Pleural Effusion

Reviewed/Revised Feb 2023
VIEW PROFESSIONAL VERSION
Get the full details

Two layers of thin membrane, called the pleura, cover your lungs. The two membranes normally touch each other. But sometimes the space between the membranes, called the pleural space, fills up with air or fluid.

Fluid in the pleural space is called pleural effusion. Air in the pleural space is called pneumothorax.

What is a pleural effusion?

A pleural effusion is a build-up of fluid in your pleural space.

  • A pleural effusion may be caused by many different problems such as an infection, tumor, or injury

  • The fluid may be watery or have blood or pus in it

  • You may have shortness of breath and chest pain, especially when you breathe deeply or cough

  • Doctors can see a pleural effusion on a chest x-ray or ultrasound

  • Doctors will treat the problem that’s causing the pleural effusion and may drain the fluid with a needle

What causes a pleural effusion?

Many different problems can cause a pleural effusion:

What are the symptoms of a pleural effusion?

If you have a pleural effusion, you may not have any symptoms, or you may have:

  • Shortness of breath

  • Chest pain, especially when you breathe deeply or cough

  • Sometimes, pain in your upper belly, neck, or shoulder

How can doctors tell if I have a pleural effusion?

To tell if you have a pleural effusion, doctors will do:

Once a pleural effusion is found, doctors may do more tests and procedures:

How do doctors treat a pleural effusion?

Doctors will treat the problem that’s causing your pleural effusion. For example, if you have a lung infection, you may get antibiotics.

If there's only a little bit of fluid, doctors may:

  • Wait to see if the fluid goes away on its own

If there's a lot of fluid, or if the fluid makes it hard to breathe, doctors may:

  • Drain the fluid out with a needle

They put the needle or tube in through the side of your chest between two ribs. If fluid builds up again after it’s drained, sometimes they leave a small tube in your chest to keep the fluid draining.

If the fluid was caused by a cancer, doctors may put a medicine or other substance in through the tube (pleurodesis). The medicine irritates the pleura and causes them to scar together so that fluid can't build up.

quizzes_lightbulb_red
Test your KnowledgeTake a Quiz!
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID