Abdominal fluid is commonly caused by the following reasons, namely, inflammation of the abdominal cavity, abdominal tumors, liver disease, and hypoproteinemia, as follows: 1. If inflammation of the abdominal cavity occurs, such as acute appendicitis, the inflammation will lead to leakage of fluid from the abdominal cavity, thus leading to abdominal fluid. 2. If tumors occur in the abdominal cavity, such as gastric cancer and colon cancer, they will lead to leakage of fluid from the blood vessels into the abdominal cavity, thus causing abdominal fluid. 3, If liver disease occurs, such as cirrhosis, it can lead to portal hypertension and hypoproteinemia, which can lead to peritoneal effusion. 4. If hypoproteinemia occurs, the water in the blood vessels can seep into the abdominal cavity, which can also lead to peritoneal effusion. After the occurrence of peritoneal effusion, patients need to go to the hospital in a timely manner and need to improve relevant examinations, such as blood routine, ultrasound, CT, liver function, etc., to be able to clarify the cause, and then can be treated for the cause.