Ascites Health Article

Description

Ascites is defined as an excessive amount of fluid built up within the peritoneal cavity. Both the abdominal organs and the abdomen itself are lined with membranes called the peritoneum. Between these two linings is a space referred to as the peritoneal cavity. In pathological conditions that result in edema, or excessive fluid accumulation in bodily tissues, fluid can build up in the peritoneal cavity.

Smaller abdominal fluid amounts usually do not produce symptoms. However, larger accumulations can cause:

• rapid weight gain
• abdominal discomfort and distention
• shortness of breath and actual dyspnea, or difficulty breathing
• swollen ankles

Severe cases of ascites can result in the retention of literally gallons (each gallon equals nearly four liters) of liquid in the peritoneal cavity. If fluid retention is sufficiently severe, the abdomen becomes swollen and even painful. Breathing can be affected as the fluid-filled peritoneal cavity presses upon the diaphragm, a very necessary component of respiration. The diaphragm is made up of a dome-shaped sheet of muscles that separates the thoracic, or chest, cavity from the abdomen. When the muscle fibers of the diaphragm contract, the space in the chest cavity is enlarged, and air enters the lungs to fill the enlarged space. When pressure on the diaphragm from fluid build-up occurs, it lessens the ability of these diaphragm muscular fibers to expand and contract, and results in impaired breathing.

Ascites, in itself, is not a disease, but rather a symptom of several other pathological conditions. These include:

• Cirrhosis of the liver, which is responsible for 80% of all instances of ascites in the United States.
• Pancreatic ascites develops when a cyst that has thick, fibrous walls (pseudocyst) bursts and permits pancreatic juices to enter the abdominal cavity.
• Chylous ascites, which has a milky appearance caused by lymph that has leaked into the abdominal cavity. Although chylous ascites is sometimes caused by trauma, abdominal surgery, tuberculosis, or another peritoneal infection, it is usually a symptom of lymphoma or some other cancer.
• Cancer causes 10% of all occurrences of ascites in the United States. It is most commonly a consequence of disease that originates in the peritoneum (peritoneal carcinomatosis) or of cancer that spreads (metastasizes) from another part of the body. Tumors especially prone to malignant ascites formation include ovarian cancer and metastatic gastrointestinal tumors.
• Endocrine and renal ascites are rare disorders. Endocrine ascites, sometimes a symptom of an endocrine system disorder, also affects women who are taking fertility drugs. Renal ascites develops when blood levels of albumin dip below normal. Albumin is the major protein in blood plasma. It functions to keep fluid inside the blood vessels.

Causes

The two most important factors in the production of ascites due to chronic liver disease are low levels of albumin in the blood and an increase in the pressure within the branches of the portal vein that run through liver (portal hypertension). Low levels of albumin in the blood cause a change in the pressure necessary to prevent fluid exchange (osmotic pressure). This change in pressure allows fluid to seep out of the blood vessels. The scarring that occurs in cirrhosis causes portal hypertension. Blood that cannot flow through the liver because of the increased pressure leaks into the abdomen and causes ascites.

Other conditions that contribute to ascites development include:

• hepatitis
• heart or kidney failure
• inflammation and fibrous hardening of the sac that contains the heart (constrictive pericarditis)

Persons who have systemic lupus erythematosus but do not have liver disease or portal hypertension occasionally develop ascites. Depressed thyroid activity sometimes causes pronounced ascites, but inflammation of the pancreas (pancreatitis) rarely causes significant accumulations of fluid.