LA JOLLA, Calif. -- Anyone who has had gastric bypass surgery at Scripps Hospital in La Jolla may be at risk of having hepatitis or HIV, 10News reported.

For more than a year a nurse at Scripps La Jolla was not properly sterilizing a surgical instrument called a gastroscope.

Nearly 300 patients who had surgery with that nurse are being offered blood-disease screening tests.

"While there is a small, very small, risk of developing blood-borne diseases like HIV or hepatitis -- that is a risk. We've been reassured by the national experts that those risks are extremely low," Chief of Staff Dr. Dana Launer said.

The nurse -- who has since been fired -- disinfected the gastroscope after each use, but failed to sterilize it according to hospital procedures.