I've had more painful and seen more incompetence on the medical professionals' side, but my methacholine challenge as part of asthma diagnosis always stands out for the blatant malpractice.

I was a kid, probably range of 9-12 years old. They exposed me to something that eventually triggers an asthma reaction in anyone, just a matter of how much it takes to be considered "asthmatic". Then they left me in the room alone while the test ran. I posted about it once as a sanity check. It's a legitimate test, from what I've been able to find, just not the part when they leave an underage patient unattended to deal with the inevitable asthma attack alone.

https://reddthat.com/post/48901213