Pain in the small abdomen before menstruation is common in clinical practice for the following reasons: first, chronic pelvic inflammatory disease, the pelvis is in a congested state before menstruation, causing congestion and edema in the original inflammatory tissue, so pain in the lower abdomen will occur. This pain often occurs after exertion in daily life or after sexual intercourse, but also pain, and will be manifested as more discharge, it is recommended to actively treat pelvic inflammatory disease. The second one, endometriosis, also presents with pain in the small abdomen before menstruation. It is recommended to do gynecological examination in both cases to find out whether there is pressure pain in the uterine adnexa, to find out whether there is a pelvic mass, and to do ultrasound examination to exclude the possibility of endometriosis.