The causes of stomach pain during menstruation and particularly low menstrual flow are often clinically due to the following reasons: first, first of all, the possibility of pregnancy should be ruled out. Some women have a history of menopause just after pregnancy, such as vaginal bleeding on the 31st or 32nd day of menopause, and accompanied by pain in the lower abdomen. To exclude the possibility of preeclampsia and ectopic pregnancy. Secondly, clinically, we should exclude the possibility of pelvic inflammatory disease, if there is pelvic inflammatory disease to menstruation will appear stomach pain, and clinically due to pelvic inflammation will lead to the destruction of the cells of the ovarian tissue, so it will make the amount of menstruation change. Thirdly, clinically, the possibility of endometriosis should be excluded. If this situation occurs, it is recommended to do blood HCG test, gynecological examination, and clinical ultrasound examination.