The 3cm dental file dropped into Vanessa Snary's mouth as she underwent a routine root canal surgery at Oldbury Court Dental Centre in Fishponds.
Her ordeal began after the dentist 'didn't offer a mouth guard' for the treatment, before the file accidentally fell into her throat.
The trauma intensified when, instead of calling an ambulance, staff allegedly told Vanessa to wait in the surgery's reception – before Dr Ester Torrejimeno drove her to A&E herself.
Doctors immediately rushed Vanessa for X-rays and dosed her with strong painkillers, then performed surgery to remove the ultra-sharp tool from her stomach.
Insult was then added to injury for Vanessa, who said after surgery she was told by her employer her contract would be terminated 'due to [her] sickness level'.
Vanessa, aged 29, told the Bristol Post: "[The dental file] was knocked out of my mouth and I started to choke, so then approximately five or six members of staff were called into the room – dental nurses, dentists, reception staff.
"They just watched me choke on it and no ambulance was called.
"Following choking my body had pushed it down and it reached my stomach and was stuck. Nobody at this point had called for an ambulance."
Vanessa said she urged staff to call 999 but was instead driven to Southmead Hospital by Dr Torrejimeno, a journey which took 25 minutes.
X-rays revealed the dental file became lodged in her upper stomach and it emerged the tool had pierced Vanessa's insides, leaving her in intense pain.
Doctors were forced to give a 'cocktail' of drugs to ease the pain, before performing surgery the following day to remove the file.
Reliving the ordeal, which happened on Tuesday, November 8, Vanessa said she 'didn't feel' the file because she was under local anaesthetic to numb her mouth.
"I didn't really feel it hit the back of my throat," she said.
"I realised I was choking on something. It happened very quickly. It was extremely frightening – I didn't know what I had swallowed.
"I didn't know until she made me aware and showed me what I had swallowed, which is when the panic kicked in."
Vanessa's ordeal was so shocking that experts from wards across Southmead Hospital visited her room to ask about what happened, she said.
"It's not something they had come across before," she said.
She claims things got even worse when she received a phone call after surgery from her employer's human resources department, advising her of a 'termination of contract'.
Vanessa, who had started as a helpdesk manager at Linaker Facilities Ltd on August 30 and was still in her probation period, claims they told her 'it was due to the needs of the business, because of the time I have taken off'.
"I was gobsmacked about the fact that they thought it was okay following major surgery to give this news," she said.
Linaker's managing director, Bill Harrison, said the company can't elaborate on the reason Vanessa's contract was terminated because of data protection law.
He said external HR consultants are sometimes used, adding: "I'm very confident that would not have happened."
Vanessa is now left with injuries to her stomach and voice box, and the damage caused as the file went down her throat left her unable to speak for nearly a week.
"I was on nil by mouth (unable to eat solids) in my own bedroom away from everybody, given lots of different drugs and cocktails," she said.
"I was quite heavily sedated so I didn't move and was effectively pain free."
Vanessa, who lives in St George with partner Mark Gallop, 44, added: "I didn't expect this to happen, especially from a well-known dentist with such a high reputation and given the fact that this is only my third appointment with them as a relatively new patient.
"I was always made to feel at ease there.
"To me it's a freak accident that should not have happened and it was not dealt with in the right way either."
After the operation Vanessa said Dr Torrejimeno tried to phone her about '10 times' to check she was okay, but added she was too traumatised to take the calls.
She said she had also awoken after the surgery to a card and flowers from Dr Torrejimeno, which was 'very distressing'.
Vanessa said: "These are professionals trained to be able to deal with emergency situations. I still can't understand why I wasn't taken to a hospital in an ambulance."
Dr Torrejimeno, who is self-employed and was working from the Oldbury Court practice, said it was 'an unfortunate incident'.
"I would like to apologise once again to Ms. Snary that the treatment did not go as expected," she said.
"I always aim to provide the best possible care to all patients and have taken steps to ensure that something like this does not occur again."
Vanessa has now restarted root canal treatment at Oasis Dental Care in St George.
She said: "They did a marvellous job. They knew what happened and they were very understanding, very reassuring, they explained things to me and used the proper procedures and they were just fantastic.
"It took a lot of crying and a lot of reassurance from my partner [to undergo more treatment] because mentally I had been through quite an ordeal.
"Future dental appointments are going to be quite traumatic for me."