What Is Ascites?

By jolene

Reviewed: Dr. Gromatzky

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The term “ascites” is of Greek origin and can be translated to mean “sac” or “bag.” This term is used to describe an abnormal collection of fluid in the abdominal cavity. Normally, men have little to no fluid in their peritoneal cavity while women can have as much as 20 ml depending on their menstrual cycle.

Some experts define ascites as having more than 25 ml of fluid in the peritoneal cavity. In developed countries, the most common cause of ascites is due to liver cirrhosis. However, ascites can also occur due to tuberculosis, cancer, pancreatitis, heart failure, blockage of the hepatic vein, and more. This article will focus on ascites associated with cirrhosis.

1. Mechanism

The fluid accumulates due to excess sodium and water in the body. However, the cause of this imbalance is unclear. It is postulated that it may be due to portal hypertension (75% of cases), and inflammatory, infiltrative, and infective conditions. Three theories have been suggested: overflow, underfilling, and peripheral arterial vasodilation. In the overflow theory, the kidneys are thought to retain abnormal amounts of water and sodium. In the underfilling theory, it is suggested that fluid sequestration lowers the blood volume. This then results in water and sodium retention. In the peripheral arterial vasodilation theory, it is suggested that portal hypertension causes dilation of the blood vessels, which causes the blood pressure to drop. The body compensates by retaining more sodium and water, which causes fluid overflow into the peritoneal cavity.