There are many reasons for heavy menstrual flow with blood clots: 1. If a woman of childbearing age has a history of sexual intercourse and does not use contraception, the possibility of pregnancy should be ruled out if she has heavy menstrual flow with blood clots. Some incomplete or complete miscarriages may also result in heavy vaginal bleeding with blood clots. 2. Some organic lesions of the uterus, such as endometrial polyps, submucosal fibroids or intermucosal fibroids protruding into the uterine cavity, or adenomyosis, may cause heavy menstrual flow with blood clots. 3. 4. In adolescent or menopausal women, anovulatory menstrual bleeding may lead to excessive menstruation. 5. Oral contraceptives may cause menstrual disorders and excessive menstruation. If there is excessive menstruation with blood clots, it is recommended to promptly consult a regular hospital to identify the cause for targeted treatment.