A Jehovah's Witness died in a Sheffield hospital after refusing a blood transfusion for a hysterectomy.
Alison Mallinder, aged 44, suffered complications during surgery at the Royal Hallamshire Hospital and died five days after the operation.
Mrs Mallinder, of Mansfield Road, Worksop, only mentioned she was a Jehovah's Witness the day before her operation, and refused to be given blood products, a Sheffield inquest heard.
She had decided to have a hysterectomy after suffering years of abdominal pain.
Professor of reproductive surgery and medicine Ti C Li said: "She did not want to make a fuss about the fact she was a Jehovah's Witness which is why she had not mentioned it until the day before the operation.
"I asked her if she wanted to go on because of the increased risks, especially if there was significant bleeding. But she was clear in her mind that she wanted to get on with the operation. Having satisfied myself that she realised the risks, we proceeded with the operation ."
Prof Li said it was rare for a blood transfusion to be needed during a hysterectomy but he did the operation himself, instead of a junior. He discovered some of her abdominal organs were stuck together as a result of a previous operation.
Four surgeons worked for three hours to separate them. Mrs Mallinder suffered heavy bleeding and a tear to her small bowel, which was repaired.
Heavy bleeding led to a severe drop in levels of haemoglobin, which carries oxygen to major organs. She was put on a ventilator in intensive care and given drugs to try to counteract blood loss, but died on June 11.
Coroner Chris Dorries gave a narrative verdict that Mrs Mallinder died after suffering complications during and after surgery "and the subsequent treatment regime against a background of refusal to accept blood products".