The high volume of menstrual blood is often clinically caused by: 1. abnormal clotting time and thrombocytopenia, which can cause increased menstrual flow. 2. submucosal fibroids growing into the uterine cavity, which affects the contraction of the uterus. This can lead to an increase in menstrual flow and a larger clot in the menstrual blood, which is clinically recommended to be treated surgically. 3. Excessive hyperplasia of the endometrium caused by endocrine disorders, so there is a thickening of the endometrium, which clinically leads to an increase in menstrual flow. 4. Long-term use of certain drugs, such as taking a large amount of progesterone, causes the endometrium to thicken. This usually leads to vaginal bleeding after stopping the medication and can cause an increase in menstrual flow.