Pleural Effusion

X-ray depicting a pleural effusion, with the white area on the left side of the image (right side of the patient) indicating fluid in the chest.

What is a pleural effusion?

A pleural effusion occurs when fluid builds up in the space between the lungs and the chest wall, called the pleural space.

Our bodies closely regulate the amount of pleural fluid we have, and in healthy individuals there is only a small volume of fluid in the pleural. However, conditions that result in increased production and/or impaired reabsorption of pleural fluid can lead to its abnormal accumulation.

This can cause symptoms like shortness of breath, chest pain and coughing. Pleural effusion can be caused by several conditions, such as heart problems, bacterial infections or cancer.

What are the symptoms of pleural effusions?

The symptoms of pleural effusion can vary depending on the amount of fluid present and the underlying cause. Common symptoms include:

• Shortness of breath, particularly with physical activity or exertion
• Chest pain, often sharp and worsened by deep breathing or coughing
• A persistent cough
• Difficulty lying flat or a preference for sitting upright to breathe more easily

It is important to seek medical attention if you experience these signs, especially if they worsen over time.In some cases, particularly if the effusion is small or develops slowly, there may be no noticeable symptoms.

When should you see a doctor?

You should seek medical attention if you experience persistent symptoms that may indicate pleural effusion, such as difficulty breathing, chest pain or a persistent cough. These symptoms could signal an underlying condition requiring treatment, such as infection, heart failure or lung disease. Delaying evaluation could lead to complications or worsening of the condition.

If you notice severe shortness of breath, worsening chest pain or significant difficulty breathing while lying down, you should see a doctor immediately. These could be signs of a large or rapidly developing pleural effusion, which may require urgent intervention to prevent serious health risks. Prompt diagnosis and treatment are crucial to manage the condition effectively.

What are the potential complications of pleural effusions?

If left untreated, a pleural effusion can lead to serious complications. These may include:

• Infection: Bacterial infection in the pleural space requires early drainage and antibiotics.
• Breathing problems: Persistent fluid build-up may result in significant shortness of breath and reduced exercise tolerance.
• Underlying disease progression: Delay in treating the cause of the effusion, such as cancer or heart failure, can worsen the primary condition and reduce treatment effectiveness.
• Pleural thickening: Inflammation or repeated effusions can cause the pleura to scar and thicken, restricting lung movement.

How are pleural effusions prevented?

As there are many different causes of pleural effusions, there is no definitive way to prevent them.
It is recommended to maintain a healthy lifestyle, which includes:

• A balanced diet
• Regular exercise
• Managing underlying conditions: Proper treatment and management of chronic illnesses such as heart failure , kidney disease or liver disease can lower the risk.
• Avoiding exposure to harmful substances: Minimise exposure to asbestos, chemicals or pollutants that could damage the lungs or pleura.
• Quitting or avoiding tobacco smoking: Smoking increases the risk of lung diseases and conditions that may lead to pleural effusion.
• Regular medical check-ups and health screenings according to recommended guidelines: Early detection of conditions such as cancer or autoimmune diseases can allow timely treatment and reduce the likelihood of pleural effusion.

This will reduce the risk of conditions like heart or kidney disease and potentially detect cancer in its early stages.

What causes pleural effusions?

Pleural effusion occurs when fluid builds up abnormally in the pleural space.
There are many conditions (over 50 different diseases) that can lead to a pleural effusion. This includes:

• Heart failure: The most common cause, leading to pleural fluid accumulation due to impaired heart function.
• Pneumonia or tuberculosis: Lung infections can cause inflammation, resulting in accumulation of fluid into the pleural space.
• Cancer: Certain cancers, particularly lung or breast cancer , can cause pleural effusion either directly or by spreading to the pleura.
• Liver or kidney disease: Reduced protein levels or fluid overload in these conditions can lead to pleural effusion.
• Pulmonary embolism: A blood clot in the lungs can trigger fluid build-up in the pleural space.
• Autoimmune diseases: Conditions such as rheumatoid arthritis or lupus can cause pleural inflammation, leading to fluid accumulation.

Pleural effusions can also develop after heart surgery or injury to the chest wall such as a rib fracture.

What are the risk factors for pleural effusions?

Certain factors can increase the likelihood of developing pleural effusion, including:

• Chronic illnesses: Conditions such as heart failure, liver disease or kidney disease can raise the risk.
• Infections: Respiratory infections or tuberculosis can increase the likelihood of pleural effusion.
• Smoking: Smoking is linked to lung damage and diseases that may result in pleural effusion.
• Asbestos exposure: Exposure to asbestos raises the risk of pleural diseases, including pleural effusion.
• Cancer history: A personal or family history of cancer, especially lung or breast cancer, increases the risk.
• Chest trauma or surgery: Injuries or surgical procedures involving the chest can make fluid accumulation more likely.
  

How are pleural effusions diagnosed?

Diagnosing pleural effusion typically involves a combination of medical history taking, physical examination and diagnostic tests to confirm the presence of fluid and determine its cause.

• Medical history taking and physical examination: A doctor will ask about symptoms such as shortness of breath or chest pain and review any underlying health conditions. During the examination, they may listen to the chest with a stethoscope for reduced breath sounds or dullness when tapping the chest wall.
• Imaging tests: Chest X-rays, ultrasound and computed tomography (CT) scans are commonly used to detect fluid in the pleural space. Ultrasound and CT scans of the chest may also reveal signs of infection or features of cancer, which help to narrow down the possible causes.
• Blood tests: These may be performed to check for infections, inflammatory conditions or other medical issues contributing to pleural effusion.
• Pleural fluid and pleural tissue analysis: Sometimes, if the aforementioned tests are insufficient to make a diagnosis, further evaluation may be required.

