What is ascites?

Ascites (pronounced aye-site-eez) is the medical name for a build up of fluid in the tummy (abdomen). If the ascites is caused by cancer it can also be called malignant ascites. Unfortunately having ascites can mean you have advanced cancer.

Your abdomen contains many organs including your:

• stomach
• bowel
• pancreas
• liver
• spleen
• kidneys

They are all in the peritoneal space. This is lined with a sheet of tissue called the peritoneum. The peritoneum is made up of 2 layers. One lines the wall of the peritoneal space. The other covers the organs.

The layers produce a small amount of fluid. This lets your organs slide around slightly as you move. Sometimes the fluid builds up between the 2 layers, which makes your abdomen swell. This can be very uncomfortable. The fluid build up is called ascites. 

The diagram below shows ascites in a woman.

The causes of ascites

Cancers that can cause ascites include:

• ovarian cancer

• womb cancer

• bowel cancer

• stomach cancer

• pancreatic cancer

• liver cancer

These organs are all in your abdomen.

Ascites can also be caused by mesothelioma in the peritoneum. And by cancers that start outside of your abdomen including:

• lung cancer

• breast cancer

Fluid can build up in your abdomen when:

• cancer cells irritate the lining of your abdomen and make it produce too much fluid

• lymph glands in your abdomen get blocked - this means the fluid can’t drain properly

• cancer has spread to your liver - this raises the pressure in nearby blood vessels so fluid gets forced out of them

• your liver can’t make enough blood proteins so fluid leaks out of your veins into the abdomen

Other conditions that can cause ascites include:

• liver disease
• heart disease
• pancreatitis 
• some infections including tuberculosis

It can also be a side effect of some cancer drugs.

What are the symptoms of ascites?

Ascites can make your tummy feel tight and very uncomfortable. It often develops over a few weeks. But it might happen over a few days.

It puts pressure on the organs in your abdomen. It can also put pressure on your diaphragm which is at the top of your abdomen. This can affect your lungs.

The pressure may lead to:

• your clothes feeling tighter - you may need a bigger belt size

• bloating

• abdominal pain

• back pain

• difficulty sitting comfortably and moving around

• loss of appetite

• indigestion

• constipation

• needing to pass urine often

• breathlessness

• tiredness and weakness (fatigue)

• feeling or being sick

You may not have all of these symptoms. But it is important to speak to your doctor or specialist nurse (CNS) if you have any of them.

Tests for ascites

Your doctor examines you and asks about your symptoms. They may ask you to have some tests to find the cause of the swelling. These might include:

• an ultrasound scan

• blood tests to check your general health and how well your liver and kidneys are working

• a CT scan

• having a sample of the fluid taken from your abdomen (paracentesis) to check for cancer cells or infection

Paracentesis

Your doctor puts local anaesthetic in your skin to numb the area. Then they put a needle into your abdomen to take a sample of fluid. This can be uncomfortable but it isn’t usually painful. They may use an ultrasound scan to guide them. 

They draw out some of the fluid and send it to the laboratory to check for cancer cells.

Normally they leave a tube in your abdomen for a few hours so the rest of the fluid can drain out.