Menstrual odor is mostly caused by gynecological inflammation, mostly seen in gynecological vaginitis or endometritis, as follows: 1. Vaginitis: there are three most common types of vaginitis in women, including mycosis vaginalis, trichomonas vaginalis and bacterial vaginosis, which can cause abnormal odor of leukorrhea or menstruation. Bacterial vaginitis causes the most obvious odor, bacterial vaginitis is a kind of gynecological inflammation caused by anaerobic bacteria multiply in the vagina, dysfunction of the flora, it will lead to vaginal secretions or menstrual blood is fishy or ammonia odor. 2, endometritis: women with endometrial inflammation, the endometrial lining of the menstrual period when the lining shedding, it may also cause the menstrual blood has a bad smell. If a woman’s menstruation has a foul odor, mostly represents a gynecological inflammation, the patient must go to the hospital to do the appropriate examination, clear which kind of inflammation, and then targeted treatment.