A mum is suing after her newborn son was breastfed by a total stranger.

A US mother is suing a hospital in Minnesota after a stranger unwittingly breastfed her newborn son back in 2012 after maternity ward staff accidentally mixed two babies up.

Tammy Van Dyke is seeking US$50,000 (AU$67,100) in damages for hospital negligence following a mix-up that saw her two-day-old baby, Cody, placed in the care of another woman with twin newborns on December 5, 2012. It was in this unnamed woman’s care that Cody was breastfed, as she believed he was her son Liam.

According to the Minneapolis Star Tribune, the lawsuit launched last week said the mix-up led to “unnecessary medical treatment, tests and expenses, and severe mental injury and emotional pain and suffering.”

Days after the mix-up, both Cody and the unnamed woman were forced to undergo rigorous bouts of testing to ensure they were not exposed to infectious diseases like hepatitis or HIV. Cody then was re-tested for the same diseases every three months for a year following the incident.

In an interview with KSTP-TV following the 2012 incident, Van Dyke said she initially had such faith in the hospital and its practices.

“In good faith you drop your child off at the hospital nursery with the nurses,” Tammy told KSTP-TV. “Never in a million years would you think this could happen or would happen.”


Image: Screenshot/ABC News' KTSP-TV.

The hospital has since amended its processes and acknowledged their mistake, saying they have implemented a new procedure that uses high-tech identification bands to avoid an incident like this one happening again.

"We began using electronic identification bands for the mother and infant that must be matched when returning the infant to the mother," said Michelle Smith of the Abbott's Mother Baby Centre.

"This helps us to assure that the identity of the infant and mother are matched each time."

It is understood there have not been any further mix-ups since the implementation of the new technology.