When menstruation causes stomach pain, it is often caused by the following reasons: First, because of its sensitivity to prostaglandins, the uterus will contract during menstruation, resulting in the feeling of stomach pain, this condition is clinically known as primary dysmenorrhea. Second, menstrual stomach pain caused by certain diseases, such as endometriosis, inflammation of the uterus and pelvis can cause pain in the lower abdomen when menstruation. In this case, we should actively treat the original disease, for example, if there is pelvic inflammatory disease, we should actively reduce inflammation, and if there is endometriosis, we should give active treatment. Thirdly, for menstrual pain caused by malformation of the uterus, ultrasound examination is recommended.