Ascites is the medical term for the abnormal and pathological accumulation of fluid in the peritoneal cavity. The peritoneal cavity is the space within the abdomen that is enclosed by a thin membrane called the peritoneum, which covers the abdominal walls and most of the organs. In a healthy person, this space contains only a very small amount of lubricating fluid. In ascites, liters of fluid can accumulate, causing significant abdominal swelling and discomfort.

To understand why this happens, it is essential to understand the primary mechanism that causes it: portal hypertension.

• The portal vein is a major blood vessel that acts like a highway, collecting all the nutrient-rich blood from the spleen and digestive system and carrying it to the liver to be filtered and processed.
• In a person with severe liver scarring, or cirrhosis, the hardened liver tissue resists blood flow.
• A helpful analogy is to think of the liver as a large, complex filter. In cirrhosis, this filter has become clogged and hardened. This makes it very difficult for blood to pass through, causing a massive traffic jam and a buildup of pressure in the portal vein highway. This condition is called portal hypertension.
• This intense pressure forces clear, watery fluid to “weep” or leak out from the surface of the liver and intestines. This fluid collects in the path of least resistance, the empty space of the peritoneal cavity leading to the accumulation of ascites.

Another major contributing factor is a low level of a protein called albumin. A healthy liver produces large amounts of albumin, which acts like a sponge in the bloodstream to hold fluid inside the blood vessels. In advanced liver disease, the failing liver cannot produce enough albumin. This combination of high pressure pushing fluid out (portal hypertension) and low protein failing to hold fluid in (hypoalbuminemia) is the perfect storm for the development of severe ascites.

In my experience, patients usually describe ascites as a “sudden belly heaviness” that makes it hard to bend or breathe, especially when the fluid buildup becomes significant.

The development of ascites is always a sign of an underlying disease process that has disrupted the body’s normal mechanisms for regulating fluid.

Cirrhosis of the Liver

This is the single most common cause, accounting for approximately 80% of all cases of ascites. Cirrhosis is the end-stage scarring of the liver from many different types of chronic liver disease. The most common causes of cirrhosis worldwide include:

• Chronic Alcohol Abuse: Long-term, excessive alcohol consumption is a leading cause of liver damage.
• Chronic Viral Hepatitis: Persistent infection with Hepatitis C or Hepatitis B can lead to cirrhosis over many years.
• Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Formerly known as nonalcoholic fatty liver disease (NAFLD), this is a condition linked to obesity, type 2 diabetes, and high cholesterol, where fat accumulation leads to liver inflammation and scarring.
• Autoimmune Hepatitis and Primary Biliary Cholangitis (PBC): Autoimmune conditions where the body’s immune system attacks its own liver cells or bile ducts.

Non-Liver Causes

While less common, other conditions can also cause ascites.

• Cancer: Cancers that have spread to the lining of the abdomen (peritoneal carcinomatosis) are a common non-liver cause. This is frequently seen with ovarian, uterine, pancreatic, and colon cancers. Lymphoma can also cause ascites.
• Heart Failure: Severe, congestive heart failure, particularly on the right side of the heart, can cause fluid to back up throughout the body’s venous system, leading to both ascites and swelling in the legs.
• Kidney Disease: A condition called nephrotic syndrome, where the kidneys leak massive amounts of protein (including albumin) into the urine, can lead to low protein levels in the blood and cause severe, generalized swelling and ascites.
• Pancreatitis: Severe inflammation of the pancreas can sometimes lead to the leakage of pancreatic fluid into the abdomen.
• Tuberculosis: In some regions, tuberculous peritonitis can cause inflammatory ascites.

Clinically, I’ve often seen cirrhosis as the leading cause, but I also remind patients that heart failure, cancer, and kidney problems can lead to fluid accumulation in the abdomen.

A person develops ascites as a consequence of having an underlying disease that progresses to an advanced stage. Therefore, the risk factors for developing ascites are the risk factors for these root conditions, particularly chronic liver disease.

You are at a higher risk of developing ascites if you:

• Have a history of long-term, heavy alcohol use.
• Have chronic Hepatitis B or C.
• Are obese and have type 2 diabetes or metabolic syndrome.
• Have a diagnosed autoimmune liver disease.
• Have certain types of cancer that can spread to the abdomen.
• Have congestive heart failure or advanced kidney disease.

In my experience, people living with untreated hepatitis or chronic alcohol use often develop ascites gradually, as their liver loses the ability to manage fluid balance.

The symptoms of ascites are primarily caused by the physical pressure and weight of the accumulated fluid in the abdomen.

The hallmark signs that point to the development of ascites are:

• Progressive increase in abdominal size and girth.
• Rapid, unexplained weight gain.

As more fluid accumulates, other symptoms will develop. These include:

• A feeling of bloating, pressure, and abdominal tightness or discomfort.
• Shortness of breath (dyspnea). This is a very common symptom and occurs because the large volume of fluid pushes up on the diaphragm, restricting the ability of the lungs to fully expand.
• Loss of appetite and a feeling of getting full very quickly (early satiety), as the fluid presses on the stomach.
• Swelling in the ankles and legs (peripheral edema).
• The development of a new umbilical or inguinal hernia, caused by the high pressure inside the abdomen pushing a piece of tissue through a weak spot in the abdominal wall.
• Indigestion or heartburn.
• Lower back pain.

