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Ascites is an abnormal buildup of fluid in the abdomen, specifically the peritoneal cavity. It occurs when the body makes more fluid than it can remove. Ascites can occur with cancer and other conditions. When ascites is due to cancer, or if the fluid in the abdomen contains cancer cells, it is often called malignant ascites or malignant peritoneal effusion.


People with cancer can develop ascites for different reasons. It may be caused by:

  • cancer cells that spread to and irritate the thin membrane that lines the inner wall of the abdomen (called the peritoneum)
  • tumours that block the lymphatic system so lymph fluid can’t flow properly
  • the liver not making enough protein (albumin), which may upset the body’s fluid balance
  • cancer cells that block blood flow through the liver

Ascites develops most often with ovarian, uterine (endometrial), cervical, colorectal, stomach (gastric), pancreatic or primary liver cancers. Cancer that spreads to the liver can also cause ascites.


Symptoms of ascites can vary depending on their cause and other factors. Symptoms of ascites include:

  • swelling of the abdomen
  • feeling of bloating
  • abdominal discomfort or pain
  • fatigue
  • shortness of breath
  • weight gain
  • nausea
  • vomiting
  • indigestion
  • loss of appetite, or anorexia
  • feeling satisfied after eating a small amount (early satiety)
  • constipation
  • ankle or leg swelling
  • the umbilicus, or belly button, sticks out or flattens

If symptoms get worse or don’t go away, report them to your doctor or healthcare team without waiting for your next scheduled appointment.


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

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

Sometimes a paracentesis, or abdominal tap, is done to find out if the fluid in the abdomen contains cancer cells.

Find out more about these tests and procedures.

Managing ascites

Once the cause of ascites is known, your healthcare team can suggest ways to manage it. In some cases, medicines called diuretics are given to help the body get rid of extra fluids. But these drugs are usually not very effective in treating ascites caused by cancer.

The following measures may be used to manage malignant ascites. They relieve the symptoms of ascites or treat the cancer that is causing them.


Paracentesis is a procedure used to drain fluid from the abdomen and relieve swelling. The doctor drains the fluid by putting a needle or small tube (called a catheter) through the skin and abdominal wall into the peritoneal cavity. A local anaesthetic numbs the area. The doctor may use an ultrasound to guide the needle to the area where there is the most fluid. Paracentesis can be repeated if the fluid builds up again.

You may be given intravenous fluids at the same time as the paracentesis. This is because your blood pressure may drop if too much fluid drains too quickly.


Chemotherapy may be given to treat the cancer causing ascites or cancer cells in the fluid. The specific drugs used will depend on the type of cancer causing the fluid buildup.

Systemic chemotherapy circulates throughout the body. It is usually given intravenously, but it is sometimes given as pills.

Intraperitoneal chemotherapy gives drugs directly into the abdominal cavity through a small tube, or catheter. This means that the drug comes in direct contact with the cancer cells in the fluid. Intraperitoneal chemotherapy is not commonly used. It works best if there is a small number of cancer cells in the abdomen.

peritoneal cavity

The space between the parietal peritoneum (the membrane that lines the walls of the abdomen and pelvis) and the visceral peritoneum (the membrane that covers and supports most of the abdominal organs).

lymphatic system

The group of tissues and organs that produce and store cells that fight infection and diseases.

The lymphatic system includes the adenoids, tonsils, spleen, thymus, lymph nodes, lymph vessels and bone marrow.

Also called the lymph system.


Dr Senthil Muthuswamy Pancreatic tumours in a dish

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