Does the expression "to go under the knife" carry a negative connotation?
Is there a difference in connotation between these two phrases?
I asked my student whether her mother was scheduled to GO UNDER THE KNIFE this morning.
I asked my student whether her mother was scheduled to UNDERGO SURGERY this morning.
In other words, would it be polite to ask somebody the question "When's she going under the knife?" in the informal register? Or would it sound too brutal or insensitive? (The "knife" part makes me think of a butcher, to be honest.)
It has the negative connotation that one is about to undergo surgery!
Since no surgery is completely without risk, and most is followed by a period of pain or discomfort, any expression describing it inherently contains a negative.
For that reason, we might euphemistically talk of "going into theatre"; a form of synecdoche, where the act of going into the place where surgery is performed stands for the whole process of going in there and having surgery performed. (We also use the same euphemism of the surgeons, theatre nurses, anesthesiologist, etc. who perform the surgery).
"Go under the knife" is a mild dysphemism, that doesn't add a negative connotation so much as focus on that which is already there.
This sort of bluntness can have a sort of euphemistic effect though, in a manner not unakin to gallows humour. Some people find it more comfortable to address the negative than to talk around it.
This sort of bluntness would require a degree of familiarity to be appropriate, and from that the ability to judge whether the person hearing it would indeed be the sort to prefer it.
It's also favoured as a dysphemism in more impersonal, informal writing. In journalism we'll find it used more of elective procedures, than for emergency or clearly required procedures, because "chose to go under the knife" both efficiently covers that a risk, and often a subsequent period of pain and discomfort, was entailed in that choice, as well as being a more vivid expression than the alternatives.
'Under the knife' is very casual. You would not want to say it to a student or a friend preparing for surgery as it sounds harsh, even scary. 'Preparing for surgery' or 'preparing for an operation' is the polite and tactful (that is to say, more comfortable, less alarming) way of saying it.