There is a small amount of fluid in the abdominal cavity itself, but this fluid accumulation usually stays around 50ml. Therefore, it is recommended that patients must not worry too much if fluid is found in the abdominal cavity in the case of ultrasound examination of the abdomen, because as long as the amount of fluid does not exceed 50 ml, it means that it is a normal situation. It is recommended that the patient must combine clinical, as well as combined with the guidance of the physician to carry out the relevant treatment, to avoid excessive tension. Because the normal intra-abdominal fluid can play a protective role for the abdominal cavity, can cushion the external damage to the abdominal cavity, can effectively protect the organs in the abdominal cavity. If the amount of fluid in the abdominal cavity is greater than 50ml during ultrasound examination, it may be caused by disease, more commonly peritonitis, because peritonitis will form a large amount of exudate under the stimulation of inflammatory cells, which will cause an increase in the amount of solution in the abdominal cavity. It is recommended that the patient must promptly extract the peritoneal fluid for pathological testing, which can effectively clarify the diagnosis, and after the clear diagnosis must be actively treated symptomatically.