There are three major causes of vague pain on the left side of women’s stomachs, as follows: 1. Gynecological diseases, adnexitis or chronic pelvic inflammatory disease, in addition to abdominal pain, there will be changes in leucorrhoea or changes in the nature of menstruation. In addition to abdominal pain, there will be changes in leucorrhea or changes in menstrual pattern. Dysmenorrhea is divided into primary dysmenorrhea and secondary dysmenorrhea, and nowadays secondary dysmenorrhea is more common in clinical practice, such as adenomyosis. In addition, gynecological malignant tumors, such as ovarian cancer, adnexal cancer or uterine cancer, should be excluded; 2. The left side of the abdomen is a transverse part of the rectum and sigmoid colon, so it is related to digestive system diseases. First of all, inflammation of the digestive system, such as colitis or ulcerative colitis, intestinal tumors, bacterial dysentery, etc. Any condition that can cause enteritis will cause abdominal pain; 3, urinary system diseases related, such as urinary stones, inflammation, tumors, etc. will cause abdominal pain on the left side.