In France in the 60's, there was every year of school a mandatory school physical examination, it was not optional, you could not go to see a private doctor instead of reporting at the school physicals. If you were not available that day or were sick, the parents might inform the school authorities and you were summoned on an other day with another class of boys.
The school physical examinations took place generally on the second week of the year school after you have had at least one PE lesson and they lasted for two weeks .. in an only boys school.
Each year there was a letter sent to the parents a few days before but very short with the day and the hour of the exam, the name and gender of the doctor was not mentioned nor how thorough would be the exam.
It was just mentioned that it was mandatory and that each boy would be examined and that if the parents wanted that their son was exempted of sport or swimming they might give to him a medical exemption by a private doctor that he would show on his exam.
Nothing was said about exam of genitals and balls or about exam of anus area.. only the exam of the spine was generally mentioned because it was important to detect scoliosis or other issues.
What was always mentioned, even at high school, was that the parents might be sure that their sons were clean, so their sons might have taken a bath or washed on the morning of the exam day, and their sons might wear clean socks and clean underwear. Which meaned that we would have to undress at least until briefs. I must add that it was justified since we would have to wait with just a brief for at least one hour in group in the locker room under supervision of the PE teacher (no matter if we were naked after).
The day before a monitor came during a class to recall us that we had next day our physical examination and that we might take a bath or washed and have clean socks and underwear. It was embarrassing to be told by a monitor about the requirement to be clean in presence of a teacher.. but they did it each year of school, even at high school.
And the day of the exam, the Pe teacher asked to all the group who was instructed to undress all together in a waiting room if each boy had thought to change of socks and underwear.
What is funny was that the same requirement to be clean and to wear clean socks and underwear was mentioned also on the summon letter that our parents received before our report in front of the draft board commission. For a physical examination at 18 age for checking the fitness to military service and same for the summon to report at a military medical pre-induction center .
We were treated as if we were kids, always under authority and control of our parents which was legally true! Of course our mothers were careful about our socks and briefs on that day even if we knew and they knew that we will be examined stark naked, not wearing briefs!