When some British doctors are speaking informally with each other about waking up a patient, they may use a dated phrase to describe what they’re doing: “knock up.” A golden oldie, this phrase seems to have evolved from the days when doctors paid house calls, which involved knocking on the front door and occasionally waking up patients in the process.
In the U.S., the expression “knock up” is amusing because it means to impregnate someone. Many Britons have adopted this American use for the term, which may explain why in the UK, the older (and more innocent) meaning for the phrase is being, um, put to bed. After all, if a doctor knocks up a patient in the wrong way, he or she would be prosecuted.
As an aside, the term “knock up” has an alternate meaning in Britain. If you’ve ever watched a tennis match during the Championships of Wimbledon, you may have heard the expression “knock up.” It refers to practice play before the game or warming up by knocking the ball around.