Ascites is the build-up of fluid in the abdomen.

This fluid buildup causes swelling that usually develops over a few weeks, although it can also happen in just a few days.

Ascites is very uncomfortable and causes nausea, tiredness, breathlessness, and a feeling of being full.

Liver disease is the most common cause of ascites. Other causes typically include cancer and heart failure.

In this article, we will explore the causes of ascites, as well as the symptoms and treatment options.

Fast facts about ascites

  • Ascites is a symptom of another underlying cause.
  • Abdominal swelling and associated weight gain are typical symptoms of ascites.
  • Prognosis and outlook of ascites depend on the underlying condition.
  • Assessment of the progress of ascites may be made by regularly measuring the abdominal girth and by monitoring weight.

Ascites occurs when fluid accumulates in the abdomen. This buildup occurs between two membrane layers that together make up the peritoneum, a smooth sac that contains the body's organs. It is usual to have a small amount of fluid in the peritoneum cavity.

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Ascites refers to abdominal pain and swelling as the result of fluid buildup.

Many underlying diseases can be responsible for causing ascites, including tuberculosis, kidney disease, pancreatitis, and an underactive thyroid. However, the primary causes of ascites are heart failure, cirrhosis, and cancer.

Ascites may develop if cancer affects the:

  • peritoneum
  • liver
  • lymphatic system
  • ovaries
  • breast
  • bowel
  • stomach
  • pancreas
  • lung
  • womb

Ascites is often painful and typically causes a person to feel:

  • nauseated
  • less hungry than usual
  • tired
  • breathless
  • urinary urgency and constipation

Fluid retention causes pressure on other internal organs, which often results in a person experiencing discomfort. Ascites may also cause bloating, abdominal and back pain, and lead to a person having difficulty sitting and moving.

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Liver disease is the leading cause of ascites. However, many serious conditions can lead to the buildup of fluids in the abdomen.

If cirrhosis has caused ascites, an individual may benefit from reducing salt and taking water tablets (diuretics).

Water tablets cause urine to pass more frequently and can prevent further fluid retention.

While this is an effective approach in many situations, some types of ascites are resistant to diuretics.

In severe cases, a liver transplant may be the best option. Other treatments include:

Paracentesis

In resistant cases, or if there is a significant amount of excess fluid, paracentesis can be an effective management technique. Paracentesis involves a doctor inserting a needle into the abdomen and draining off the excess liquid.

The aim of paracentesis is to relieve abdominal pressure, so the person feels less discomfort. In some instances, a person's abdomen might contain about 5 liters of fluid, but in some extreme cases of ascites, doctors have drained more than 10 liters of fluid from the abdomen.

Shunts

When ascites is caused by cancer, doctors may use a shunt (tube) to move the fluid from the abdomen into the bloodstream.

A doctor inserts a needle into a vein in the neck and places a shunt along the chest wall. The shunt connects the abdominal cavity to the neck, where it enters the vein. The fluid then moves along the tube into the bloodstream.

Chemotherapy

Chemotherapy can help to shrink or control cancer. It can be administered through a tube in the abdomen, which can sometimes stop fluid building up. Unfortunately, there is not much evidence to suggest that this works well.

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Ascites has a range of gastrointestinal effects, including nausea, discomfort, and lack of appetite.

The underlying conditions that cause ascites are often serious illnesses linked to reduced life expectancy.

The first diagnostic method is usually an abdominal examination. A doctor will look at the person's abdomen while they are lying down and standing up. The abdominal shape will usually indicate whether or not there is a buildup of fluid.

Assessment of the progress of ascites may be made by regularly measuring the abdominal girth and by monitoring weight.

These measurements are helpful because fluctuations in weight due to changes in the abdominal fluid are much faster than weight fluctuations linked to body fat.

Once fluid buildup is confirmed, further tests may be needed to pinpoint the cause. These include:

  • Blood tests: These can usually assess liver and kidney function. If cirrhosis is confirmed, further tests will be required to clarify the cause and will include antibody tests for hepatitis B or C.
  • Fluid sample analysis: A sample of abdominal fluid may show cancer cells are present or that there is an infection. Doctors remove fluid from the abdomen with a syringe and send it to a laboratory for analysis.
  • Abdominal ultrasound: This is helpful for identifying underlying causes of ascites. It can show if a person has cancer or if cancer has spread to the liver.

If an ultrasound investigation does not reveal a cause of ascites, then doctors may recommend an MRI (magnetic resonance imaging) scan.

X-rays are also excellent diagnostic imaging tools. They can confirm buildup of fluid in the lungs, cancer that has spread to the lungs, or heart failure.

Prognosis and outlook of ascites depend on the underlying condition. Symptoms can be managed and reduced, but it is the treatment of the cause of ascites that determines the outcome.

There is currently no satisfactory treatment for people who have cirrhosis as well as a form of ascites that is resistant to diuretics.

Paracentesis and shunts without a liver transplant may improve a person's quality of life but are not thought to improve long-term life expectancy significantly.