Fluid on the lungs or in the abdomen

Cancer can cause fluid to collect around the lungs or in the tummy (abdomen). This includes:

  • fluid on the lung which is called pleural effusion
  • fluid collecting inside the lung which is called pulmonary oedema
  • fluid build up in the tummy area (abdomen) which is called ascites

Fluid on the lungs

Two sheets of tissue protect the lungs. They are called pleural membranes (or pleura). The space inbetween the pleura is called the pleural space.

Cancer cells can inflame the pleura and this makes fluid. The fluid builds up in the pleural space and is called a pleural effusion. The fluid stops your lungs from expanding fully. So you have to take shallower breaths and make more effort to breathe.

Diagram showing the pleura and pleural space
Diagram showing a build up of fluid in the lining of the lungs (pleural effusion)


Your doctor can put in a tube for a short time to drain the fluid and help you breathe more easily.

You can also have treatment to try to stop the fluid from building up again. This is called pleurodesis.

Pulmonary oedema 

If your doctor talks about fluid on the lung they might mean pleural effusion. Or they might mean you have fluid actually collecting inside the lung. This is called pulmonary oedema. It is not usually possible to have this fluid drained. Pulmonary oedema is usually caused by heart problems. You might need treatment to stop the fluid collecting. 

Fluid in the abdomen (ascites)

Cancer can also make fluid build up in the tummy area (abdomen). This fluid is called ascites.

Cancer cells may attach themselves to the lining of the abdomen and irritate it. This makes the abdominal lining make fluid, which collects in the abdomen.

Ascites is quite common in women with ovarian cancer. People with secondary liver cancer may also get ascites because of congestion in the liver making pressure build up in the circulation. The pressure makes fluid leak out from the bloodstream and lymphatic system and collect in the abdomen.

Diagram showing fluid in the abdomen

If there is a lot of fluid, your abdomen can become quite swollen. So it pushes upwards, against your stomach and the sheet of muscle that separates your abdomen from your chest (the diaphragm).

The increased pressure on your diaphragm makes it harder for your lungs to expand when you breathe in. This can make you breathless.

Last reviewed: 
21 Nov 2019
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