Overview
Ascites occurs when excess fluid builds up in your belly area, called the abdomen. The fluid collects in the peritoneal cavity, which is the space around your abdominal organs. This buildup can make your belly look swollen or feel tight. As more fluid accumulates, you might feel discomfort or pain.
Ascites most often happens when someone has serious liver disease, such as cirrhosis. It also can be linked to other conditions, including heart failure, certain cancers and pancreatic disease. The best treatment for ascites depends on what causes the fluid to build up.
Types
Healthcare professionals often classify ascites based on the cause of the fluid buildup. Ascites also may be described by how much fluid is present and how the condition behaves over time.
Based on the amount of fluid, ascites is commonly grouped into these grades:
- Grade 1, mild ascites. A small amount of fluid that may not be noticeable on a physical exam and is sometimes found only on imaging tests.
- Grade 2, moderate ascites. Fluid buildup that causes visible swelling of the abdomen.
- Grade 3, large or tense ascites. A large amount of fluid that makes the abdomen very swollen and causes discomfort.
Ascites also can be described by how it responds to treatment. In many people, fluid buildup can be managed with medicines and dietary changes. In others, ascites continues to worsen or returns despite treatment, and frequent removal is needed by physically draining the fluid. This is called refractory ascites and usually means the underlying disease is more serious.
Symptoms
Mild ascites may not cause any symptoms and can be easy to miss. As more fluid builds up and the ascites progresses to moderate or severe, your belly can look swollen or feel heavy or tight. You also might notice weight gain or a larger waistline, even without changes in eating habits.
Early ascites can feel like bloating, but the swelling usually lasts and may get worse over time. While bloating often comes and goes, ascites typically does not get better without treatment.
Ascites can make it harder to breathe, especially if a lot of fluid builds up. As your belly fills with fluid, it pushes up on the diaphragm, the muscle that helps your lungs expand. Ascites is different from pleural effusion, which is when fluid collects around the lungs and can make breathing harder.
Symptoms of ascites can develop over days or even months, depending on the cause. Some people have a swollen belly without pain. Others feel pressure, fullness or discomfort. If enough fluid collects, symptoms may include:
- Shortness of breath or feeling winded.
- Feeling full after small meals.
- Belly pain, especially when large amounts of fluid collect.
- Swelling in the legs or ankles, called edema.
- Rapid weight gain.
- Fever or confusion, which can be signs of infection.
Causes
Ascites can happen for different reasons, but it most often occurs because of portal hypertension caused by cirrhosis. This condition is a late stage of chronic liver disease, when scarring changes the liver's structure.
Cirrhosis can develop from many causes, including long-term alcohol use, viral hepatitis and fatty liver disease, also called metabolic dysfunction-associated steatotic liver disease (MASLD). As the scarring gets worse, blood cannot flow through the liver as easily. This increases pressure in the portal vein system, which carries blood to the liver.
This higher pressure, along with changes that cause the body to keep more salt and water, can make fluid build up in the belly. In people with cirrhosis, developing ascites typically means the liver disease has reached an advanced stage.
Liver disease is not the only reason someone might get ascites. Some other possible causes include:
- Cancer, sometimes called malignant ascites. This can include ovarian, breast, colon, and liver cancers, among others.
- Heart failure.
- Infections of the lining of the abdomen, such as tuberculosis.
- Low blood protein levels from conditions such as nephrotic syndrome, protein-losing enteropathy or severe malnutrition.
- Pancreatic disease, such as pancreatitis or injury to the pancreas, which can lead to fluid buildup in the abdomen.
These conditions can cause ascites in different ways. For example, cancer may affect the lining of the abdomen or block typical fluid absorption. Low blood protein levels also can make it easier for fluid to collect in the abdomen.
Sometimes, more than one condition can cause ascites. Because treatment depends on the cause, your care team will try to find out what is making the fluid build up.
Risk factors
Risk factors for ascites are generally those that increase your likelihood of developing the underlying conditions that cause it. These include:
- Factors that raise the risk of liver disease and cirrhosis.
- Long-term alcohol use. Drinking large amounts of alcohol over time can damage the liver, leading to cirrhosis.
- Chronic viral hepatitis. Long-term infection with hepatitis B or hepatitis C can damage your liver and raise the risk of cirrhosis.
- Obesity. Being obese is linked to a higher risk of metabolic dysfunction-associated steatotic liver disease (MASLD), which can progress to cirrhosis.
- Factors that raise the risk of cancer. Depending on the type of cancer, risk factors can include genetics, smoking, obesity, certain infections and environmental exposures.
- Factors that raise the risk of heart failure. These can include high blood pressure, coronary artery disease, diabetes and obesity.
Having more than one risk factor or underlying condition can further increase the likelihood of developing ascites. Your healthcare team can talk with you about your personal risk based on your health history.
Complications
Ascites can cause complications, especially when a large amount of fluid builds up. Some complications need prompt medical care. Potential complications include:
- Infection of the abdominal fluid, called spontaneous bacterial peritonitis (SBP). Sometimes, the fluid from ascites can get infected. Spontaneous bacterial peritonitis is a serious condition that can lead to fever, belly pain, kidney failure or confusion. It needs urgent treatment with antibiotics.
- Breathing problems. When there is a lot of fluid, it can push up on the diaphragm, the muscle that helps you breathe. This pressure can make breathing harder.
- Hernias. If fluid keeps building up, it can weaken the muscles in your belly. This can cause hernias, such as umbilical or inguinal hernias, which can be painful or uncomfortable.
- Malnutrition and weakness. Ascites can make you feel full quickly, lower your appetite and make it hard to eat enough. Over time, this can lead to poor nutrition.
Because complications can develop quickly, it's important to stay in close contact with your healthcare team and report any new or worsening symptoms.
Prevention
Ascites cannot always be prevented. It most often develops as a complication of serious liver disease or other medical conditions. However, steps to protect your liver and manage underlying health issues may lower the risk of developing ascites or slow its progression.
Here are some ways you can lower your risk:
- Manage liver disease early. Getting treatment for conditions such as viral hepatitis or fatty liver disease can lower your risk of liver-related issues, including ascites.
- Get vaccinated against hepatitis A and B. The hepatitis B vaccine helps prevent chronic liver disease that can lead to cirrhosis and ascites, while the hepatitis A vaccine helps protect overall liver health. There is currently no vaccine for hepatitis C.
- Avoid alcohol if you have liver disease. Alcohol can worsen liver damage and increase the risk of cirrhosis.
- Keep a healthy weight. Being overweight increases the chance of fatty liver disease, which can lead to cirrhosis and ascites over time.
- Manage other medical conditions. Treating conditions such as heart failure may help reduce fluid buildup in the body.
- Reduce salt intake. Eating less salt can help your body avoid holding on to extra fluid. If you are at risk of ascites, following a low-salt diet may help slow down or reduce fluid buildup.
If you already have liver disease or another condition linked to ascites, working closely with your healthcare team can help reduce the risk of complications.