Well, this makes us never want to go under the knife for any reason whatsoever. Surgeon and author Marty Makary revealed in the Wall Street Journal that "U.S. surgeons operate on the wrong body part as often as 40 times a week." Though the horrifying stat can yield nervous jokes about awaking to find a leg instead of an arm missing, Makary uses it to prove his point that there is an culture of error among doctors. "As doctors, we swear to do no harm," he writes. "But on the job we soon absorb another unspoken rule: to overlook the mistakes of our colleagues." He even admits to having almost operated incorrectly himself:

Imagine that a surgeon is about to make an incision to remove fluid from a patient's right lung. Suddenly, a nurse breaks the silence. "Wait. Are we doing the right or the left chest? Because it says here left, but that looks like the right side." The surgery was, indeed, supposed to be on the left lung, but an intern had prepped the wrong side. I was that doctor, and that nurse saved us all from making a terrible error.

But surgery is just one example of how much can go wrong: about a quarter of all people hospitalized will be further harmed by a medical error.

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