A sick little boy is looking forward to a new lease of life after his father was given the go-ahead to donate one of his kidneys to him.

Five-year-old Ryan Siddall, whose kidneys are failing, and his father Ian, 42, will undergo surgery at St James's Hospital in Leeds within the next five months.

The youngster's mother and Ian's wife, Rose, 43, said the news was "brilliant but scary."

"My big man and little man are going under the knife and I have to think about the worst as well as the good," she said.

"I am scared to death but it was great when we got the news that Ian was a match. It has been hard dealing with Ryan's illness and we have the hardest road to go down now but we are a close family and we will get through it.

"I think Ryan will come out of this quickly because he is a fighter."

Ryan is a miracle baby for the couple, who live in Buttershaw.

A scan carried out when Mrs Siddall was 22 weeks pregnant showed that his kidneys were larger than normal.

Doctors found he had a blockage in his urethral valves which prevented him from passing urine.

This was causing a build-up in his kidneys and damaging them and they were told that if they carried on with the pregnancy their son may die at birth.

The devastated couple were given a stark choice - to let nature take its course, to attempt to carry out a bladder-shunting operation in which a fine needle would be inserted through Mrs Siddall's stomach to drain the fluid from Ryan's bladder or to terminate the pregnancy.

After much soul-searching they decided that going through the pregnancy only to lose their baby would be too much to bear and although distressed by the decision they opted for termination.

However, when the couple returned to hospital for the operation a scan to find out the position of the baby showed the blockage had cleared.

The operation was cancelled immediately and Ryan was born naturally at 35 weeks, weighing 6lb 6oz. However, the blockage required an operation and left Ryan with permanent damage to his kidneys.

"I still call him my miracle baby because that is what he is," said Mrs Siddall.

"He has fought all this way and proved doctors wrong. He will do it again. We know that it is not going to be a bed of roses but we are both positive about the future and our main priority is Ryan."

Although Ryan has grown into a lively little boy who is doing well at his school, Buttershaw Primary, his kidney problems mean he has spent a lot of time in hospital and is prone to infections because of a poor immune system.

In the last year he has had four bad viral infections and it became clear that a kidney transplant would be the only way forward for Ryan.

He has been on the transplant list since December waiting for a kidney but doctors also asked Mr and Mrs Siddall if they would be prepared to donate a kidney.

They both agreed and underwent extensive testing to see who was most suitable. They even went on a strict diet - with Mr Siddall losing two stone - to make sure they were healthy enough to go through with an operation.

Scans showed that Mrs Siddall's kidney's were bigger than her husband's and she also had two tubes coming from them, which would make it hard for the surgeons.

When tests showed Mr Siddall was a suitable match, the family decided to go ahead with him giving a kidney to Ryan.

The donated kidney could last eight years but the family has also been warned that when Ryan goes through puberty it could fail. He would then need a further transplant.

Surgeons will use keyhole surgery to perform the operation and it will take three months for the pair to recover and Ryan will not be able to attend school for at least six months.

"We know there will be danger points in the first three months," said Mrs Siddall, who will stay at charity-funded Eckersley House which provides accommodation for families while their children are in hospital in Leeds.

But they are looking forward to seeing an improvement in the quality of life for Ryan. "I can't wait to see him eat a proper meal," said Mrs Siddall, who still has to feed Ryan special milk through a tube and make sure he takes a variety of medicines daily.

The youngster also suffers pain in his legs from mild bone disease caused by his kidney problems and he gets tired easily.

"Ryan does understand what is happening," said Mrs Siddall. "He comes to transplant meetings with us and we have explained that he is getting Daddy's kidney.

"I think he will cope very well."

There is a chance a kidney could become available from the donor register before the planned operation but Mrs Siddall said she would prefer it to be her husband.

"It is awful because we are basically waiting for someone to die, which is sad," she said. "I would like it to be Ian because we know it is a perfect match."