Flattened stools are considered to be caused by occupational lesions of the intestinal system, such as intestinal polyposis, rectal neurofibroma, and colorectal cell carcinoma. When fecal material passes through the lesioned tissue, the local obstruction of the passage can lead to changes in the shape of the stool. In addition, most patients with these diseases have complications such as lower abdominal pain, bleeding stools, and constipation. However, patients with diseases of the anal system, such as internal hemorrhoids, anal adenomas, and anal cancer, are also often associated with these adverse symptoms. In contrast to the former, the symptoms of these patients are anal pain, swelling, bleeding, etc. If there are any of these adverse symptoms, it is recommended to go to the hospital as soon as possible to receive further examination such as colonoscopy to confirm the specific cause of the disease.