When doctors sewing up a patient after an operation inadvertently leave surgical equipment like sponges inside the body, the result can harm or even kill the patient. Such mistakes also cost hundreds of thousands of dollars in further treatment and legal costs. Along with taking out the wrong kidney or operating on the wrong person, leaving a sponge in a patient is the kind of avoidable medical nightmare that health-care quality experts consider a never event—that is, it should never happen.

It’s hard to know precisely how often it does. A review at the Mayo Clinic in Rochester, Minn., from 2003 to 2006 found a rate of about one “retained foreign object” case for every 5,500 surgeries. Another analysis of 20 years of malpractice settlements found that such incidents were the most common “never events,” with an estimated 2,024 claims per year, or a rate of more than five each day. The U.S. has no comprehensive system for measuring how often doctors mistakenly leave items in patients’ bodies. The lack of data itself is revealing, when you consider, for example, how scrupulously aviation accidents are tracked.

The most common approach for making sure all sponges come out of patients is to count them as they go in. But the current counting methods “are prone to human error,” according to an October report (PDF) by the Joint Commission, a nonprofit that certifies health-care providers on quality standards. Counts are wrong about 10 percent to 15 percent of the time, and most cases where sponges are left in the patient “occur with what staff believe is a correct count,” according to the report.

Stryker, the $9 billion-revenue medical-device maker, is betting on technology that will help improve those counts. On Monday it acquired a small company called Patient Safety Technologies, which makes a system of bar-coded sponges and electronic counters that will read the codes even on a sponge soaked in blood. The transaction was valued at $85 million, according to data compiled by Bloomberg.

Executives from Stryker and Patient Safety Technologies were not available for an interview on Tuesday. Patient Safety Technologies had revenue of about $20 million in the 12 months through September 2013. A list of roughly three dozen clients on its website includes the Mayo Clinic, the Cleveland Clinic, Brigham and Women’s Hospital, and the U.S. Department of Veterans Affairs.

A few other companies make high-tech sponges intended to reduce the risk that absent-minded doctors will leave one behind, including RF Surgical Systems and ClearCount. Stryker’s acquisition puts a global sales force behind the technology.

Better sponges may help, but eliminating serious medical errors requires a cultural shift inside operating rooms and hospital executive suites. The Joint Commission report draws the parallel to air travel: “High reliability science studies organizations such as those in the commercial aviation industry, which manage great hazard extremely well, and in which the goal is zero harm,” the document says. “In order to achieve high reliability, leadership must commit to this goal, the culture must support workers who identify and report unsafe conditions,” and organizations need to measure the problem by, for example, tracking the number of days since a foreign object has been left inside a patient. Bar codes on the sponges are only a start.

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