What causes pain in the left lower abdomen?

Left lower abdominal pain may be caused by various factors, mainly including: 1. Gastrointestinal diseases: such as acute enteritis, ulcerative colitis, etc., which may be accompanied by symptoms like diarrhea or constipation; the pain is related to intestinal inflammation or functional disorders. 2. Urinary system diseases: such as ureteral stones; the pain may be accompanied by symptoms like urgency, frequency, or hematuria, and is related to stone irritation of the ureteral wall. 3. Gynecological diseases: such as inflammation or tumors of the left ovary or fallopian tube; the pain may be associated with menstruation, sexual activity, and other factors; diagnosis requires gynecological examination. 4. Other factors: such as autonomic nervous system dysfunction, acute inflammation of intra-abdominal organs, organ torsion, or rupture, which can also cause left lower abdominal pain.