It's often not very useful for healthcare professionals to know your agab. In many cases it's used to discriminate against us and misdiagnose us (if you've heard the term "trans broken arm syndrome" then you know what I mean) If I need a prostate exam, the doc can know I'm a woman who has a prostate. But there's no need to use an inaccurate and bigoted term like "biological male".

I was assigned a sex at birth, not born with one. Based on genital appearance alone at birth it would be prudent to assume my chromosomal sex and endocrinological sex might be classified as male as well by a medical provider. However that might not be the case at all. What is sex though really?

That's a version of sex from Bean's Velocci's The history of sex research: Is “sex” a useful category?

It's a dangerously harmful term in medical settings. It's far more likely to lead to incorrect treatment than correct treatment.

Treating trans women as biologically male in medical settings can get us killed. That's how you end up prescribing a trans woman a male-typical dose for a medication, when in fact her body will respond to metabolize the medication along the female model. Calling trans women biological men is how you end up with trans women dying of breast cancer, because the insurance company decided that "biological males" don't qualify for regular mammograms.

I've experienced this myself. Usually I avoid outing myself as trans to doctors whenever possible. I keep it need-to-know. Because even well-meaning doctors can often be extremely ignorant, making assumptions based on "biological sex." For example, at a university I attended, I used the student health clinic for my healthcare. The clinic was extremely pro-trans. They asked people's pronouns and respected them. But they also ask your assigned sex at birth, and that's where things went off the rails. They viewed transness as an "identity," rather than something that meaningfully alters your biological sex.

The one case that sticks out is when I had them order some blood work. And, because some dingbat figured I was "biologically male," they ordered the bloodwork with the male reference ranges. And of course the bloodwork came back with several markers flagged as outside the normal range. Some medical dumbass decided I was biologically male, so therefore my blood should look like a man's. Oh, and I also then have to worry about problems of getting insurance to cover treatment, as this introduces a mismatch between the gender marker on my ID and the lab order.

Thankfully I caught their error, and we were able to correct it. And thankfully it wasn't something that would have affected anything even if they used the male reference ranges. But in another setting? If I was say, unconscious in a hospital? This could really hurt me. This could kill me in the wrong setting. I have an estrogen-dominated endocrine system; my body does not metabolize medications like a man's. If there is some medication where giving a woman a male-typical dose would kill them, giving me that dose would kill me.