"In which medical context do we say doctors have “assigned” something that they have checked and noted?"
Well I think the point is that it is slightly more complicated than A+ or AB- or whatever.
As I understand it the current 'assigned' trend actually dates from the 50s. A doctor declared that gender was socialized and used as an example the case of en.wikipedia.org/wiki/David_Reimer where after a botched medically indicated (but unnecessary) circumcision led the boy to be experimented on by Dr. John Money, who performed a sex change on the boy, which, naturally, the doctor declared to be a wonderful success.
"Reimer said that Money forced the twins to rehearse sexual acts involving "thrusting movements", with David playing the bottom role. Reimer said that, as a child, he had to get "down on all fours" with his brother, Brian Reimer, "up behind his butt" with "his crotch against" his "buttocks". Reimer said that Money forced David, in another sexual position, to have his "legs spread" with Brian on top. Reimer said that Money also forced the children to take their "clothes off" and engage in "genital inspections". On at "least one occasion", Reimer said that Money took a photograph of the two children doing these activities. Money's rationale for these various treatments was his belief that "childhood 'sexual rehearsal play'" was important for a "healthy adult gender identity"."
Money was for all appearances a paedophile, even being interviewed in Paidika, the scientific journal 'by paedophiles for paedophiles', saying a mutual sexual relationship between a boy of '10 or 11' and a man in his 20s or 30s is 'not pathological', and apparently appeared in almost every issue of said journal.
Anyway, Money's point, which was then accepted, was that you could simply socialise children as girls or boys and so the best thing was to operate on them as soon as possible.
So broadly speaking you had for :
- from an antiquity an examination of genitals to determine the true sex - where genitals were ambiguous, further examination would determine the 'true sex'
- from the 1950s a 'optimal gender' policy whereby a child would be operated on to obtain 'correct' genitals which they would be socialised according to. This model reflects the following beliefs:
(a) that gender is a preference, and essentially an expression of arbitrary societal explanations, and therefore should be socialised according to the appearance of the subject.
(b) that the gender assigned in infancy determines the likely adult gender, not biological markers.
- subsequent to this time there is now a fuller understanding of the role of hormones at different stages in development and what we have now is an 'optimal gender' policy that reflects specific conditions. For example an XY individual with complete androgen insensitivity (due to a mutated gene) will grow up female, because the male hormones - from prior to birth - have had no influence on the body or brain of the subject.
OTOH, an XY cloacal exstrophy, where a child is born potentially with no penis at all - and who according to Dr. Money should have a vagina carved out of him, because that is the 'optimal gender' for someone with no penis - will grow up male. The condition is merely a genital abnormality and male testes should not be removed, because the newborn baby is ALREADY male, the process of masculinization having occurred in utero from a few weeks gestation as a result of their male sex hormones. www.isna.org/node/564
So now intersex people are 'assigned' a gender according to the known outcomes for their (sometimes very rare) conditions. This assignment is no longer accompanied with gender reassignment operations, as it is better for the adult intersex person to make a determination for themselves. What it is a statement that person A's condition means they will grow up female or male as the case might be.
I think the interesting issue is that whereas we went from in antiquity saying 'you are female' or 'you are male', to quacks in the 50s saying it was a matter of socialisation and totally arbitrary, and while that appears discredited along with its quacks, people want to continue with that and say 'my gender is whatever I say it is', even though there is no evidence for that, even though we have more evidence now for assignment.