioma. If enough fluid collects, it can press on the lung, making it difficult to breathe. Doctors may recommend draining the effusion to relieve this symptom.

Other Names for Pleural Effusion

  • Benign pleural effusion
  • Fluid around the lungs
  • Fluid between the lungs and chest wall
  • Fluid buildup on the lungs
  • Fluid in the chest
  • Hydrothorax
  • Malignant pleural effusion
  • Water on the lungs
02. Mesothelioma

Mesothelioma and Pleural Effusion

Pleural effusion is a common symptom of malignant pleural mesothelioma. Research suggests more than 95% of patients experience pleural effusion at some point. For many, it is the first noticeable sign of mesothelioma.

Pleural mesothelioma develops in the lining around the lungs. It is caused by asbestos. The mineral fibers can irritate and inflame the area, causing cancer to develop over time.

Pleural mesothelioma triggers effusion by increasing pleural fluid production and slowing its drainage. Tumor cells draw extra liquid into the pleural space. Mesothelioma cells can also spread to and block flow in the lymph nodes. This slows lymphatic drainage, causing pleural fluid to collect.

Many other conditions can lead to pleural effusions. This means fluid buildup can be triggered in different ways depending on the root cause.

03. Causes

Causes of Pleural Effusion

Heart failure, cancer and pneumonia are the most common causes of pleural effusions. These illnesses trigger effusion by increasing pleural fluid, decreasing its drainage or both. Other conditions can also cause pleural effusions.

Pleural Effusion Causes

Cancers That Cause Pleural Effusions

  • Blood cell cancers
  • Breast cancer
  • Lung cancer
  • Lymphoma
  • Mesothelioma

Non-Cancerous Conditions That Cause Pleural Effusions

  • Cirrhosis
  • Heart failure
  • Pneumonia
  • Pulmonary embolism (blood clot in the lung)
  • Tuberculosis

Pleural effusions may be malignant or benign, depending on the cause. Malignant pleural effusions are caused by cancer. Benign pleural effusions are caused by illnesses that are not cancer. Treatment options differ between these two effusion types.

What Is the Main Cause of Pleural Effusion?

Lung cancer is the most common cause of malignant pleural effusion. Congestive heart failure is the most common cause of benign pleural effusion.

Pleural effusions can also be categorized by the contents of the effusion fluid:

  • Protein-rich: This type of effusion contains a lot of protein and may be called an exudative effusion. It may be caused by cancers or inflammatory conditions. Protein-rich effusions are common among mesothelioma patients.
  • Watery: This type of effusion is considered protein-poor and may be called a transudative effusion. It may be caused by heart failure, cirrhosis or pulmonary embolisms.

Understanding the protein content of an effusion may help doctors pinpoint its cause. This information can also affect treatment options.

Asbestos-Related Pleural Effusion

Asbestos exposure may increase your risk of developing pleural effusion. Once inhaled, asbestos fibers can cause inflammation and illness, including effusions. In rare cases, exposure can cause benign asbestos pleural effusion (BAPE).

BAPE occurs when a patient has pleural effusion with no other cause except asbestos exposure. Patients with BAPE do not necessarily have mesothelioma but may develop it in the future.

04. Symptoms

Symptoms of Malignant Pleural Effusion

Pleural effusion commonly signals the presence of another condition. But the fluid buildup can cause its own symptoms. Pleural effusion symptoms include shortness of breath, chest pain, coughing and fatigue. Some patients may not have symptoms. In these cases, the effusion may be found incidentally.

Note: Malignant and benign pleural effusions may cause similar symptoms.

Symptoms of Pleural Effusion

  • Chest pain
  • Dry cough
  • Dyspnea (shortness of breath)
  • Fatigue
  • Fever
  • Orthopnea (inability to breathe easily unless sitting up or standing)

Symptoms can range from mild to severe based on the amount of fluid in the pleural space. The greater the amount of fluid, the more noticeable symptoms may become.

05. Diagnosis

How Is Pleural Effusion Diagnosed?

Doctors use several tests to investigate cases of suspected pleural effusion. Tests can include imaging scans like chest X-rays, ultrasound or CT scans. Doctors can also perform a physical exam.

To find the cause of pleural effusion, physicians may prescribe additional tests. For example, patients may undergo a biopsy to retrieve a sample of the effusion fluid. Technicians can analyze this fluid to help narrow down the underlying cause of fluid buildup.

Tests that can provide information on the cause of an effusion include:

These procedures may help doctors diagnose the root cause of pleural effusion and recommend an appropriate treatment.

