The common causes of left-sided abdominal pain are as follows: 1, left-sided organ lesions: left-sided organ lesions, commonly found in the left half of the colon, upper rectum, rectal lesions, will cause left-sided abdominal pain. Inflammatory lesions, such as ulcerative colitis, will appear in the rectum and the mucous membrane of the left half of the colon erosion, ulceration, left lower abdominal pain. If neoplastic lesions occur in the left half of the colon, adenomas and cancers of the rectum and sigmoid colon, such as rectal and sigmoid colon cancer, pain in the left lower abdomen can also occur. In addition to colon diseases, some inflammatory diseases of the small intestine may also cause pain in the left lower abdomen, such as Crohn’s disease and intestinal tuberculosis. Through the digestive tract imaging or abdominal CT, usually can confirm the diagnosis, follow-up regular, standardized treatment; 2, plant nerve dysfunction: plant nerve dysfunction caused by intestinal dysfunction, can also cause left lower abdominal pain, manifested as intermittent pain, need to be given to correct the intestinal dysfunction of the drug and supplemental probiotic treatment; 3, the left side of the ureteral lesions: the left side of the ureteral lesions, such as ureteric Left ureteral lesions, such as ureteral stones, can cause pain in the left side of the abdomen; 4, female reproductive system lesions: female left ovary, fallopian tube inflammation, tumors, causing pain in the left lower abdomen, need to do ultrasound or pelvic magnetic resonance examination.