"Abbreviations in letters"

Received a letter advising me of an appointment at Stirling Community Hospital with the abbreviation BAU used. Why do they need to attempt to hide information by using abbreviations. So according to a google search BAU could mean business as usual or was associated with Basal cell carcinoma removal, which sounds a bit more worrying. Fortunately the letter does say dermatology which helps but I am a below knee amputee with a prosthetic and had queried some strange skin behaviour and scarring on the residual limb of my amputated limb at the prosthetic clinic and think that this is what the appointment is about. However I had best check, which probably means spending an hour on the phone tracking someone down who actually knows about the letter and also what the appointment is in connection with.