A widow died on the operating table when a surgeon tried to remove a liver instead of a kidney in a fatal mix-up, an inquest has heard.
Retired accountant Amy Francis, 77, of St Julians, Newport, South Wales, died of internal bleeding and heart trauma despite urgent efforts to save her.
Consultant urologist Dr Adam Carter relived the moment he discovered his fatal mistake today in a candid retelling of his error.
Relatives of the pensioner listened in silence at the inquest in Newport and afterwards praised Dr Carter for his honesty.
Son Alan Francis, 52, went on to wish him well for the future and praised the hospital for "owning up" early to the error.
Mrs Francis underwent keyhole surgery to remove a cancerous right kidney at the Royal Gwent Hospital, Newport, on July 21, 2010.
Cancer in her left kidney was less serious and was due to be treated after she had recovered from the routine surgery.
Dr Carter explained that tiny cameras are slid inside small incisions below the ribs in a technique known as keyhole surgery.
Once the kidney is located, a larger incision is made lower down allowing the surgeon to put his hand inside and simply pull it out.
The second incision prevents continued use of cameras and means the procedure is done "blind", using sense of touch and experience.
Dr Carter said the removal is the easiest part and he asked a trainee present, who had never done it before, to carry it out.
She felt inside the cavity but was not confident enough to remove the organ and Dr Carter took over himself.
He said it was possible that while she was manipulating the organ the thin membrane protecting the liver, the peritoneal sac, was breached.
"I think that what happened is that the peritoneum had been breached and the liver fell down and became more accessible than it usually is."
He added that the kidney may well have been pulled down out of place as well.
"I put my hand inside and felt an organ and I pulled it," he said.
He was immediately told by the anaesthetist that the patient's blood pressure was dropping and he realised his mistake.
Two senior surgeons were called to the scene and every effort was made to save Mrs Francis, but they were not successful.
Dr Carter said as a result of the death operating procedure had been modified slightly and the new method communicated "worldwide".
He said he had carried out the procedure 20 times since the death without a problem.
David Bowen, the coroner for Gwent, recorded a narrative verdict after formally summarising the facts of the case.
"Whilst undergoing keyhole surgery for the necessary removal of the cancerous right kidney, Mrs Francis's liver was ruptured when it was mistakenly and unintentionally identified as the kidney and was catastrophically torn and damaged, resulting in death," he said.
Son Alan Francis said before the inquest finished: "We accept the decision and we also accept that Mr Carter and his team acted in good faith to prolong my mother's life.
"We also appreciated his honesty and wish him well for the future and hope he goes on to do other successful operations."
Outside he added: "We appreciated Mr Carter's honesty and him coming along here today and hope that we can put it all behind us now.
"I think that it was the honesty that saved the hospital. If we thought that they had not answered our questions it would have been different. This was an honest mistake."