go under the knife
slang To undergo surgery. My dad is going under the knife on Thursday to try and clear the blockage in his heart.
go under the knife
Fig. to submit to surgery; to have surgery done on oneself. She goes under the knife tomorrow for her gallbladder. Frank lives in constant fear of having to go under the knife.
go (or be) under the knife
have surgery. informalgo under the ˈknife
(informal) have a medical operation: Peter hates his nose so much that he’s seriously considering going under the knife to have it made smaller.