Katie Widdowson hurt her wrist while being tied up during an erotic encounter earlier this year.
The 24-year-old was rushed to hospital in agonising pain after the incident however was dismissed by medics.
Just 24 hours later, she died in an ambulance.
The mum-of-one’s left hand had turned black and the painkillers given to her by doctors did nothing.
She was a victim of rare disease Necrotising Fasciitis, an inquest has heard.
Katie is thought to have contracted it while in a sex game with partner Dean Smith.
taff at Good Hope Hospital in Sutton Coldfield were found to have failed to correctly diagnose her.
Mum Patricia confirmed the circumstances of her daughter’s death.
She said: ‘Katie and Dean had been at a New Year’s Eve party until 5am on New Year’s Day.
‘They’d got home around 6am and they’d had sex and she was tied up. They were a loving couple and it’s nobody’s else’s business what they did behind closed doors.
‘Later that day Katie sent Dean a photo of her wrist saying it was hurting.
‘The next night her arm looked horrific. Dean took a picture of it while the ambulance was on its way.
‘There is a black mark on the base of her thumb and we think that is where the injury started.
‘I don’t know what caused the injury but it doesn’t matter because that was not what killed her. The hospital’s complete and utter neglect killed her.
‘When she went into Good Hope Hospital on the 1st she had a MEWS (Modified Early Warning Score) of six which is a red flag for sepsis but this was ignored.
‘The junior doctor had only been in the country for four months. She had come over from India. If they had treated Katie properly she would still be alive.’
Katie should have been kept in hospital and undergone major surgery, according to assistant coroner Emma Brown.
During the inquiry at Birmingham crown court, Katie’s former partner Dean revealed he had tied her up.
The 25-year-old chef said: ‘I do not remember much about it. It’s not anything we have ever done before.’
The family are now considering taking legal action against Heart of England Foundation Trust which runs Good Hope.