A new study reports that each year in the United States doctors commit more than 4,000 “never events” -- the kind of medical mistake that should never happen. These errors include operating on the wrong part of the body or performing the wrong procedure or even performing surgery on the wrong patient altogether. Another common “never event” involves sewing up a patient after surgery and discovering – or worse, not discovering – that an instrument used in the operation was left inside the patient. These events occur, as The Wall Street Journal put it in reporting the study results, with “alarming frequency.” The study was led by Johns Hopkins University School of Medicine and was published in the journal Surgery. It used data in the National Practitioner Data Bank that includes information on medical malpractice judgments and settlements. The study identified 9,744 “never events” between 1990 and 2010, including 6 percent in which patients died and 33 percent in which they suffered permanent injury. Because the vast majority of cases never get reported and even fewer result in lawsuit verdicts or settlements, the study estimated the actual number of these egregious medical errors is 4,082 annually. Learn more about medical malpractice lawsuits.