Does a clinical medical examination involving the insertion of medical instruments or fingers into a fasting patient's body cavity or a fasting woman's private parts invalidate the fast?

Introducing a medical endoscope or a female doctor's hand into a woman's vagina does not affect her fasting, according to the sound (correct) opinion. However, if medical instruments are introduced into a patient's body through the mouth and are accompanied by liquids, this breaks the fast. If they are not accompanied by any liquids, the fast is not broken. Merely inserting fingers into the mouth does not invalidate the fast, unless one intentionally vomits.