Male patients with left-sided lower abdominal pain are seen for the following reasons: First, if the patient is middle-aged or elderly, it is not excluded that it is caused by intestinal tumors, mainly malignant tumors occurring in the descending colon, the patient will also have obvious changes in bowel habits, unformed stools, black stools or blood in the stool, there will also be obvious abdominal distension, after eating will induce the aggravation of symptoms, later there will also be a loss of appetite and weight loss, and anemia. The symptoms may be aggravated after eating, and later there may be loss of appetite and weight loss, and anemia. In severe cases, intestinal obstruction may also occur, which is considered to be related to ulcer malignancy or polyp carcinoma. Secondly, ulcerative colitis occurs more often in young patients, and there is also vague pain in the lower abdomen on the left side, which can be aggravated after eating irritating foods, and there are usually symptoms of repeated mucopurulent stools, which can be confirmed by colonoscopy.