Menstuff® has compiled information on the issue of the early
detection of Down Syndrome.
Early warning over Down's
risk
Safe test for Down's
syndrome
Early warning over Down's risk
At the moment the test is only offered in one London hospital, but doctors say other hospitals are already expressing an interest.
Oscar - the one-stop, counselling, assessment and risk clinic - enables pregnant women to be checked two months earlier than normal, at 11 weeks.
Women then identified as being at high risk can have follow up tests, which will allow them to decide much earlier whether or not to opt for abortion.
We can identify problems much sooner than by using the conventional approach
Abnormalities
The test, which is currently offered at the Harold Wood Hospital, in Romford, East London, can also pick up other chromosome abnormalities and whether the un-born baby is suffering from cystic fibrosis.
It was built on scientific and technological breakthroughs made over the last decade including analysis of the levels of a compound called free beta HCG in the placenta and checks for pregnancy associated plasma protein A. Women will be able to have their results when they leave the clinic
Dr Kevin Spencer, the consultant biochemist at Harold Wood, who developed Oscar along with specialists from King's College Hospital, London, said the test was relieving anxieties for many pregnant women.
Women coming to the clinic have a blood test to assess the risk of their having a child with a genetic disorder and while they are waiting for the results of these bio-chemical markers they are offered a nuchal fold ultra-sound scan which looks at the fluid-filled area behind the foetus's neck.
"We are offering screening to women of all ages at 11 weeks of gestation using the nuchal fold test and bio-chemical marker tests.
"By doing this we can identify problems much sooner than by using the conventional approach.
"Following a one hour visit to the hospital the patient can go away with the reassurance that their pregnancy is fine, but a small number of women will have to consider further diagnostic tests.
"Only 3% of the women we have coming here chose not to have the test."
Speedier diagnosis
He said that conventional testing meant some women have to wait until as late as 21 weeks into their pregnancy to decide to terminate their babies.
His programme allows women to make a decision on whether to terminate at as little as three months, meaning less emotional and physical risks for the women.
Dr Spencer said:"In our screening programme we test and give the patients the test results within an hour. "For those few women where there is a problem they can be dealt with speedily.
"Those needing invasive tests can be given them the following day and two days later they will have their results."
Over the last three years 13,000 women attending antenatal clinics at the hospital have been given the test.
Fifty were identified as having a substantial risk of having a baby with a genetic disorder and all chose to have termination following counselling.
The new system is said to be able to spot 90% of foetuses with Down's compared to 70% previously.
Patient Barbara Fryer who has had the Oscar test said the early results allowed women like her to make informed decisions about their pregnancies.
"If you are going to have a Down's, or have a high risk of having a Down's, baby you can prepare yourselves for what you have got to do in order to look after the baby."
If the test is successfully developed it would provide doctors for the first time with a way to diagnose Down's syndrome without having to carry out a potentially dangerous internal procedure.
At present, techniques such as amniocentesis and chorionic villus sampling, which both involve removal of tissue from the developing foetus for analysis, pose a significant risk both to the developing child and to the mother.
The breakthrough has been made by a team from the Chinese University of Hong Kong using a technique called fluorescence in-situ hybridisation (FISH).
This involves using coloured markers to identify the presence of genetic material called chromosomes.
Normal individuals have two copies of chromosome 21, whereas people with Down's syndrome have three.
Plasma samples
The researchers used the technique to test plasma samples obtained from three women carrying foetuses affected by Down's syndrome.
They were able to identify foetal cells with three chromosome-21 signals.
The results were compared to samples taken from seven foetuses who did not have Down's syndrome.
The researchers are confident that their results show that it should be feasible to develop a non-invasive test.
They recommend that future large-scale trials should be initiated to assess the diagnostic accuracy of this method.
Sarah Waights, from the Down's Syndrome Association, said the test might help some prospective parents, but only if accompanied by sufficient counselling.
She said: "The problem with pre-natal testing is that it is so often carried out without proper counselling and support for the parents and therefore often leads to big grief."
Source: The research is published in The Lancet medical journal. Article has been removed from the www.getsmart.com web site
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