There are many reasons for right abdominal pain, the most common reasons are the following: 1, may be caused by the right ovarian chocolate cysts, chocolate cysts are due to endometriosis, growth in the ovary inside the ectopic endometrium, ectopic endometriosis occurs in the menstrual period of shedding bleeding, bleeding accumulates in the ovary inside the flow does not come out, the formation of a similar chocolate-like cysts. Cysts form a mass compression, coupled with menstrual period pelvic cavity and annex uterus congestion, may cause lesion site pain. 2, may be ectopic pregnancy, ectopic pregnancy is the most common site is in the fallopian tube. The main symptom of early ectopic pregnancy is irregular vaginal bleeding, or accompanied by one side of the abdominal pain, in fact, is not a menstrual period.3, other causes, such as right adnexal space-occupying lesions, chronic adnexitis and other diseases, menstrual pelvic cavity and adnexal congestion, may also cause pain is more obvious. It is recommended to go to the gynecology department for ultrasound examination to see what the cause may be.