Pleural Effusion On Chest X-ray

A pleural effusion is a common finding on chest X-ray which means there is fluid around the lung.  Pleural effusions can be caused by many conditions, ranging from benign to deadly.   They can be small and an incidental finding or large and symptomatic.

A pleural effusion is the accumulation of fluid between the layers of pleura that cover the lung.  There can normally be a small amount of pleural fluid.  

Symptoms of pleural effusion

A pleural effusion may or may not necessarily be the cause of your symptoms. Some people who have better health and more lung reserve may accumulate large amounts of fluid before they develop difficulty breathing. Others who are sicker may develop symptoms when the fluid accumulation is small.

What does a pleural effusion look like on chest X-ray?

The appearance depends on the technique of the chest X-ray and how the patient is positioned.  We can see fluid layering along the dependent part of the chest.  When large, they can push the heart to the opposite side.

What causes a pleural effusion?

There are many causes such as: infection, heart failure, cancer, inflammatory conditions such as lupus, cirrhosis, post heart surgery, pulmonary embolism (clots to the lungs) to name some.  

How do you tell the causes of pleural effusion apart?

There is often an underlying condition which is responsible for the effusion. Sometimes this is evident on a chest X-ray. When the heart is big and there is fluid in the lungs, then heart failure is the most likely diagnosis. When there is a mass in the lung, then the effusion is likely due to cancer. In some cases further testing will be needed.

Types of pleural effusion

The consistency of the fluid is important for identifying the cause. This unfortunately can only be done with sampling of the fluid. Fluid no matter if it is blood, pus or water will look the same on a chest X-ray.

More complex fluid in the pleural space is often associated with infections, inflammatory conditions, blood clots and cancer.   Simple fluid can be seen with cirrhosis, heart failure and kidney conditions.

Is a pleural effusion dangerous?

It depends on the underlying cause.  Some conditions like blood clots in the lungs, infections and cancer can be life threatening.  Large effusions can push structures like the heart and cause problems with breathing.

What should be done next when a pleural effusion is found on chest X-ray?

Since a pleural effusion can have many causes, it is important for your doctor to direct further testing and diagnosis in conjunction with your history. For example, if you have heart failure then the effusion can be treated with medications. If you have a smoking history with an effusion, then further testing may include imaging with cat scan and possible sampling of the fluid to exclude cancer. If you have liver or kidney conditions, then the effusion may simply be a result.

If a pleural effusion is identified on a chest X-ray, your doctor may order a cat scan to further evaluate. Often a cat scan will show findings that a chest X-ray will not. This is especially true if a cancer, clot or lung infection is suspected. If the diagnosis is still not apparent, then a thoracentesis may be performed which involves directly sampling the fluid. This can also help with diagnosis.

Pleural effusion treatment

In many cases, the treatment of an effusion consists of treating the underlying condition.  This can be antibiotics for an infection and chemotherapy, radiation or surgery for cancer.

If the effusion is symptomatic and large, then the fluid can be removed (thoracentesis) for symptom relief and further testing. This involves placing a needle into the pleural space or covering of the lung and removing the fluid.

Pleural effusion on a chest X-ray: summary

Pleural effusions on chest X-rays can have many causes.  Often more clinical information, further imaging and testing of the fluid can help narrow the causes.  Treatment often consists of treating the underlying condition and removing the fluid.