Normally, menstrual blood does not have clots, because menstrual blood is non-clotting. If there are very small clots during menstruation, it is clinically normal. If there is a large blood clot, it is often due to the following reasons: First, the most common reason is the presence of submucosal fibroids, or the presence of larger fibroids between the muscle walls, which increases the relative size of the endometrial area and also affects the contraction of the uterus, so that clinically there is a large blood clot during the menstrual period. Secondly, because of the clinical inflammation of the endometrium or the presence of polyps in the endometrium, the phenomenon of blood clots in menstrual blood can occur and is often accompanied by the possibility of dysmenorrhea. Therefore, once you find a large blood clot in your menstrual blood, it is recommended to go to the hospital in time to do the corresponding examination to exclude the possibility of organic lesions, according to the results of clinical intervention for this situation, if there are fibroids, if necessary, surgery should be given for treatment.