There is usually no liquid in the abdomen, but small amounts called peritoneal fluid are occasionally present to help organs within the abdominal cavity move smoothly, according to eMedicineHealth. Ascites is the term for an abnormal accumulation of fluid in the abdomen.
The peritoneum is a tissue that covers both the abdominal wall and the abdominal organs, such as the stomach, intestines and liver. Certain disorders may cause the peritoneum to produce excess amounts of fluid, which build up in the abdominal cavity. One of the most common causes of ascites is liver disease. This causes the liver's protein production to decrease, which leads to water leaking out of the bloodstream and into tissues, according to eMedicineHealth. Other causes include cancer, heart failure, or blockage of the lymph nodes.
Symptoms of ascites include bloating, abdominal pain, loss of appetite, frequent urination and fatigue. Ascites due to cancer tends to cause pain, whereas ascites due to liver disease does not. To test for peritoneal fluid buildup, doctors may perform imaging tests such as an ultrasound scan or CT scan, according to Cancer Research UK. Additionally, they may order blood tests to check liver and kidney function or take a sample of fluid to look for cancer cells or infectious agents such as bacteria or viruses.