Early Detection of Pleural Effusion Can Help Mesothelioma Patients

Early detection of pleural effusion may also lead to an early mesothelioma diagnosis.

Some patients with benign pleural effusion and past asbestos exposure may later develop pleural mesothelioma. In these cases, doctors can continue to monitor the patient for signs of mesothelioma. This may help with early diagnosis.

Earlier diagnosis generally comes with a more favorable mesothelioma prognosis. But life expectancy also depends on a patient’s cell type, age, overall health and other factors.

What is the life expectancy of someone with pleural effusion?

Pleural effusion prognosis depends on its cause and patient factors. 1-year survival rates for benign pleural effusions range from about 50% to 75%. For malignant pleural effusions, experts say patients live 1 – 2 years. But these estimates may vary depending on treatment choices and other factors.

06. Treatment

How Is Pleural Effusion Treated?

Pleural effusion treatments target the root cause. Doctors may treat effusions from heart failure with diuretics. Antibiotics treat infection-related effusions. Malignant pleural effusions are often treated by draining the fluid. Some approaches also aim to prevent future effusions.

Doctors treat pleural effusions in mesothelioma patients with short- or long-term solutions. Short-term approaches entail one-time drainage of excess fluid. Long-term options allow for repeated fluid drainage or seek to prevent future buildup.

Patients can receive these treatments alongside others, like immunotherapy or palliative care.

Pleural Effusion Treatment Options

Pleural Drain / Pleural Catheter

  • Type: Long-term, repeat drainage
  • Overview: A doctor places a catheter in the pleural cavity. The catheter remains in place, allowing drainage as necessary.

Pleurectomy/Decortication (P/D)

  • Type: Long-term, effusion preventive
  • Overview: P/D surgery removes tumors and the lining around the lung. Without the lining, fluid can’t collect in that space.

Pleurocentesis (Thoracentesis)

  • Type: Short-term, one-time drainage
  • Overview: A doctor uses a long, hollow needle to remove the effusion fluid. Pleurocentesis can reduce pressure on the lung and help improve symptoms like breathlessness.


  • Type: Long-term, effusion preventive
  • Overview: After draining the effusion, doctors help the two layers of the pleura stick to each other. Pleurodesis surgery closes the pleural space to prevent fluid buildup.

Pleuroperitoneal Shunt

  • Type: Long-term, repeat drainage
  • Overview: Doctors place a tube connecting the abdomen to the pleural space. The tube channels effusion fluid out of the pleural space, allowing it to be absorbed in the belly.

Video-Assisted Thoracoscopic Surgery (VATS)

  • Type: Short- or long-term
  • Overview: This minimally invasive approach uses cameras to guide pleural fluid drainage. Doctors may also use VATS for pleurodesis procedures.

Like all medical treatments, each option comes with its own risks and benefits. Patients should discuss these factors with a mesothelioma specialist. The doctor can explain which choices best fit an individual patient.

Talc Pleurodesis vs. Talc-Related Mesothelioma

Pleurodesis procedures cause the two layers of the pleura to stick to each other. Doctors commonly apply talc within the pleura to achieve this. The talc triggers irritation and scarring, essentially gluing the inner and outer pleura to each other.

But patients may worry about this approach, as talc has been linked to mesothelioma. Experts say this link stems from asbestos contamination. Talc naturally occurs in the same areas as asbestos. Without rigorous processing, talcum powders may still contain asbestos.

But medical talc is regulated as a drug and is subject to stringent quality controls. Only three talc products have approval for pleurodesis usage. Each is labeled as asbestos-free. You can ask your doctor to share the drug label for any talc that will be used in your procedure. Reading the label and confirming the talc is free of asbestos may help give you peace of mind.

07. Common Questions

Common Questions About Pleural Effusion

Can pleural effusion go away?

Minor pleural effusions may go away without treatment. More serious effusions can also go away with treatment. If treatment can address the cause of the effusion, it is more likely to resolve.

Who is more likely to get a pleural effusion?

People who smoke or drink alcohol may have a higher than average risk of developing pleural effusion. This is because smoking and drinking can cause heart, lung and liver problems, which can trigger effusion.

Is pleural effusion curable?

Doctors can treat pleural effusions. They may be able to cure some cases by treating the underlying cause. If the underlying cause cannot be treated, the effusion may require repeat treatment. Patients should discuss treatment options with their doctors to understand the likelihood of a cure.

What is the best treatment for pleural effusion?

For malignant pleural effusions, data indicates talc pleurodesis is the most effective chemical-based treatment. The best treatment for pleural effusion depends on the cause and patient factors. Doctors can weigh these variables and advise the best approach.