under the knife

1. Undergoing surgery, as in He was awake the entire time he was under the knife. The phrase is often put as go under the knife meaning “be operated on,” as in When do you go under the knife? Knife standing for “surgery” was first recorded in 1880.

Example Sentences

Each time you go under the knife you are rolling the dice.

From BBC

She said the partnership with TikTok would help people "make safer and more informed choices before they go under the knife – wherever that may be."

From BBC

He was the first to go under the knife.

From Los Angeles Times

But as pitchers across baseball push for higher velocity, more hurlers are going under the knife — for a first time, a second time and in some instances, a third or fourth procedure.

From Los Angeles Times

As the ulnar collateral ligament epidemic has grown over the last decade — forcing players with elbow injuries under the knife for Tommy John surgery — and as openers and bullpen games have become more normalized in MLB, having the same five pitchers throw every fifth day has become a rarity.

From Los Angeles Times