Surgeons in Sao Paolo say they gave a 53-year-old man a kidney and part of the liver of his 26-year-old son.

The operation happened at the Hospital Israelita Albert Einstein two months ago.

The donor left hospital 10 days afterwards and his father was discharged eight days after that and is now back at work.

The operation raises ethical concerns about the limits of live organ donors and the medical risk to donors.

Self-regenerating

Writing in The Lancet, the doctors say: "This is the first report of a successful combined kidney and liver transplantation from a living donor."

Live liver transplants involve splitting the organ which can then regenerate itself.

Normally operations are done from an adult to a child.

But the doctors said the patient would have died if his son had not donated his kidney and a lobe of his liver.

They believe such operations should be done only as a last resort by experienced surgeons.

Live donor transplants have increased significantly in recent years because of a shortage of dead donors.

Moreover, they are thought to offer benefits to the recipient as dead donors tend to be older and their organs may have deteriorated over time.

As many as 50,000 people in Europe are said to be waiting for transplants and demand is growing by about 15% a year.

Balance of risks

John Evans, chairman of the British Organ Donor Society, said the operation was "quite exciting", but he would usually be against using live donors who were younger than the recipient.

Surgeons have complained of a crisis in organ donation

He said it was a question of balancing the risks and the benefits.

The death rate for live donors is about one in 3,000.

There have been a number of child kidney donors in the UK, but donating a liver lobe is more traumatic and risky.

Only about a dozen live donor liver operations have been done in the UK, said Mr Evans.

"It would be more stressful to donate a kidney and liver lobe at the same time. The shock to the donor's system would be greater," he added.

Donor deaths are often not linked to the transplant itself, but are due to a reaction to the anaesthetic or other factors.

Shortages

Some doctors have called for changes to the way the organ donor system works in the UK because of the crisis over organ shortages.

They want people to have an opt-out if they do not want their organs to be used for transplants, rather than the current system where organs can be used only with the consent of the donor or the donor's family.

But Mr Evans says this would undermine transplantation.

He believes it is better to educate the public about the benefits of organ donation and improve health professionals' awareness of how to keep patients alive when they are brain dead so their organs can be harvested.

And he calls for a change in the law governing hospitals' ability to keep patients alive artificially so their organs can be used.