I had such an exam. I was 16 years old.
One of my classmates punched me on the face and then forced me to lower my briefs, without going further, even though he had also lowered his own and had an erection. I did not mention the sexual aspect to my parents.
My father was a mailman and knew police officers well. They advised us to show the injury at a clinic. I went there with my mother. I was injured only around one eye, but the doctor asked me to undress in the presence of my mother, I could keep my briefs. I considered this as a second aggression. The doctor made remarks about my scoliosis and asked questions that had nothing to do with the assault.