Difficult one, but Ethel is quite correct in her answer BUT
1) suppose there is no chaperonne available because of staff abscence or shortages...unusual perhaps.
2) If in a medical emergecy say, a GP went to the home and there was nobody to chaperonne e.g next door neighbour at work etc.
I feel in these circumstance providing that he had the permission of the patient and that he explained what he was doing, then an intimate examination could be performed without the prescence of a chaperonne.