The main reasons for abdominal pain and chest distension, but no menstrual flow include the following: 1. Early pregnancy reaction: If the usual menstrual cycle is normal and regular, and in the reproductive age, while having sex and no contraception, it may be pregnancy, at which time an early pregnancy test of urine can be performed. Because the reaction of early pregnancy can lead to abdominal pain, chest distension, loss of appetite, while there is no menstrual flow; 2. Gynecological diseases: If the patient excludes the possibility of pregnancy, it is necessary to check whether there are gynecological diseases, for example, due to the intake of more cold food, cold, can cause obstruction of menstrual excretion, thus triggering the symptoms of abdominal pain and chest distension.