Story highlights Insulin pens were erroneously used on multiple patients in a VA hospital, memo says

Shared items may have exposed 716 veterans to hepatitis B, hepatitis C and HIV

Incorrect use lasted from October 2010 to November 2012, memo says

Hundreds of veterans may have been exposed to hepatitis B, hepatitis C and HIV because of medical oversights that allowed insulin pens to be used on more than one patient at a Veterans Administration hospital in Buffalo, New York, according to a memo from the Department of Veterans Affairs to Congress.

"On November 1, 2012, officials at the (Veterans Affairs Western New York Healthcare System) reported that while conducting pharmacy inspection rounds on the inpatient units, they discovered that insulin pens intended for individual patient use were found in the supply drawer of the medication carts without a patient label on them," said the memo, obtained by CNN through the office of U.S. Rep. Brian Higgins, D-New York. "Although the disposable needles were changed each time it was used, the insulin pens intended for individual patient use may have been used on more than one patient."

"There is a very small chance that some patients could have been exposed to the hepatitis B virus, the hepatitis C virus, or HIV, based on practices identified at the facility," the congressional memo states. "(The health system) determined that all veterans who were prescribed the insulin pen during an inpatient stay from October 19, 2010, to November 1, 2012, should be notified."

The veterans' health care system has found that 716 patients may have been affected during this time period, Jim Blue, regional director of the VA's Office of Public and Intergovernmental Affairs, told CNN. "Veterans and their families will have an opportunity to speak with a nurse who will answer questions they may have and assist with managing followup care," Blue said.

However, slow patient outreach has also been a contentious issue.

"Beyond the fact that the error occurred at all, most concerning was the length of time it took the Buffalo VA to catch the error -- over two years, as well as the three-month delay in informing patients who may have been exposed," Higgins, whose district includes the city of Buffalo, wrote in a letter to the VA on Monday. "Also detail why affected patients weren't notified immediately."

Insulin pens are injector devices designed to allow multiple self-injections for one person, according to the Center for Disease Control and Prevention's website. Because blood may enter the insulin cartridge after injection, blood-borne pathogens can be transmitted from one person to another even after the needle has been changed. The devices are never to be used by more than one person.

"Unfortunately, since the day that new technology was introduced at the VA, they did not have a protocol in place that let the nurses know they were not supposed to use the cartridge on more than one patient," Republican U.S. Rep. Chris Collins told CNN affiliate WGRZ . Collins also called the situation in Buffalo "unacceptable."

The health system will continue to contact all people potentially affected by this issue, answer all questions, provide necessary information and help arrange blood tests or medical followup, according to the memo sent to Congress.

Higgins has also requested a detailed response outlining what steps will be taken to prevent any similar issues in the future.