Gas in the stomach is caused by intestinal obstruction, intestinal paralysis, intestinal tumors and other diseases. Under normal circumstances, the intestinal cavity is open, but when the intestinal mucosa is severely inflamed or stacked, the intestinal tract becomes blocked, so the contents of the intestine cannot be excreted normally. In case of complete intestinal obstruction, not only the food residues in the intestine cannot be eliminated, but also the gas in the intestine cannot be excreted, and the abdominal distension and pain may occur. In some people, after intestinal surgery, the blood supply to the intestine is impaired, so the balance of the nervous system in the intestine is impaired, the intestine cannot expand, and the peristalsis of the intestine disappears, which then induces an attack of intestinal paralysis. An attack of intestinal paralysis is caused by the inability of the contents to push forward, so gas and defecation will stop. Intestinal tumor is a malignant disease that can seriously affect the bowel function. Many patients will have a change in bowel habit after the disease. In severe cases, there will also be gas and defecation because of the slow peristaltic process of the intestine.