The BBC's Richard Hannaford: The local authority says 100% accuracy is not yet possible

East Kent Health Authority and the NHS Litigation Authority fear the ruling could destroy the national screening programme.

They say the programme would find it near impossible to continue if the extremely high standards set by the court are to be met.

And they estimate an extra one million women a year would have to be called back for further tests - most of which would be unnecessary.

But the women's solicitor has said the appeal is a waste of NHS funds.

Smear blunders

Eight women died, 30 needed hysterectomies and more than 90,000 women had their tests re-examined after mistakes at the Kent and Canterbury Hospital between 1989 and 1995

The authority has paid more than a £1m to more than 47 women, but the three women were among 14 cases the authority had disputed.

Helen Palmer, Sandra Penney and Lesley Cannon, who won their case last month, said their lives were destroyed by the blunders.

They developed cervical cancer and had to have hysterectomies while they were in their 30s.

Saving lives

Figures from the Imperial Cancer Research Fund suggest the NHS Cervical Screening Programme prevents up to 3,900 cancers each year.

Doctors accept that no screening process is perfect and there will always be a margin of error - their task is to reduce that margin as much as is possible.

But last month's ruling demands too high a level of accuracy given today's technology, the litigation authority says.

The errors took place at Kent and Canterbury Hospital

Lawyers for the health authority and the hospital argued at the High Court that the women's smears were borderline. They said the screeners had made excusable errors in passing the slides.

The judge rejected this argument and said the screeners should have sent the samples for further tests.

Stephen Walker is chief executive of the NHS Litigation Authority, which is effectively an insurer for NHS Trusts.

He said: "We have no wish to prolong the suffering of the three women who brought this case against the Kent and Canterbury Hospitals Laboratory, but this judgement puts the whole screening programme at risk.

"It would demand a level of accuracy which present screening techniques cannot deliver.

"This appeal is not directed against the three women and we regret the continuing strain it will impose on them."

Amazement at the move

But Sarah Harman, the women's solicitor, said: "I am amazed at this decision.

"It has been made at the highest level and I am amazed in view of the fact that the Health Secretary Frank Dobson said a few months ago that NHS funds should not be used on litigation, they should be used for patient care."

She added that the appeal would dent confidence in the screening programme.

A spokesman for the Department of Health said: "The appeal is not being taken against the women. It is about protecting the screening programme."

Reduced risk, not a guarantee

Julietta Patnick is national co-ordinator of the NHS Cervical Screening Programme.

Julietta Patnick: More of a seatbelt than a vaccine

She said: "If this judgement stands, in order to be completely confident about all results, thousands of women would have to be recalled for further tests and probably unnecessary invasive investigations.

"The result would be that a programme which is designed to help women stay healthy would cause them physical and psychological harm.

"The NHS Cervical Screening Programme aims to reduce incidence and deaths from cervical cancer - it is doing just that."

Having a smear test every three to five years reduces the risk of developing cancer by 90%, she said.

"The screening programme must be viewed more as a seatbelt than a vaccine - if you wear a seatbelt there is no guarantee you won't be killed in a road accident but it lessens the risk."

Dr Jane Johnson, president of the British Society of Clinical Cytologists, said the standard set by the ruling would require an extra one million women a year to be followed up after routine smear tests.

At the moment, 500,000 women are called back because examination of their smear is inconclusive.

This can be because there is an abnormality or because the smear itself is contaminated by excess tissue.

Dr Johnson said the additional cost to the screening programme, which costs about £135m a year at the moment, would be incalculable.

And Dr John Toy, director of clinical research at the Cancer Research Campaign, said: "It is important that unrealistic expectations are not placed upon the screening programme, but women do have a right to a standard of care."

The Cancer Research Campaign is currently running trials on a new cervical screening test which has initially been shown to be 100% accurate.