The term for abnormal collection of fluid in the peritoneal cavity is:

Ascites. Ascites is the buildup of fluid usually serous fluid which is a pale yellow and clear fluid that accumulates in the abdominal (peritoneal) cavity. The most common cause of ascites is advanced cirrhosis of the liver, although other factors that may contribute to ascites are salt and water retention, include cancer, heart failure, tuberculosis, pancreatitis, and blockage of the hepatic vein. It usually has a number of symptoms which includes increased abdominal size, increased weight, abdominal discomfort, and shortness of breath.