Deborah O'Hara underwent an operation to remove a 8.7in (22cm) tumour at Coventry's University Hospital in 2015.
A clip was inadvertently placed on one of her arteries which led to a lack of blood to vital organs. She died two days later.
Deputy coroner Emma Witting recorded a verdict of death by misadventure and said it was a "tragic loss".
At the inquest in Coventry, surgeon Anthony Blacker told the hearing it was a complicated operation over six hours and when the tumour was removed Mrs O'Hara lost five litres of blood.
In a bid to save her life, four clamps were placed on her arteries, but the move cut off the blood supply to her bowel and she died.
Bosses apologised after her family learnt about the mistake from the BBC.
Widower Andy O'Hara said there was a degree of justice in getting the cause of death recognised saying it was "another bit of closure, but there's still a lot of unanswered questions".
"I'm gutted for my family because we've lost a lovely wife, brilliant mum," he said.
University Hospitals Coventry and Warwickshire NHS Trust previously apologised to Mrs O'Hara's family after failing to tell them about the error.
An internal investigation has been carried out.
It is understood the hospital will pay compensation.

Belfast man Frampton, 28, outpointed Scott Quigg on Saturday to add the WBA world title to his IBF belt.
On Wednesday, WBA bosses said that their former champion Rigondeaux, 35, must be Frampton's next opponent.
Frampton's manager Barry McGuigan has consistently ruled out the Cuban as a possible opponent for his fighter.
"He's amazing on the back foot but he's negative," McGuigan said of Rigondeaux, who fights Briton Jazza Dickens in Liverpool on 12 March.
"What do we gain by fighting him?"
McGuigan's view is that Rigondeaux, who was stripped of both the WBO and WBA belts last year for inactivity, brings little to the table in terms of television or fan appeal.
After Rigondeaux was stripped of the title, the world governing body promoted Quigg from interim WBA super-bantamweight belt holder to champion.
However, the WBA have now said that unbeaten Rigondeaux's "impressive record and accomplishments" mean that he must be Frampton's next opponent.
The WBA said it was "honoured" to have Frampton as its champion, adding: "We congratulate him on a performance that was as intelligent as it was effective."
In spite of the WBA's directive, it is far from certain that Frampton will agree to the Rigondeaux fight, so there appears a strong possibility that the Northern Irishman may give up the WBA belt.
After Frampton's win on Saturday, McGuigan said that a contest with Mexico's WBA featherweight champion Leo Santa Cruz was an "obvious fight".
Rigondeaux has won all 16 of his professional bouts.

Newcastle-based Out of the Kitchen had denied the unauthorised sale of nitrous oxide, also known as "laughing gas", through its Toon Whip brand.
Although it is used legally in the catering industry, it can be fatal when used as a drug.
The case followed an undercover investigation by the BBC in which a reporter was sold two canisters.
Toon Whip advertised a "whipped cream delivery service", but the reporter was given instructions by the firm's staff on how to inhale the gas using a balloon.
Newcastle Magistrates' Court heard Out of the Kitchen Limited made a profit of £40,000 in 2015-16, with £10,000 of that figure coming from Toon Whip.
The fine must be paid within 14 days.
Directors Jonathan Lawrence, 30, of Stamford, and David Jenkins, 29, of Newcastle, are also charged with the unauthorised sale of nitrous oxide.
They have entered not guilty pleas.
The case against them was adjourned until 23 January.

24 July 2017 Last updated at 14:56 BST
He's been racing sharks... Yes, you read that right.
Michael Phelps had a special shark suit to help him compete against the ocean predator.
And don't worry - he actually wasn't in the water with them, it was done with special effects.
Watch this to see who was the fastest...
Pictures courtesy of Discovery
An inquest into the death of a mother-of-three after an error during surgery has recorded a verdict of misadventure.
[NEXT_CONCEPT]
Carl Frampton must fight Cuban Guillermo Rigondeaux by 27 July to avoid being stripped of one of his two world super-bantamweight titles.
[NEXT_CONCEPT]
A catering firm has been fined £7,620 for selling gas used as a recreational drug.
[NEXT_CONCEPT]
Olympic superhero Michael Phelps is one of the fastest swimmers on Earth, but he's been taking up a pretty weird challenge.