A Birmingham hospital is pioneering an operation that can save an unborn baby being drained of life by its twin.

The city's Women's Hospital is one of three in the UK that carries out complex operations like the Twin Reverse Arterial Perfusion (Trap) that was performed on Sarah Garratt last month.

Now Professor Mark Kilby, professor in maternal and fetal medicine - who has carried out five Trap procedures since 2004 - is leading a study into treating congenital urethral obstructions in unborn baby boys.

The rare condition, in which the foetus is unable to dispose of waste, affects about one in 3,000 pregnancies.

It can result in babies being born "dry" with no fluid around their bodies and lead to kidney failure.

In 40 to 60 per cent of cases the condition can prove fatal.

A randomised trial, funded by Wellbeing of Women and set to continue until 2008, is being conducted to assess whether inserting a "ponytail" catheter into the baby's bladder would benefit most cases.

The device remains in the womb and is removed when the baby is born.

Prof Kilby said: "We're looking at ways of treating more babies' conditions in the womb, and at this point in the study we're looking at which babies benefit best from this procedure.

"Although cases like this are rare, we are involving most fetal medicine centres across the country in this research."

Birmingham Women's Hospital is one of just three specialist centres in the UK - the others are Kings College and the Queen Charlotte Hospital in London - that performs pioneering operations on unborn babies with rare conditions.

Since August 2004, experts at the hospital in Edgbaston have operated on about 60 mothers whose babies have developed twin-to-twin transfusion syndrome (TTTS), which affects about one in 3,000 naturally conceived, identical twins.

Instead of using traditional surgical instruments, surgeons use laser and keyhole technology to "zap" or seal shared blood vessels in the afterbirth which leads to one twin becoming much stronger than the other.

The risk of this condition is in part linked to the likelihood of twins being conceived naturally.

It does not affect twins born as a result of fertility treatment where individual embryos are implanted in the womb. Between one in 50 and one in 80 British women are likely to conceive twins, but for women in Nigeria that ratio is one in 15, and therefore they face a heightened risk of TTTS.

Prof Kilby is now looking at treating the condition using radiowaves, negating the need for any surgery, but he pointed out such treatment was still at an "experimental stage".

He added: "Mothers with this condition often feel over-bloated and much bigger than they should be at 18 to 20 weeks, which is when it is often detected during ultra-sound scans.

"In the days before ultra-sound, by 24 weeks 90 per cent of babies with TTTS would miscarry, only a few would survive, and around half of those would be handicapped.

"But we're now able to drain the excess fluid from around the stronger twin by inserting a needle into the baby's sack in the womb.

"This has enabled us to establish a 75 per cent success rate using this technique, and there is only a five per cent risk of a twin developing cerebral palsy.

"There are clear advantages of using this technique.

"However, the instruments are being used inside the womb and whenever you do that there is a risk of miscarriage." ..SUPL: