Intestinal leakage is generally referred to as an intestinal fistula. The causes of intestinal fistula formation in adults are related to surgery, trauma, malignant tumors, radiation injury, chemotherapy, abdominal infections, and inflammatory diseases of the intestines. 1. Surgery: enterocutaneous fistula is a relatively common and serious complication after abdominal surgery. 2. Trauma: enterocutaneous fistula is formed due to perforation of the intestines as a result of severe trauma to the abdomen. 3. Malignant tumors: as tumor cells can cause invasion of the surrounding tissues and even lead to necrosis of the intestinal mucosa, the wound may form an intestinal fistula. 4. Radiotherapy and chemotherapy: the process of chemotherapy and chemotherapy may also cause intestinal fistula due to radiation as well as damage from chemotherapy drugs. 5. abdominal infection: abdominal infection or localized abscess after surgery may directly penetrate the intestinal wall and form intestinal fistula. 6. intestinal inflammation: inflammation of the small intestine, intestinal tuberculosis and other diseases, may also cause damage to the intestinal mucosa or even cause perforation, so it is also an important factor in the formation of intestinal fistula. Different causes of intestinal fistula, will be accompanied by other clinical manifestations, the specific circumstances need to meet with the doctor and analyze the patient’s condition.