urgent/emergent operation

I don't know if the use of emergent meaning "having the nature of an emergency" (as opposed to "just beginning to emerge or appear") is new or not, but I was totally unaware of it until a few years ago when I heard it from a doctor.  I believe that to a doctor, "emergent" is more serious than "urgent."  An urgent problem can be treated tomorrow, but an emergent situation needs to be treated immediately.  (I'm obviously not a doctor, so this might not be corrrect, but this is my understanding.)  I would add that not everyone outside the medical field is familiar with this usage of "emergent"; most people would just say "an emergency operation."  In fact, I'm not sure if "emergent" can be applied to the operation at all -- I know a problem can be described as "emergent," but I'm not sure if the treatment would also be described that way. 

Boy, I was sure a lot of help, wasn't I??

Is there anyone in the medical field who can clarify this?

No, (unfortunately, in my opinion,) the medical community actually uses "emergent" as a synonym, or near-synonym, for "urgent."  In fact, in my dictionary I see that "urgent" is given as the fifth definition of "emergent."  Apparently my idea that "emergent" was more of an emergency than "urgent" is not necessarily true -- google "urgent/emergent" and you will see that lots of medical-related documents use the combination "urgent/emergent" as the alternative to "non-urgent."

Ugh.  What was wrong with "emergency" used as an adjective?  To  me, "emergent" suggests something that is just beginning, rather than something that has already reached crisis level.