[Sarai]

I think you might be surprised.
Villages here in Alaska with the same population as McMurdo have labs that are sometimes actually bigger than the one I work at in a larger city, because of the isolation. Obviously, by screening everyone beforehand you avoid the need to do a lot of testing, but wherever people get injured they'll need blood transfusions, and there's never a med tech far behind. Whether it's a traditional rotating stock blood bank or McMurdo's "walking" blood bank, there's still got to be someone to crossmatch the blood and I'd be very surprised if doctor's knew how to do that.
I can't even find which company (beyond the Australian Arctic Division, which doesn't list positions at McMurdo) is hiring for that doctor. So obviously I'm missing something.