The operation was halted when the error emerged

Hospital staff gave three units of incorrect A negative blood to 77-year-old retired builder Graham Davies because there was another patient with the same name.

But the inquest in Cardiff heard that Mr Davies - originally admitted to Newport's Royal Gwent needing an emergency transfusion - was later given type O positive blood after he was confused with a patient with the same name.

The coroner recorded a verdict of natural causes after concluding there was no proof the transfusion had caused his death.

The error was only spotted halfway through emergency surgery at Cardiff's University Hospital of Wales, and Mr Davies died on the operating table.

The blood was prepared for the other patient. There was a human error made Dr Helen Thomas

Consultant haematologist Dr Helen Thomas told the hearing that a blood compatibility form had to be filled out with each patient's details when a transfusion was needed.

An order for 10 units of blood for Mr Davies was phoned to the laboratory, and one of the two scientists in the lab made a note of the patient's name and hospital number.

But a complication arose because there was another patient also called Graham Davies - but with a different middle name.

"The second scientist checked for the blood in the lab and found the sample for the other Mr Davies," Dr Thomas said.

"As a result the blood was prepared for the other patient. There was a human error made."

Mr Davies was then transferred - with the wrong blood - to the University Hospital of Wales in Cardiff for a specialist to operate on his ruptured aneurism - a bursting of the heart's main blood vessel.

Telephone call

Consultant Dr Ian Apperdurai told the inquest that they had a phone call mid-operation from the Royal Gwent after lab technicians realised the error during checks.

"The first I knew of it was when we had a phone call to say it was the incorrect blood," he said.

"I stopped the blood transfusion immediately and sent to the lab for some O negative blood which is the safest to give. But Mr Davies died during the procedure."

Vascular surgeon Dr Tudor Davies told the court the operation's survival rate is very low - and elderly Mr Davies, of Oakdale, south Wales, only had a small chance of survival.

Cardiff Coroner Dr Lawrence Addicott said it could not be proved that the incorrect blood transfusion directly led to Mr Davies' death.

"It has not been established that the transfusion played a part of any significance," he said.

"There has been an inquiry at both hospitals with regard to the occurrence of miss-matched transfusions. I will make reports to both.

"Situations like this must be reduced in the future."

A statement from the trust said a thorough investigation had been carried out and a full apology had been made to Mr Davies' family.