The inability to pass half of the bowel movement may be caused by constipation, hemorrhoids, intestinal diseases and other reasons. 1. constipation: gastrointestinal peristalsis slows down, diet is too fine, drink less water, less exercise and other reasons may lead to the stool stays in the intestinal tract, the symptoms of defecation to half can not be discharged. 2. Hemorrhoids: Hemorrhoids are a symptom of congested and enlarged veins in the anal canal or lower rectum. It may cause obstruction of bowel movement, and the symptom of not being able to pass half of the bowel movement may occur. 3. Intestinal diseases: Intestinal diseases such as intestinal obstruction, intestinal polyps, intestinal tumors and so on, due to the narrowing or blockage of the passageway for the discharge of stools, the symptom of not being able to discharge half of the bowel movement may also occur. If you have the symptom of not being able to pass half of the bowel movement, you need to go to the hospital for further examination of colonoscopy, pathology biopsy and other programs to find out the cause.