Suddenly a few days stool quadrangular, the possible causes are hemorrhoids, intestinal polyps, intestinal tumors and so on. 1. Hemorrhoids: part of the population frequent sedentary, long standing or unhealthy diet, etc., may cause internal hemorrhoids, the condition of more serious cases is likely to form a blockage or narrowing of the rectum, so that the people suffering from this disease in the defecation of the stool shape changes or defecation difficult situation. 2. Intestinal polyps: This is a condition that runs in families, followed by bad habits. People suffering from the disease often have no obvious symptoms in the early stage, with the gradual increase in the size of the polyp, it may cause extrusion of the stool in the rectum and make it change its shape, and in serious cases, blood in the stool may also occur. 3. Intestinal tumor: clinically, this kind of disease is mostly seen in colon cancer and rectal cancer, which is related to individual diet, inflammation stimulation, hereditary polyps, etc. The increase of tumor volume will affect the shape of stool and make it appear quadrangular or angular, and part of the population will also be accompanied by symptoms such as urgency and heaviness, and frequent bowel movements, etc. If the stool is quadrangular for a long time, the tumor may cause the stool to change its shape, and in serious cases, blood in stool may also occur. If the four-pronged shape of the stool persists for a long time, it is recommended to go to the gastroenterology department of the hospital for consultation and targeted treatment.