Ascites

Ascites is the abnormal accumulation of fluid in the peritoneal cavity, which is the space between the lining of the inside of the abdomen (peritoneum) and the abdominal organs. Healthy individuals have a small amount of peritoneal fluid to prevent friction when the viscera move naturally, but if the volume increases, it causes discomfort and may affect vital functions.

The causes of ascites, which is a symptom of an underlying disease rather than a disease itself, are varied. Therefore, identifying the underlying cause as early as possible is essential in order to apply the most appropriate treatment in each case.

Ascites is classified into four types depending on the characteristics of the accumulated fluid:

• Chylous ascites: chyle accumulates, which is a milky-appearing lymphatic fluid, as a consequence of rupture or obstruction of the lymphatic vessels.
• Exudative ascites: the fluid, which appears cloudy, has a high content of proteins and inflammatory cells. It is usually caused by an infection or the formation of a cancerous tumor.
• Hemorrhagic ascites: red blood cells are present in the accumulated fluid, indicating internal bleeding. It is associated with neoplasms, trauma, cirrhosis, or vascular rupture.
• Transudative ascites: the fluid contains few proteins, ruling out an infectious or inflammatory origin. It is common in cases of cirrhosis or heart failure.

The presence of fluid in the abdomen, although uncomfortable, does not in itself pose a life-threatening risk to the patient. Therefore, the prognosis of ascites depends on the severity of the underlying disease and any comorbidities the patient may have.

Symptoms

The main symptoms of ascites, which may appear gradually or suddenly, are:

• Abdominal pain.
• Abdominal distension: visible enlargement of the abdomen, sensation of fullness, and pressure.
• Weight gain without an apparent cause.
• Loss of appetite.
• Edema (fluid accumulation) in the legs.
• When a large amount of fluid accumulates, shortness of breath due to elevation of the diaphragm and compression of part of the lungs.

When the amount of fluid accumulated in the abdomen is small, the condition is usually asymptomatic.

Causes

Ascites occurs when the body's physiological systems stop functioning properly or fail to work in a coordinated manner, which is essential to maintain the internal balance required for normal body function. The main contributing factors are:

• Portal hypertension: increased pressure in the portal veins that carry blood to the liver, thereby impairing venous return.
• Renal retention: the kidneys retain water and sodium as a consequence of dysfunction in neurohormonal mechanisms.
• Increased permeability of venous capillaries.
• Low blood albumin levels: this protein exerts the osmotic pressure necessary for water to remain inside the blood vessels. When albumin is deficient, fluid filtration into the abdominal cavity is promoted.

The diseases capable of causing these physiological alterations include:

• Benign ascites: caused by non-oncological diseases.
  • Liver cirrhosis: this is the most common cause of ascites. Scar tissue forms in the liver as a consequence of excessive alcohol consumption or diseases such as hepatitis (viral infection causing liver inflammation) or non-alcoholic steatohepatitis (fat accumulation and inflammation of the liver).
  • Congestive heart failure: chronic disease in which the heart does not pump blood properly, increasing venous pressure and promoting fluid accumulation in the abdomen, lungs, or legs.
  • Infections: some of the most common are peritoneal tuberculosis (bacterial infection caused by Koch’s bacillus) or brucellosis (infectious disease caused by Gram-negative bacteria).
  • Nephrotic syndrome: kidney disorder causing excessive protein loss through the urine, leading to decreased blood albumin levels.
  • Pancreatitis: due to rupture or leakage of the pancreatic duct.
• Malignant ascites: associated with cancer-related diseases.
  • Peritoneal cancer: a rare type of tumor that develops in the peritoneal membrane.
  • Peritoneal carcinomatosis: metastasis from cancers originating in other organs (usually the ovaries, colon, pancreas, or stomach), spreading cancer cells to the peritoneum.

Risk factors

Factors that increase the risk of ascites include:

• Excessive alcohol consumption.
• High-sodium diet.
• Hypoalbuminemia: low blood albumin levels.
• Portal hypertension.
• Liver diseases.
• Kidney diseases.
• Heart diseases.
• Ovarian, pancreatic, liver, or colon cancer.

Complications

Ascites may lead to the following complications:

• Spontaneous bacterial peritonitis: infection of the ascitic fluid accumulated in the abdomen, usually caused by E. coli or Klebsiella, leading to fever, abdominal pain, and impaired kidney function. It is common in patients with cirrhosis.
• Hepatorenal syndrome: kidney failure without structural kidney damage, making it reversible. It results from insufficient blood supply due to constriction of the blood vessels.
• Abdominal hernias: increased internal pressure may cause abdominal contents to protrude outward. Inguinal and umbilical hernias are the most common.
• Refractory ascites: accumulation of abdominal fluid that does not respond to treatment with diuretics and salt restriction or that rapidly recurs after paracentesis (medical procedure used to remove fluid).

What specialist treats ascites?

Ascites is diagnosed and treated within the specialty of Gastroenterology. General surgeons or Internal medicine physicians may also be involved.