A total of 12 patients may have died since 2016 due to complications from weight-loss balloon surgery, the Food and Drug Administration reported Monday.

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The surgery is used to treat obesity with liquid-filled intragastric balloon systems in conjunction with diet and exercise. The balloons function by taking up space in a patient’s stomach through the mouth and then filling with saline solution, according to the FDA.

While the deaths haven’t been definitively blamed on the devices, several incidents reported happened one to three days following the procedure. Many deaths involved tears in the esophagus or stomach that appeared after the balloon or balloons were inserted.

The FDA is monitoring two specific systems after five patient deaths were reported last year.

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Officials are keeping an eye on the Orbera Intragastric Balloon System from Austin, Texas-based Apollo Endosurgery and San Clemente, California-based ReShape Lifesciences' ReShape Integrated Dual Balloon System, according to Monday's news release.

Four of the five new cases are associated with the Orbera system and one is related to the ReShape system.

"We have been working with the companies that manufacture these liquid-filled intragastric balloons to better understand the complications associated with these devices." FDA spokeswoman Deborah Kotz told CNN.

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This isn’t the first time the agency has issued alerts about the devices, Kotz said. In February and August 2017, the FDA warned health care providers of adverse events and deaths associated with the balloon systems.

New labeling for the devices have also been approved to include more information about possible death risk, according to the FDA.

"While these reports are alarming, they have to be kept in proportion with the total number of balloons placed," New York obesity surgeon Dr. Mitchell Roslin told CNN. "As with any foreign body placed in the [gastrointestinal] tract, balloons have risk." But "the risk is not large," he said.

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Officials recommend health providers properly educate patients about risks and closely monitor them for potential complications, such as “acute pancreatitis and spontaneous hyperinflation.”

About 4 in 10 American adults – or nearly 40 percent – are obese, according to the latest federal government data. Obesity (defined as a body mass index of 30 or more) significantly increases an individual's risk of developing heart disease, diabetes and various cancers, making the condition a major public health concern.

Read the FDA alert at fda.gov.