Ascites is the accumulation of protein-containing (ascitic) fluid in the abdominal cavity.
- Many disorders can cause ascites, but cirrhosis is the most common.
- If large amounts of fluid accumulate, the abdomen becomes very large, sometimes making people lose their appetite and feel short of breath.
- Analysis of the fluid can help determine the cause.
- Usually, bed rest, a low-salt diet, and diuretics help eliminate excess fluid.
Ascites tends to occur in long-standing (chronic) rather than in short-lived (acute) disorders. It occurs most commonly in cirrhosis (severe scarring of the liver), especially in cirrhosis caused by alcoholism or viral hepatitis. It may occur in other liver disorders, such as severe alcoholic hepatitis without cirrhosis, chronic hepatitis, and obstruction of the hepatic vein (Budd-Chiari syndrome). Ascites can also occur in disorders unrelated to the liver, such as cancer, heart failure, kidney failure, inflammation of the pancreas (pancreatitis), and tuberculosis affecting the lining of the abdominal cavity.
In people with a liver disorder, ascitic fluid leaks from the surface of the liver and intestine. A combination of factors is responsible. They include portal hypertension, decreased ability of the blood vessels to retain fluid, fluid retention by the kidneys, and alterations in various hormones and chemicals that regulate bodily fluids.
Small amounts of fluid in the abdominal cavity usually produce no symptoms, but massive amounts may cause abdominal swelling (distention) and discomfort. Pressure on the stomach from the swollen abdomen may lead to loss of appetite, and pressure on the lungs may lead to shortness of breath. When a doctor taps (percusses) the abdomen, the fluid makes a dull sound. When the abdominal cavity contains large amounts of fluid, the abdomen is taut, and the navel is flat or even pushed out. In some people with ascites, the ankles swell with excess fluid (edema). However, a doctor may not be able to detect ascitic fluid unless the volume is about a quart or more.
If the presence of ascites or its cause is not clear, the doctor may use ultrasonography. In addition, a small sample of ascitic fluid can be withdrawn by inserting a needle through the abdominal wall—a procedure called diagnostic paracentesis. Laboratory analysis of the fluid can help determine the cause.
The basic treatment for ascites is bed rest and a salt-restricted diet, usually combined with drugs called diuretics, which make the kidneys excrete more water into the urine. If ascites makes breathing or eating difficult, the fluid may be removed through a needle inserted into the abdomen—a procedure called therapeutic paracentesis. The fluid tends to reaccumulate unless the person also restricts salt consumption and takes a diuretic. Because a large amount of albumin (the major protein in plasma) is usually lost from the blood into the abdominal fluid, albumin may be administered intravenously.
An infection called spontaneous bacterial peritonitis occasionally develops in ascitic fluid for no apparent reason, especially in people with alcoholic cirrhosis. Untreated, this infection can be fatal. Survival depends on early vigorous treatment with antibiotics.
Adapted from: Merck & Co., Inc.