Only one I heard of was during high school during the physicals. Where i'm from we used to have the occasional physical during the years in high school and almost always one before leaving high school, probably mostly for screening purposes.
This one time after physicals, the girls told us (yes my med fetish was strengthened by this!) that during the end of that check-up, the doctor pulled down the panties on some of them so that the unfortunate girl stood with the panties at her knees in front of a male doctor and the school nurse. The doc didnt do anything other than look and then they were allowed to pull their panties up and get dressed. This must have been quite a shock for the girls it happened to, as they werw all 16-17 years old at the time. I remember they were mad and embarrassed about it but we didnt know at the time why it happened.
We, or I, realised that the doc pulled the panties down on the girls with smallish breasts. Now I know that the most likely reason for that is to check tanner stage. I cant remember that the girls said the doc offered any explanations at the time though.