An Adelaide mother has told of her fear, after she found out she was among 56 people told they were at risk of HIV or Hepatitis, after undergoing a colonoscopy at the Lyell McEwin Hospital, in Adelaide's northern suburbs.

Yesterday, the hospital announced one of its 16 colonoscopes tested positive to bacteria on October 6.

56 people had previously undergone colonoscopies, and had been notified by a letter and telephone call of the risks of the contaminated medical equipment which included contracting HIV and Hepatitis B and C.

A mother of seven, Michelle, was among those affected and notified, and told 7News she is now petrified of touching her children, and has a nervous wait of six months until tests for the diseases are complete.

"I put my kids’ dummies in my mouth, they pinch my toothbrushes by accident," she said, "It scares me."

"I had mine (colonoscopy) in July, it’s now October, I’ve done everything from July till October normal and then you get this."

"If I was to get one of those diseases from them, it’s going to affect my life, maybe my partner’s life and my kids life."

"It’s going to affect the other 55 people out there and their partners and their kids... It’s just wrong."

She said the incident has also made her lose faith in medical care at the hospital, her eight-year-old child is due to undergo an operation soon.

"If they can’t clean their stuff, what’s to say it’s not going to happen again?"

And she is furious about the way the distressing news was delivered, saying she received a phone call about the health scare, and then later a letter was delivered to her home.

"Why couldn't they known on each person's door to have a conversation about what went on." she said.

"They told me that I’d get some letters, and said something about bacteria," she said, "Then I received some paperwork, which gave me six months of blood tests."

"One now, one in three months and one in six months...Six months of worry."

But the South Australian health department insists the risk to the 56 patients is small, and that there has only been a handful of documented cases where Hepatitis has been transmitted during a colonoscopy, and none involving HIV.

"The clinicians who were involved in treating the patients actually made the calls personally," SA Health Chief Public Health Officer, Dr Stephen Christley said."

"Those doctors were very clear to leave a follow up number so that if people had concerns they could ring back."

"It’s a very difficult and complex communication when you’re communicating something that is actually a risk, but a very small risk."