Stomach pain before bowel movement may be caused by dry stool, irritable bowel syndrome, intestinal tumors and other factors. 1. Dry stool: before defecation, feces need to enter the sigmoid colon and rectum, if the stool is dry, it may cause mechanical stimulation to the intestinal wall, so that the nerve of the intestinal wall is compressed, which will lead to the symptom of stomach pain before defecation. 2. Irritable Bowel Syndrome: Visceral sensitivity may increase in irritable bowel, which is overly responsive to intestinal contents and the dynamics of intestinal lumen dilation. Before bowel movement, intestinal peristalsis increases, and stomach pain before bowel movement may also occur. 3. Intestinal tumor: When there is a tumor growing in the intestines, narrowing of the intestinal lumen may occur. Before defecation, feces need to be pushed downward through the narrowed area, which may cause irritation to the narrowed area, thus leading to stomach pain before bowel movement. There are many other causes of stomach pain before bowel movement. When stomach pain before bowel movement occurs, you should consult a doctor in time, and improve the fecal routine, colonoscopy, CT and other tests under the guidance of the doctor, to clarify the cause of the disease, and actively treat it.