Although medical errors such as amputating the wrong appendage(付属肢)or removing organs from the wrong patient are relatively rare, a new study finds that they occur more frequently than previously thought. Researchers determined that over a 6.5-year-period, Colorado doctors operated on the wrong patient at least 25 times and on the wrong body part a whopping(途方もなく)107 times. Despite these surprisingly high numbers, so-called wrong-patient and wrong-site procedures accounted for only about 0.5 percent of all medical mistakes analyzed in the study.