The main symptom of sigmoid bleeding is blood in the stool, which is a disease of the lower gastrointestinal colon. The colon is divided into four segments: ascending colon, transverse colon, descending colon and sigmoid colon, when the sigmoid colon has inflammation, tumors, polyps, etc. can cause blood in the stool. Depending on the amount of bleeding, blood in the stool can be acute haemorrhage, chronic small amount of bleeding or intermittent bleeding. If the bleeding is heavy and rapid, it appears bright red. If the bleeding is low and slow, it appears dark red. The stool can be seen to have whole blood or blood mixed with stool, or it can be attached to the surface of the stool or drip blood from the anus after defecation. In addition to blood in the stool, abdominal pain can also be present, for example, in ulcerative colitis abdominal pain can occur in the form of bloody or purulent stools, and the abdominal pain can be relieved after the stool, accompanied by a feeling of urgency or anal swelling, as well as fever, general bleeding tendency, abdominal masses, etc.