Stool with pus on the left side of the lower abdomen pain, consider may suffer from bacillary dysentery, colitis, acute gastroenteritis and other diseases. 1. Bacterial dysentery: Bacterial dysentery is an infectious disease of the intestinal tract caused by infection with fats and bacilli. This pathogenic microorganism may invade the intestinal mucosa, resulting in clinical symptoms such as mucopurulent blood stool, urgency, abdominal pain and diarrhea. 2. Colitis: Suffering from left-sided colitis, such as ulcerative colitis and treatment-related enteritis, can lead to a state of congestion and edema of the intestinal mucosa, which may also cause lower abdominal pain on the left side of the stool with pus. The occurrence of this disease may be considered to be related to autoimmune function abnormalities, drug stimulation, radiotherapy side effects and other factors. 3. Acute gastroenteritis: Eating food contaminated by bacteria and other pathogenic microorganisms can induce an inflammatory reaction in the gastrointestinal tract, which will secrete pus and may cause pain in the lower abdomen on the left side of the stool with pus. Stool with pus left lower abdominal pain, there may also be related to other causes. It is recommended to go to the hospital as soon as possible, and cooperate with the doctor to complete the routine stool, colonoscopy and other related examinations, has a clear cause, so as not to delay the condition.