New test for Down's 80% accurate

NEW tests for mothers-to-be, which tell more accurately if their babies are at risk of Down's syndrome, are to be rolled out across Scotland.

The tests will halve the number of mothers who have to undergo tests such as amniocentesis, which can result in miscarriage, because they are considered "at risk".

In particular, the tests will benefit older women, who are at greater risk of giving birth to a Down's Syndrome child.

The Scottish Government has spent 9.5 million between 2008-9 and 2009-10 introducing a range of maternity services, including the Down's syndrome antenatal scans.

Scans will be carried out at health boards across Scotland and the results will be tested in laboratories in NHS Lothian and NHS Greater Glasgow and Clyde.

The Nuchal Translucency scans can only be carried out during the 11th, 12th and 13th weeks of pregnancy.

Dr Graham Mackenzie, consultant in public health at NHS Lothian, which launched the tests yesterday, said: "This is good news for pregnant women and will increase accuracy in Down's syndrome screening significantly. Up until now, detection rate was 60 per cent; this will take it to above 80."

Previously, between two-thirds and three-quarters of women have requested the test, which took the form of a blood test. That proportion is expected to increase.

The NT scan works by measuring the amount of fluid lying under the skin at the back of the baby's neck - the greater the fluid, the greater the risk.

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Under the previous tests, about 270 women a year, out of 12,000 who fall pregnant in the Lothians, were considered borderline and required additional diagnostic tests, such as amniocentesis, which has a one-in-100 risk of causing a miscarriage.

As the new test is more accurate, that number is expected to be halved to about 135 a year.

Down's Syndrome babies are more common among older mothers and occur once in every 100 births to women aged 40, once in every 900 births to women of 30; and once in every 1,500 births to women aged 20 or younger.

Lynn MacKenzie, NHS Lothian ultrasonographer superintendent, said: "The fact that this test is more accurate means fewer women will have to go through invasive testing and we will have fewer miscarriages."

A Scottish Government spokeswoman said: "It is good news that the new nuchal transparency test is likely to reduce the number of women who choose to have an amniocentesis, as it is a more accurate test."