Irregular stool shape may be caused by intestinal dysfunction, chronic enteritis, colon tumor and other reasons. 1. Intestinal dysfunction: usually stools are formed in the sigmoid colon, if the intestinal absorption of water is relatively reduced, the stools will become loose, and the patient may have paste-like stools and mucus-like stools. 2. Chronic enteritis: irregular stool shape may also be caused by chronic enteritis, chronic enteritis mainly refers to the chronic inflammatory disease in the intestinal tract, which is easy to recur and lasts for a long time. Chronic enteritis is mainly caused by a variety of microbial infections such as bacterial, fungal or viral infections or immune factors, and the main symptoms include nausea, diarrhea, abdominal pain and so on. 3. Colon tumor: colon tumor is a kind of common malignant tumor, which mainly manifests as change of bowel habit and character, abdominal pain, abdominal distension, abdominal mass, anemia, low fever and other symptoms, and it can also cause irregular shape of stool. There are many reasons for irregular stool shape, and patients are advised to actively seek medical advice and regular treatment under the guidance of doctors.