A new study of medical errors presents a frightening hypothesis: its authors say it is basically a coin flip whether or not you will be the victim of a mistake when you go into surgery.

The study, based on observations of more than 275 operations at Massachusetts General Hospital, concluded that an error was made in half of all procedures. Many of these errors put the patient’s health and life at risk.

The study focused on anesthesia teams during the perioperative period, which refers to immediately before, during and after an operation. Researchers found that medical mistakes were highly common during that time. The most common errors involved medication errors such as administering improper doses and mislabeling a drug. Another common type of mistake observed by the researchers was failure to notice troubling changes in the patient’s vital signs.

Patients survived the vast majority of these mistakes, with fewer than two percent of the errors deemed life-threatening by the MGH study. However, the study described 69 percent of the errors as “serious” and another 30 percent as “significant,” so MGH patients were frequently put at serious risk by negligent medical staff.

In a masterpiece of understatement, the lead author of a study that found medical errors in half of the operations at the hospital it examined said there is “room for improvement in preventing perioperative medication errors.”

Indeed, the odds of being exposed to medical malpractice should be much lower than 50/50. Whether this rate is unique to MGH is not clear from an article on the subject by The Daily Beast.