The most common causes of pain in the left abdomen are as follows: a. Spleen diseases, such as spleen tumor, spleen abscess, etc. will cause obvious pain in the left upper abdomen, and patients are suggested to improve CT examination of the spleen. Colorectal tumors, including colon and rectal cancers, manifest as hidden pain in the left abdomen, blood in the stool, diarrhea, urgency and heaviness, etc. Patients are recommended to improve tumor marker examination, colonoscopy and other examinations. Urinary system stones, mainly left ureteral stones, often cause left lower abdominal cramps, and the pain often spreads to the perineum, and some patients may have left lumbar pain. Fourth, if a female patient has left abdominal pain, it may be an adnexal disease, such as adnexitis, adnexal tumor, etc. It is recommended to improve ultrasound examination in gynecology department.