Stool discharge in quadrilateral shape is related to gastrointestinal dysfunction, rectal-anal opening related lesions and other factors. 1. Gastrointestinal dysfunction: lack of dietary fiber-rich foods such as fresh vegetables and fruits in the daily diet, resulting in drier and harder stools, causing the bowel movements to be quadrangular. 2. Rectum, anal opening related lesions: intestinal inflammation, intestinal tumors, polyps and other occupational lesions, caused by organic lesions of the anus and intestines. Including anal hemorrhoids, polyps in the rectum, rectal cancer, etc., resulting in narrowing of the intestinal lumen, appearing quadrangular stool. It is recommended that the patient timely consultation, under the guidance of the doctor for fecal routine, anal fingerprinting, proctoscopy and other examinations, to clarify the cause of the disease, and follow the doctor’s instructions for targeted treatment.