Traumatic as hell to read and think about. It is a hell of a situation to be in from any angle, especially as it comes to defying the "wisdom" of transphobic medical professionals.
[Edit 2010/01/18: The destination post has since been locked, so I'm opening comments. One thing that transgendered and other non-gender-binary people have to think about that the rest of us have the privilege of not considering: if I am lying in the hospital unable to make my wishes known, will they address me by the correct name and gender? Even if the people closest to me know my correct name and gender and address me by it, will they be overruled by transphobic medical staff? Link included hellishly traumatic story with real names redacted. Include this in your in-case-the-worst-should-happen documentation and legal papers.]