We’ve all heard stories of patients who experience unexpected or increasing pain after surgery, only to have their doctor later discover that a surgical instrument or sponge was left inside them. It may sound comical, but the reality is that surgical mistakes can be deadly, and a new study finds that they are actually more common than you’d think.

These surgical mistakes, called "never-events" (in that they should never happen), include leaving an instrument, sponge, or towel inside a patient; operating on the wrong site; performing the wrong procedure; or operating on the wrong person. A new study looked at records of the National Practitioner Data Bank (NPDB), which is a federal database of claims of medical malpractice, to determine just how often these events occur. Hospitals are required by law to report never-events to the NPDB. According to the data, about 80,000 of these never-events occurred between 1990 and 2010, which breaks down to over 4,000 per year. And, the authors say, this estimate is probably on the low side, since not all of the events are likely to be noticed, if the patient does not experience symptoms as a result.

Some of the methods hospitals use to reduce the instances of surgical mistakes include taking "timeouts" before the surgery to make sure that surgical plans and medical records correspond to the person on the operating table.

Of the events that occurred, 9,744 were paid malpractice judgments and cost roughly $1.3 billion. Looking at the outcomes for the people who had been victim to never-events, 6.6% of the patients died from the events; 32.9% of the people were permanently injured, and another 59.2% were temporarily injured. What’s especially disturbing, the authors stress, is that never-events are completely avoidable.

"There are mistakes in health care that are not preventable. Infection rates will likely never get down to zero even if everyone does everything right, for example," said study author Marty Makary in a news release. "But the events we've estimated are totally preventable. This study highlights that we are nowhere near where we should be and there's a lot of work to be done." Makary is the author of the book, Unaccountable: What Hospitals Won't Tell You and How Transparency Can Revolutionize Health Care, which we reviewed here.

Some of the methods hospitals use to reduce the instances of surgical mistakes include taking “timeouts” before the surgery to make sure that surgical plans and medical records correspond to the person on the operating table. Marking the surgical site on the patient with indelible ink is also used, as is a long-standing procedure of counting instruments and sponges before and after the surgery. Some facilities have also begun to use barcodes on surgical materials to reduce human error in the process.

But because the numbers are still so high, Makary supports making such mistakes a matter of public record, which would bring about a level of transparency that does not currently exist, and would allow patients more information when choosing a facility in which to have surgery. The study found that 12.4% of the surgeons studied were involved in more than one never-event, and 62% were involved in more than one malpractice report. Hospitals have to be pressured into making sure these events are reduced or eliminated, Makary believes. It is important to put “hospitals under the gun to make things safer.”

The study was carried out by a team at Johns Hopkins University School of Medicine, and published in the journal, Surgery.