Hymen generally refers to the vaginal flap, just broken on menstruation is usually the vaginal flap rupture of the normal bleeding, or the time of sex just before the onset of menstruation, there will also be just broken vaginal flap on menstruation, are normal phenomena. However, it may also be related to other factors, such as taking certain medications, polyps, tumors or blood disorders. 1. Normal bleeding from a ruptured vaginal flap: The hymen, often referred to as the hymen in clinical practice, is a thin membrane that covers the area around the vaginal opening of a woman’s vagina and is often ruptured when a woman has sex for the first time, frequently engages in activities such as riding a bicycle, or frequently cleanses the vulva. The rupture of the vaginal flap usually leads to a small amount of vaginal bleeding, pain in the vaginal opening, etc. Generally, the above symptoms will gradually improve after 2-3 days, and menstruation just after the rupture of the vaginal flap is usually normal bleeding from the rupture of the vaginal flap, which is normal and no need to worry about it too much. 2. The onset of menstruation: If the time of the above mentioned sexual behaviors happens just before the onset of menstruation, the situation of menstruation just after the vaginal flap has been broken will also occur, which is also a normal phenomenon. 3. Other factors: irregular vaginal bleeding may also occur in cases such as polyps, tumors, blood diseases or taking certain medications. Therefore, if this situation occurs, it is recommended to go to the hospital in time for examination, to clarify the cause of the disease, and then follow the doctor’s instructions to deal with the treatment.