The Food and Drug Administration has acknowledged that more than 56,000 never-before-disclosed surgical stapler malfunctions were quietly reported to the agency from 2011 through 2018.

The newly acknowledged reports were detailed in an executive summary for FDA advisers. The agency convened a meeting of experts this week to help it determine whether surgical staplers should be moved out of its lowest-risk category — reserved for simple devices like tongue depressors and bandages — to a higher grade that may require testing and additional oversight. Surgical staplers are used to cut and seal vessels and tissues inside the body.

When the FDA initially announced the meeting in March, it acknowledged in a letter to doctors that "many more device malfunction reports" were reported to the agency than it had publicly disclosed. The FDA executive summary published this week shows that the total reports more than doubled when the agency took nonpublic reports into account, totaling nearly 110,000 malfunctions or injuries from 2011 through 2018.

"It shocks the conscience," said Chad Tuschman, a lawyer representing Mark Levering, 62, of Toledo, Ohio, who suffered a serious brain injury after a stapler malfunction caused massive bleeding in 2018. The surgeon, hospital and device maker Covidien, a division of Medtronic, have all denied allegations of wrongdoing in an ongoing legal case.

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Surgical staplers have a unique ability to harm patients if they malfunction. Often used in minimally invasive surgeries, they are meant to both cut tissue and vessels and then quickly seal them. Patients have been gravely harmed when staplers have failed to fire or seal tissue, suffering from massive bleeding or infections if stomachs or intestines aren't sealed properly.

The nonpublic reports were sent to the FDA as "alternative summary" reports, the topic of a recent Kaiser Health News investigation that focused on the agency accepting millions of hidden reports related to medical devices — including for surgical staplers.

The agency had previously acknowledged that in 2016, even as it posted fewer than 100 stapler-related injuries in a public database called MAUDE, it accepted nearly 10,000 reports into its little-known internal alternative summary reporting database. (The data in the FDA's executive summary contains reports for staplers and staples, which experts have said were just different names for the same problem.)

Tuschman said he was stunned that there were more hidden reports than public ones in the executive summary. "The first question should be 'Why?' Why would they have the right to submit to a hidden database?"

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Leading surgical stapler makers include divisions of Medtronic and Johnson & Johnson. Medtronic has said the FDA granted it exemptions for stapler-related malfunctions; Johnson & Johnson said it has not. (Ethicon is the name of its subsidiary medical devices company.)

On Thursday, the advisory panel recommended switching surgical staplers to a higher-risk classification with additional safety requirements, according to meeting attendee Jack Mitchell, director of health policy for the nonprofit National Center for Health Research. FDA spokeswoman Stephanie Caccomo declined to confirm this, citing a media office policy against telling reporters what happens at advisory committee meetings, which are open to the public.

"Every surgeon that I have ever worked with has had stapler failures," said Dr. Doug Kwazneski, a Michigan surgeon who authored a survey in 2013 about "unacknowledged" stapler problems after searching the FDA's public database of device incidents and coming up empty-handed.

"Going into something without data is dangerous," Kwazneski said. "If the information exists, we should have access to it."

More than 400 deaths have been reported since 2011 in the FDA's public MAUDE database; fatalities can't be reported to the alternative summary reporting database. Deaths were associated with Ethicon and Covidien products.

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In recent communications about stapler safety to doctors, the FDA has advised against using the staplers on large blood vessels.

Kwazneski said surgical staplers are a time-saving tool, which lessens the risk of anesthesia complications during surgery, for example. But it's important for physicians to remember they can fail.

Diana Zuckerman, president of the National Center for Health Research, said that alternative summary reports are "a well-kept secret" and that any reports related to their existence were "done in a way that was not understood as a repository for hundreds of thousands of serious adverse event reports."

Mitchell said he was surprised the FDA didn't reclassify surgical staplers "a long time ago," considering the agency had the additional 56,000 alternative summary reports all along. "They were the only ones who had this information, and it was nonpublic."

Kwazneski suspected that there were a high number of hidden reports for stapler malfunctions, but he said the numbers revealed in the FDA's executive summary still came as a shock.

"The sheer magnitude of seeing it all at once kind of blew my mind," he said.

Staplers lost their eligibility to report malfunctions through the hidden system in February 2019, and the FDA announced it would end the alternative summary reporting program earlier this month. It has promised to make that data public in the "coming weeks."