Fluid buildup in the abdomen (ascites)

Fluid buildup in the abdomen is called ascites. Normally, there is a very small amount of fluid in the peritoneal cavity. This fluid lubricates the surfaces of the organs in the cavity and prevents friction between the organs and the cavity lining. Ascites is when the peritoneal cavity makes more fluid than it can remove. It can happen because of cancer and other conditions.

If ascites is a side effect of cancer or there are cancer cells in the fluid, it is often called malignant ascites or malignant peritoneal effusion.

Malignant ascites is caused by cancer cells that spread to and irritate the lining of the abdomen (called the peritoneum) . The cancer cells can also block or change the flow of lymph fluid in the peritoneal cavity or block blood flow through the liver.

The following cancers are more likely to cause ascites:

• ovarian
• uterine
• cervical
• colorectal
• stomach
• bladder
• pancreatic
• liver
• breast

Cancer that starts in one part of the body and spreads to the liver (liver metastases) can also cause ascites.

Other conditions can cause fluid to build up in the abdomen. These include:

• cirrhosis – this can lead to the liver not making enough protein (albumin) and disturb the body’s fluid balance
• infection of the peritoneum (peritonitis)

Signs and symptoms of ascites can vary depending on their cause and other factors. They include:

• a swollen or bloated abdomen
• pain in the back or abdomen
• fatigue
• shortness of breath
• weight gain
• nausea and vomiting
• indigestion
• loss of appetite or feeling full after eating a small amount
• constipation
• a swollen ankle or leg
• changes to the belly button

Tell your doctor or healthcare team about any symptoms you have. The sooner you tell them of any symptoms, the sooner they can suggest ways to help manage them.

Your healthcare team will try to find the cause of ascites. You may need to have the following tests:

• a physical exam
• an abdominal x-ray
• an abdominal ultrasound or a CT scan

Sometimes fluid is removed from the abdomen with a long, hollow needle. This procedure is called a paracentesis. The fluid may be sent to the lab to see if it contains cancer cells. Lab tests can also check if ascites is caused by a non-cancerous condition. Find out more about a paracentesis.

Once your healthcare team knows the cause of ascites, they may suggest a paracentesis and other ways to manage it, including:

• leaving a flexible tube (called a tunnelled peritoneal drainage catheter) in the abdomen after a paracentesis, so the fluid can be drained regularly at home
• infusing albumin intravenously (through an IV) after a paracentesis to help slow down the buildup of fluid
• reducing the amount of salt you eat and the amount of fluids you drink
• taking medicines to help your body get rid of extra fluids (called diuretics)
• surgery to place a shunt that redirects fluid from one place to another so that it doesn’t build up

If cancer is causing the ascites, treating the cancer can also help manage it.