So, turned to AskYahoo (nice service by the way) for an answer.
We've all heard the harried medical team on ER call for something "stat." From the context, we knew it meant "quickly," but had no idea what the normal definition of the term was. We turned to the Net to cure our ignorance.
After various searches on phrases like "stat terminology" and "stat meaning" failed to provide an answer, we sat down and rethought our strategy. Several of our searches had turned up acronyms for the term, and while they weren't what we were looking for, they did point us in a new direction.
Remembering a helpful site we'd used in the past, we pointed our browser to Acronym Finder, a web site devoted to decoding mysterious combinations of letters. Typing in "stat," we hit the "Find" button and awaited a diagnosis.
As it turns out "stat" stands for a number of things, ranging from the obvious (statistics) to the not so obvious (Society of Teachers of the Alexander Technique). However, the very first entry provided the answer to your question. "Stat" in medical parlance is actually not an acronym; it's short for statim, the Latin word for immediately.
That made sense, considering many medical terms have Latin origins. Next time we get a similar question, we'll know to head to our Latin dictionary. Stat.
Hope that helps eh? In the immortal words of Dr John Dorian.