What is the ruling on informing the doctor of the results if it becomes apparent that the bride is not a virgin, or on concealing this fact?

It is not permissible for a man to take his fiancée to a doctor to ascertain her virginity, because that is a form of ill-suspicion, prying into people's private matters, and exposing a severe awrah (intimate part) without necessity. Similarly, it is not permissible for a woman to go for an examination of her virginity and obtain a certificate to that effect, unless there is a need for it, such as an accusation or suspicion from which she wishes to be cleared. In such a case, she may be examined by a Muslim female doctor, or a non-Muslim female doctor, or a Muslim male doctor in the presence of a mahram (unmarriageable kin).