Menstruation with a small amount of blood clots mostly belong to normal physiological phenomena, normal menstrual blood for the non-clotting venous blood, but due to physiological factors affecting the discharge of menstrual blood, in the uterine cavity stays too long, may lead to a small amount of blood clots formed. There are mainly the following reasons: First, long time inactivity, if during the menstrual period, long time sitting on the chair inactivity or in the case of resting at night, the menstrual blood in the uterine cavity can not be discharged out of the vagina in a timely manner, in the uterine cavity for a long time to stay in the uterine cavity may form a clot in the process of standing up or getting out of bed and then discharged. Second, cold stimulation, some women like to eat cold food, or used to use cold water to wash their face, feet, in the menstrual period if the slightest cold stimulation, may lead to menstrual blood clots. Third, menstrual blood, menstrual blood is relatively more women, a short period of time if there is more endometrial stripping caused by bleeding, but also prone to blood clotting performance.