A mother-of-three died following a routine procedure to remove a gallstone.
A verdict of medical misadventure was returned at the inquest into the death of Patricia Bishop, of Slievebloom Road, Drimnagh, Dublin 12.
Mrs Bishop (66) loved sea water swimming and was fit and healthy when she was admitted for the procedure at St James's Hospital on September 22, 2016.
She planned to travel to Wexford to go swimming the following day but instead of being discharged as expected, she became critically unwell and was transferred from recovery to intensive care.
Mrs Bishop developed sepsis due to a perforation of bowel tissue during the procedure and died eight days later on September 30.
Dublin Coroner's Court heard that her doctor had "never before seen a case of sepsis like this".
Finbar McCarthy, consultant gastroenterologist and physician at St James's Hospital, said he hopes never to see a case like it again.
He was removing the stone from the woman's gall bladder ahead of a planned removal of the gall bladder.
He said Mrs Bishop experienced some discomfort after the procedure but felt at the time this was normal.
"When I examined her the following morning at 8am, her heart rate and blood pressure were normal and she had no fever. These are the early warning signs for sepsis," Mr McCarthy said.
Three hours later, her condition deteriorated so rapidly that she was transferred to intensive care.
Her husband, Tom Bishop, said she was not well hours after the procedure and was having trouble breathing, but he was told to go home.
"The next day I went in to see her, but by 11am they were taking her in to intensive care and that was the end of my wife. I was told to bring in the family," Mr Bishop said from the public gallery.
Mr McCarthy described the bowel as a barrier system to prevent harmful bacteria entering the body.
A breach of this barrier, such as a perforation, can allow dangerous bacteria to enter the system and "create havoc", he said.
"She wasn't matching up with what you would expect to see in somebody in her condition," he said of her initial post-procedure condition. As a result, Mrs Bishop developed an overwhelming form of sepsis that led to multi-organ failure.
"There was a period where things were being held together, but then it was like a dam broke. I have never seen anybody get so sick so quickly," Mr McCarthy said.
A post-mortem report by pathologist Dr Kate Dineen gave the cause of death as multi- organ failure due to sepsis due to a complication of endoscopic retrograde cholangiopancreatography (ERCP) to remove a gallstone.
Coroner Dr Myra Cullinane returned a verdict of medical misadventure and offered condolences to the family.