Sigmoid polyp surgery three months after the left lower abdominal pain accompanied by the stool is not shaped, may be due to intestinal function is not restored, acute enteritis, tumors and other diseases. 1. The intestinal function is not recovered: after the operation of sigmoid polyp, it will cause stimulation to the gastrointestinal tract, resulting in the dysfunction of gastrointestinal system, which will cause the patient’s left lower abdominal pain and the symptom that the stool is not shaped. 2. Acute enteritis: patients consume unclean or too much spicy, raw and cold food, which will lead to the emergence of acute enteritis. After the emergence of acute enteritis, patients will have symptoms such as unshaped stool and pain in the left lower abdomen. 3. Tumor: rectal cancer and colon cancer will press the gastrointestinal tract with the increase of tumor, which will lead to severe pain in the left lower abdomen, blood in stool, unshaped stool and other symptoms. Three months after the operation of sigmoid polyp, the patient should consult the doctor in time for examination and treatment in order to avoid delaying the condition.