Merck Manual

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Danielle Tholey

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Jan 2023

Ascites is the accumulation of protein-containing (ascitic) fluid within the abdomen.

Causes of Ascites

The most common cause of ascites is

  • Liver disease

Ascites tends to occur in long-standing (chronic) rather than in short-lived (acute) liver disorders. It most commonly results from

Ascites may occur in other liver disorders, such as severe alcoholic hepatitis without cirrhosis, other kinds of chronic hepatitis, and obstruction of the hepatic vein (Budd-Chiari syndrome Budd-Chiari Syndrome Budd-Chiari syndrome is caused by blood clots that completely or partially block blood flow from the liver. The blockage may occur anywhere from the small and large veins that carry blood from... read more ).

In people with a liver disorder, ascitic fluid leaks from the surface of the liver and intestine and accumulates within the abdomen. A combination of factors is responsible. They include the following:

Also, albumin usually leaks from blood vessels into the abdomen. Normally, albumin, the main protein in blood, helps keep fluid from leaking out of blood vessels. When albumin leaks out of blood vessels, fluid also leaks out.

Symptoms of Ascites

Small amounts of fluid within the abdomen usually cause no symptoms. Moderate amounts may increase the person's waist size and cause weight gain. Massive amounts may cause abdominal swelling (distention) and discomfort. The abdomen feels taut, and the navel is flat or even pushed out.

The swollen abdomen puts pressure on the stomach, sometimes leading to loss of appetite, and pressure on the lungs, sometimes leading to shortness of breath.

Complications of ascites

Spontaneous bacterial peritonitis (infection of the ascitic fluid that develops for no apparent reason) sometimes occurs. This infection is common among people with ascites and cirrhosis Cirrhosis of the Liver Cirrhosis is the widespread distortion of the liver's internal structure that occurs when a large amount of normal liver tissue is permanently replaced with nonfunctioning scar tissue. The scar... read more Cirrhosis of the Liver , especially people who drink large amounts of alcohol.

If spontaneous bacterial peritonitis develops, people usually have abdominal discomfort, and the abdomen may feel tender. People may have a fever and feel generally unwell. They may become confused, disoriented, and drowsy. Untreated, this infection can be fatal. Survival depends on early treatment with appropriate antibiotics.

Diagnosis of Ascites

  • A doctor's evaluation

  • Sometimes an imaging test such as ultrasonography

  • Sometimes analysis of ascitic fluid

When a doctor taps (percusses) the abdomen, the fluid makes a dull sound. If the person's abdomen is swollen because the intestines are distended with gas, the tapping makes a hollow sound. However, a doctor may not be able to detect ascitic fluid unless the volume is about a quart or more.

If doctors are uncertain whether ascites is present or what is causing it, they may do ultrasonography or computed tomography (CT; see Imaging Tests of the Liver and Gallbladder Imaging Tests of the Liver and Gallbladder Imaging tests of the liver, gallbladder, and biliary tract include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), endoscopic retrograde cholangiopancreatography... read more ). In addition, a small sample of ascitic fluid can be withdrawn by inserting a needle through the wall of the abdomen—a procedure called diagnostic paracentesis Paracentesis Paracentesis is the insertion of a needle into the abdominal cavity for the removal of fluid. Normally, the abdominal cavity contains only a small amount of fluid. However, fluid can accumulate... read more Paracentesis . Laboratory analysis of the fluid can help determine the cause.

Treatment of Ascites

  • A low-sodium diet

  • Diuretics

  • Removal of ascitic fluid (therapeutic paracentesis)

  • Sometimes surgery to reroute blood flow (portosystemic shunting) or liver transplantation

  • For spontaneous bacterial peritonitis, antibiotics

The basic treatment for ascites is a low-sodium diet with a goal of 2,000 mg or less of sodium per day.

If diet is ineffective, people are usually also given drugs called diuretics (such as spironolactone or furosemide). Diuretics make the kidneys excrete more sodium and water into the urine so people urinate more.

If ascites becomes uncomfortable or 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 people also follow a low-sodium diet and take a diuretic. Because a large amount of albumin is usually lost from the blood into the abdominal fluid, albumin may be given intravenously.

If spontaneous bacterial peritonitis is diagnosed, people are given antibiotics such as cefotaxime. Because this infection often recurs within a year, a different antibiotic (such as norfloxacin) is given after the initial infection resolves to prevent the infection from recurring.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Aldactone, CAROSPIR
Delone , FUROSCIX, Lasix
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