Patients often describe a sense of tightness or fullness in the abdomen, and many feel breathless even after small meals especially when the fluid becomes excessive.

A doctor often suspects ascites based on a patient’s medical history and a physical examination showing a distended abdomen. The diagnosis is then confirmed with imaging, and a crucial procedure is performed to analyze the fluid and determine the cause.

• Physical Examination: A doctor can perform specific maneuvers, such as percussing the abdomen (tapping it) to listen for the sound of fluid (“shifting dullness”) or trying to elicit a “fluid wave.”
• Imaging:
  • Abdominal Ultrasound: This is the most common and easiest way to confirm the presence of ascites. It is a non-invasive test that can detect even small amounts of fluid. It can also provide valuable images of the liver, showing signs of cirrhosis.
  • CT Scan or MRI: These tests can also confirm the presence of fluid and provide more detailed images of the abdominal organs, which can be helpful for identifying a potential cause like a tumor.
• Diagnostic Paracentesis (Abdominal Tap): This is the most important diagnostic test once ascites is confirmed. It is a procedure where a doctor uses a thin, sterile needle to withdraw a small sample of the ascitic fluid directly from the abdomen. This fluid is then sent to a laboratory for analysis.
  • Cell Count and Differential: This measures the number of white blood cells in the fluid. A high number of a specific type of white blood cell (neutrophils) is the key to diagnosing a serious infection called Spontaneous Bacterial Peritonitis (SBP).
  • SAAG (Serum-Ascites Albumin Gradient): By comparing the level of albumin protein in the ascitic fluid to the level in the blood, doctors can determine the cause of the ascites..
  • Culture: The fluid is placed in culture bottles to see if any bacteria will grow, which also indicates an infection.
  • Cytology: The fluid is examined under a microscope to look for any malignant cancer cells.

Clinically, I usually confirm ascites through a physical exam and an ultrasound, it’s quick, noninvasive, and helps assess both fluid amount and underlying causes.

The treatment of ascites is focused on managing the fluid buildup to relieve symptoms and prevent complications. The ultimate goal is to treat the underlying disease that is causing the ascites.

1. Sodium and Water Restriction (The Foundation)

The cornerstone of managing ascites from liver disease is a strict low-sodium diet. Sodium causes the body to retain fluid. Patients are typically advised to restrict their sodium intake to less than 2,000 mg per day. This involves avoiding processed foods, canned goods, and adding no salt to food during cooking or at the table. Fluid restriction may also be recommended in some cases.

2. Diuretics (“Water Pills”)

These medications are used along with a low-sodium diet. They work by helping the kidneys excrete excess sodium and water from the body into the urine. The standard combination of diuretics used for cirrhotic ascites is spironolactone and furosemide.

3. Large-Volume Paracentesis (LVP)

For patients with tense, uncomfortable ascites or those who do not respond well to diuretics, LVP is a therapeutic procedure to provide immediate relief.

• In this procedure, a doctor drains a large volume of fluid, often 4 to 5 liters or more, from the abdomen using a catheter.
• This provides rapid relief from shortness of breath and abdominal pressure.
• During an LVP, patients are often given an intravenous infusion of albumin to help maintain their blood pressure and circulatory function.

4. Management of Complications Spontaneous Bacterial Peritonitis (SBP)

It is a life-threatening infection of the ascitic fluid. Any patient with ascites who develops a fever, abdominal pain, or confusion must seek immediate emergency medical care. SBP requires hospitalization and treatment with powerful intravenous antibiotics.

5. Advanced Procedures

For patients with refractory ascites that is difficult to control with diet and diuretics, more advanced procedures may be considered.

• TIPS (Transjugular Intrahepatic Portosystemic Shunt): This reduces portal hypertension and can be very effective at controlling ascites.
• Liver Transplantation: For patients with end-stage liver disease, a liver transplant is the only definitive cure for both the underlying cirrhosis and the ascites.

Clinically, I’ve seen the best outcomes when we combine sodium restriction, diuretics, and close monitoring patients often feel better within days of reducing fluid overload.

Ascites is not a disease, but a serious and visible sign of an advanced underlying medical condition, most commonly chronic liver disease and cirrhosis. The development of a swollen abdomen from fluid buildup marks a critical point in a person’s illness and demands a thorough medical investigation to determine the cause. While the appearance of ascites is a serious sign, it can be managed. Through a dedicated partnership with a liver specialist (hepatologist), a strict adherence to a low-sodium diet, and the use of diuretic medications, the fluid can be controlled. This proactive management is key to improving comfort and quality of life, and serves as a vital bridge to treating the root cause of the problem or, in advanced cases, to a life-saving liver transplant.

American Liver Foundation. (n.d.). Ascites. Retrieved from https://liverfoundation.org/liver-diseases/complications-of-liver-disease/ascites/

American College of Gastroenterology (ACG). (2021). Ascites. Retrieved from https://gi.org/topics/ascites/ The Merck Manual Professional Version. (2023). Ascites. Retrieved from https://www.merckmanuals.com/professional/hepatic-and-biliary-disorders/ascites/ascites