This usually involves obtaining a sample of pleural fluid or pleural tissue for analysis.

Pleural fluid analysis

Pleural aspiration

A procedure called a pleural aspiration is recommended to obtain samples of pleural fluid for analysis. It can be performed in an outpatient setting, with the injection of local anaesthetic medication to numb the skin and surrounding tissues before a small needle is passed into the pleural space to remove the pleural fluid.

If there is a large amount of fluid in the chest causing symptoms such as shortness of breath, more fluid can be removed which may help to improve the symptoms.

Chest drain
An alternative is the insertion of a chest drain, which may be preferred if there is suspicion of an active air leak from the lungs, or infection of the pleural space.

This is a slightly larger flexible tube that is also passed through the chest wall into the pleural space, under local anaesthesia. However, patients will need to be hospitalised after insertion of a chest drain.

Pleural tissue analysis
Your doctor may also recommend obtaining tissue from the pleura for analysis – particularly in cases where the pleural fluid analysis is inconclusive, or if there is suspicion of conditions like cancer or tuberculosis.
The procedure to obtain pleural tissue is called a pleural biopsy.

Medical thoracoscopy
There are several ways of obtaining pleural biopsies. One is with a procedure called a medical thoracoscopy.

A thoracoscopy involves passing a small camera into the pleural space under local anaesthesia and moderate sedation.

This allows us to remove pleural fluid, inspect the pleura for any abnormalities and perform biopsies of the pleura under direct vision.

In some cases, thoracoscopy may be performed as an outpatient procedure.

Image-guided pleural biopsy
The other option is an image-guided pleural biopsy, where imaging tools such as CT or ultrasound are used – to identify abnormal areas of the pleura, and guide a small needle through the chest wall to take biopsies from those areas.
It is performed under local anaesthesia and generally does not require sedation.

Deciding which procedure is more suitable depends on several factors. For example, in patients who may not be fit for a thoracoscopy because the risk of sedation may be too prohibitive, an image-guided pleural biopsy may be recommended instead.

How are pleural effusions treated?

Treatment for pleural effusion focuses on relieving symptoms, removing the excess fluid and addressing the underlying cause.
The approach depends on the severity of the effusion and its root cause, and may include:

• Draining the fluid: Procedures like pleural aspirations or chest drain insertions to remove fluid from the pleural space can be performed. This can relieve symptoms such as shortness of breath and obtain fluid samples for further analysis.
• Medications: If the effusion is caused by an infection, antibiotics will be prescribed. If it is a result of heart or kidney dysfunction, medications can be started to help reduce fluid build-up in the pleural space. Anti-inflammatory drugs may be used for autoimmune conditions, and anti-cancer medications (such as chemotherapy) for pleural effusions due to cancer.

Not all causes of pleural effusions require treatment. Some conditions such as pleural effusions that occur after heart surgery often resolve spontaneously with time.

How are recurrent pleural effusions managed?

Pleural effusions may recur depending on the underlying cause. For example, pleural effusions from cancer (also known as malignant pleural effusions) may reaccumulate, and if large enough, lead to symptoms.

Repeated pleural aspirations
Repeated pleural aspirations, which remove pleural fluid each time it builds up, can be performed. The disadvantage of this option is that it only provides temporary relief and needs to be repeated once significant amounts of fluid build-up.

There are more definitive ways of managing symptoms from recurrent pleural effusions, including talc pleurodesis and indwelling pleural catheters (IPC). Whether talc or IPC is recommended varies for each individual – often taking into consideration the priorities and values of both patient and caregivers.

Talc pleurodesis
This involves hospitalisation and insertion of a chest drain to drain out the pleural fluid. If the lung re-expands well after fluid drainage, a medication called talc is instilled through the chest drain and into the pleural space.

Talc acts like a mild irritant which helps to ‘stick’ the lung to the chest wall. If successful (about 70% of the time), this closes the pleural space and reduces the risk of fluid reaccumulating in the future.

Indwelling pleural catheter
This involves the insertion of a semi-permanent chest drain called an indwelling pleural catheter (IPC).

The IPC is a soft flexible tube inserted into the pleural space, and is meant to remain in place as long as needed (i.e., months to years) to allow pleural fluid to be removed whenever it builds up.

The draining of pleural fluid can be performed via the IPC by patients and caregivers in their homes.

Medications
Finally, there are also medications that can be effective in managing symptoms resulting from pleural effusions, such as opioids which relieve the sensation of breathlessness.

Can pleural effusion go away on its own?
In some cases, small pleural effusions may resolve without treatment, especially if the underlying cause is mild or temporary. However, larger or persistent effusions typically require medical intervention to prevent complications. It is important to consult a doctor for proper evaluation and management.

Is pleural effusion a serious condition?
Pleural effusion can range from mild to severe, depending on the amount of fluid and the underlying cause. While some cases are manageable with treatment, others may indicate serious conditions such as cancer or infections. Prompt diagnosis and treatment are crucial to avoid complications.

Can pleural effusion return after treatment?
Yes, pleural effusion can recur if the underlying cause is not fully addressed or if it is a result of chronic conditions such as cancer or heart failure. In recurrent cases, procedures like pleurodesis or an indwelling catheter may help manage the condition effectively.

References 

Roberts ME, Rahman NM, Maskell NA , et al. British Thoracic Society Guideline for pleural disease 2023;78(suppl 3):1-42.