Normally, menstrual blood is dark red and is non-clotting and clot-free. If the menstrual blood is bright red, it is often related to the following factors: 1. Submucosal fibroids in the uterus. As submucosal fibroids grow into the uterine cavity, the endometrial area is relatively larger, which also affects the contraction of the uterus, causing an increase in menstrual flow and turning the blood bright red. 2. Due to polyps in the endometrium. Polyp in the endometrium is equivalent to a foreign body in the uterine cavity, which also affects the contraction of the uterus and makes the menstrual blood turn bright red. 3. In addition, if the menstrual blood is bright red and the volume is relatively high, endometrial lesions, such as excessive endometrial complex hyperplasia or endometrial cancer, should be considered. It is recommended to have an ultrasound examination after the menstruation is clean, mainly to understand the condition of the endometrium, and whether there is myoma growth in the uterus itself It is recommended to have an ultrasound examination after menstruation to find out the endometrial condition, whether there is any fibroid growth in the uterus, and whether there is any abnormality in the pelvis. Based on the results, the next step of treatment will be done, and if necessary, diagnostic scraping will be done.