Hidden pain in the left lower abdomen but normal stool may be caused by trauma, colon spasm, sigmoiditis and other reasons. 1. trauma: it is due to the damage caused by external force, accidentally knocked into the left lower abdomen, resulting in minor damage to the internal organs, the symptoms of hidden pain will occur, but the general function of the intestinal tract has not been significantly affected, so the stool can be in normal. 2. Colonic spasm: Colonic spasm is caused by intestinal motility, secretion dysfunction, and the gas in the intestine will also lead to intestinal spasm, so it will cause intestinal pain. 3. Sigmoiditis: It is a kind of inflammatory bowel disease confined to the sigmoid colon, and pain will occur under the stimulation of inflammation, usually occurring in the lower abdomen, and it will not affect the change of bowel movement when the condition is mild. It is recommended to go to the hospital for examination, the doctor will be based on clinical symptoms to give the appropriate judgment, clear cause of the disease and timely symptomatic treatment.