I don’t know much about yichud, I really need to look it up. But SaysMe, 1 on 1 with an oppisite gender is definetly yichud, there are itger types too, but 1 on 1 no doubt you need to keep a door open or have someone else there.
Wasnt there a story about a non-jewish dentist left with a jewish patient and during her treatment gave her a tranqulizer and…………ya, I bet you can guess what he did after.
In the end the found the dentist and got him arrested, but only after he had done this to a few patients.
Something could happen, what if she dosent tell you she’s leaving and your patient goes out cuz he forgot something and sees she’s gone????? You have to actually have someone there…..