Unfortunately they have to act as if
everyone is given the culture we live within...
I have knowlege of several teen virgins asked to submit to a pregnancy test-
bad idea, good medicine, (does not pass the sniff test)
whatever the culture we live in, such a step is, sadly, absolutely necessary. having to do that is bad, but we should never take it personally - even when it's our own daughter.
it's not that the doctor thinks poorly of the person being examined but absolutely needs confirmation of the person's status as a matter of professional duty. it's an essential part of the standard of care and medical protocol. as laymen (i.e. not doctors), we think of such an action as a moral judgment on a person; but a medical professional sees it as a crucial fork in the road for prescribing what sort of medical care is in order.
physicians are used to being lied to. many a self-proclaimed "virgin" or "chaste woman" has turned out to be lying to the doctor for whatever reason(s). (same with the self-proclaimed "chaste men" for that matter.) the doctor must know if a patient is pregnant before prescribing certain medications or ordering certain tests such as an xray. to do otherwise could kill/injure that patient or her unborn child. hence the precaution of ordering such a test.