What is the ruling of Islamic law regarding the defloration of a Muslim virgin due to chronic health conditions, where the doctor advises defloration because it prevents menstrual flow every month?

If defloration is the only way to cure a woman, and doctors have confirmed this, then there is no harm in performing a procedure to remove the hymen. This is based on the Almighty's saying: "And He has not placed upon you in religion any difficulty," and because Islamic jurisprudence is founded on the principle of alleviating harm.