The pain in the right lower abdomen when menstruation occurs is often clinically caused by the following reasons: 1, because of endometriosis lesions in the right ovary, such as ovarian chocolate cysts in clinical practice, in this case, when menstruation occurs, the endometrium is shed and bleeding occurs, then the ectopic lesions will also appear bleeding phenomenon, so it will manifest as pain in the right lower abdomen. 2. Because of inflammatory changes in the right adnexal area, such as inflammation of the fallopian tubes, ovaries, or uterine ligaments, when menstruation occurs, the inflammation will be aggravated by congestion and edema, so that pain in the right lower abdomen will occur during menstruation, and a gynecological examination after menstruation can make a preliminary diagnosis. It is recommended to actively give anti-inflammatory treatment.