A woman who normally has normal menstrual cycles and normal menstrual flow suddenly experiences a decrease in menstrual flow, which may be caused by a woman’s emotional impact, or stress, or other reasons that affect the normal function of the gonadal axis, resulting in abnormal endometrial thickness. The most common cause is an increase in the thickness of the endometrium, which causes the endometrium to fail to peel off completely when menstruation occurs, resulting in a decrease in menstrual flow. In some cases, the endometrial lining is thin due to low estrogen levels in the body, resulting in a decrease in menstrual flow. In this case, an ultrasound examination can be done to find out the thickness of the endometrium. For women with an endometrial thickness of more than 15 mm, a diagnostic curettage can be done to rule out endometrial pathology. Some women also need to have a blood test for hormone 6 to understand the function of the ovaries.