What Is a Pleural Effusion?

A pleural effusion is the accumulation of excess fluid in the space between the lungs and chest cavity. Also known as “water on the lungs,” pleural effusions are often a sign of more advanced disease such as lung cancer, heart failure or mesothelioma.

Surrounding the lungs and lining the chest cavity are two layers of tissue called the pleura. The pleura protects the lungs and helps them expand and contract during breathing. In healthy patients, there is some fluid between the layers of pleura which lubricates the lungs and assists with movement during respiration.

Too much fluid in the pleural cavity, the space between the pleural layers, causes excess pressure on the lungs. Pleural effusions limit lung movement and lead to shortness of breath.

In 2019, a research study reported that 33% of mesothelioma patients who had developed a pleural effusion lost the ability to expand the affected lung.

Malignant pleural effusion is the first clinical presentation in over 90% of mesothelioma patients.
Source: Respirology Case Reports, 2018

Pleural effusions without complications are not typically fatal and may resolve on their own, but their presence indicates a more severe issue that requires treatment. Recurrent pulmonary effusions and long-term lung damage are likely to occur if a doctor does not treat the underlying cause.

Mesothelioma and Pleural Effusions

Pleural effusions are strongly associated with asbestos-related diseases such as malignant pleural mesothelioma, asbestosis, lung cancer and breast cancer. They are often the first clinical presentation that leads to a diagnosis of the underlying condition.

Those with a history of asbestos exposure should be aware of the dangers of pleural effusion. Multiple or untreated pleural effusions can cause permanent damage to the lungs, which can add to damage caused by asbestos exposure. Pleural effusions and asbestos both cause pleural thickening, an accumulation of scar tissue on the pleura that stiffens the lungs and decreases breathing ability.

Common Symptoms of Pleural Effusions

Pleural effusion symptoms will vary in severity based on the damage to the lung. As the lung loses its ability to expand, symptoms such as cough and shortness of breath will worsen. In some cases, patients may not experience any symptoms. In other cases, an effusion could affect both lungs, collapse a lung or lead to infection.

Common Mesothelioma Pleural Effusion Symptoms
  • Dry cough
  • Shortness of breath
  • Fatigue
  • General discomfort
  • Pleurisy, or sharp chest pain with coughs or deep breaths
  • Orthopnea, or difficulty breathing when lying down
  • Rapid or shallow breathing
  • Persistent hiccups
  • Fever

Prognosis for Pleural Effusion Patients

Uncomplicated pleural effusions are not life-threatening, but pleural effusions associated with malignancies tend to have a worse prognosis. Malignant pleural effusions cause a significant number of cancer-related deaths, and median survival times are often less than 12 months in thoracic cancers.

Prognosis and survival for patients with malignant pleural effusions depend on several factors, including overall health, tumor cell type and characteristics of the pleural fluid.

Early diagnosis and treatment of a pleural effusion is the best way to improve prognosis. As therapy options advance for thoracic cancers such as mesothelioma, the survival rate and quality of life for patients with malignant pleural effusions should also improve.

How Are Pleural Effusions Diagnosed?

Doctors can diagnose a pleural effusion of over 300 milliliters, a little over a cup of fluid, through the use of an X-ray. A physical exam also helps your doctor identify signs and symptoms of the condition such as diminished breath sounds and reduced chest expansion.

Many types of disease can cause a pleural effusion, but doctors can examine the cells in the pleural fluid to identify an underlying cause such as asbestos-related cancer.

One method of collecting a sample of pleural fluid is a diagnostic thoracentesis. In this procedure, a doctor inserts a thin needle into the pleural space to extract liquid and then sends the sample to a lab for analysis.

In most cases, if there are cancer cells in the pleural fluid, the underlying cause is lung cancer, mesothelioma, breast cancer or lymphoma. However, thoracentesis alone is insufficient to diagnose mesothelioma, and your doctor will order a biopsy.

Treatment for Pleural Effusions

Most mesothelioma treatment options for pleural effusions are palliative and focus on reducing cancer symptoms and improving respiratory effort. Some options are more invasive and aim to prevent further occurrence of pleural effusion.

Thoracentesis: A doctor performs a thoracentesis by inserting a thin needle between the ribs and into the pleural space to extract a fluid sample. By temporarily reducing pressure from fluid around the lungs, the chest can expand more fully and breathing effort is improved.

Pleural Catheter: A small and flexible tube placed in the pleural space acts as a drain and allows patients to drain pleural fluid at home using vacuum-sealed bottles. This device can stay in the chest for several weeks until the pleural effusion resolves.

Pleurodesis: Doctors may perform pleurodesis to prevent recurring fluid buildup. During this procedure, doctors drain and surgically seal the pleural space. Pleurodesis is an invasive procedure that can be painful and may not entirely prevent future effusion.

Video-Assisted Thoracoscopic Surgery (VATS): VATS allows doctors to examine the pleural cavity and lungs for signs of asbestos-related diseases such as pleural thickening and plaques. A VATS procedure requires a thoracotomy, an incision between the ribs that allows access for a small fiber-optic camera. Doctors often perform a biopsy with VATS for increased precision.

Pleurectomy and Decortication: In cases of unexpandable lung, doctors may perform a more aggressive surgery with VATS to “free” the lung and allow for expansion. Pleurectomy and decortication involve removing the pleura and outer surface of the lungs. Doctors perform this surgery to reduce mesothelioma symptoms and remove tumor mass from the pleura.