Down's test: A mother's right to choose

The latest test for Down's is up to 98 per cent accurate and costs the NHS just £25. So, asks Annalisa Barbieri, why isn't it offered to all pregnant women?

When I was pregnant with my first child, in 2003, I had little clue about the efficacy of the screening tests one is offered. When I was booked into University College Hospital, my midwife mentioned something called the integrated test for Down syndrome (UCH introduced it in February 2003).

At 12 weeks, I duly went along for a scan where the nuchal fold of my developing baby was measured; I gave some blood. At 15 weeks, I went back for more blood tests. The one thing I remember clearly was being told that the integrated test gave you no results until at least week 16 – that was the disadvantage – but that it was more accurate than any other non-invasive test offered.

At about week 17, I got a letter: my odds for having a baby with Down syndrome were less than one in 50,000. I'd never heard of such odds, and neither had anyone I talked to. "Wow," everyone said, "but you're 36." (I was 37 at the time of giving birth, the age they take into account).

Soon after, I joined the world of internet chat-rooms and began to realise that very few women had heard of – or been offered – the integrated test. Most were offered a blood test, maybe a nuchal fold scan: the triple test or the quadruple test, occasionally something called the combined test. Some, horrifyingly, were given odds based only on age (this is only 32 per cent accurate). They were given odds that confused them, and gave them days of worry: should they have an amniocentesis or chorionic villus sampling (CVS), the conclusive, but invasive, tests that carry the risk of miscarriage?

This month, reseachers at Stamford University in California said they had devised a blood test for Down syndrome, which could be available in five years. But last month came news that too many healthy foetuses are dying after unnecessary amniocentesis and CVS: in preventing the births of 660 babies with trisomy-21, 400 foetuses that didn't have it are miscarried. The Royal College of Obstetricians and Gynaecologists stands by the accepted risk of between 1 and 2 per cent in having such procedures. Whatever the reality, it raises a question: why isn't every woman who wants it offered the integrated test?

At this juncture, I must make an important point. This isn't about finding a test so accurate that no children with Down syndrome, or trisomy-21, will ever be born. It's about giving parents who want it as accurate a picture as possible so they can make an informed choice and not frightening them into having invasive and perhaps unnecessary procedures such as amnios and CVS.

Let's take the tests in turn. The first was the double test. This took maternal age into account as well as looking for two blood markers: alpha fetoprotein (AFP) and human chorionic gonadotrophic (hCG). AFP tends to be decreased in Down foetuses, hCG increased. It has a 59 per cent accuracy rate: that is, it picks up 59 per cent of babies affected. The triple test added another marker to the blood test, uE3, which tends to be decreased in affected babies. Its detection rate is 63 per cent. The quadruple test added a further marker, inhibin A, which tends to be increased in foetuses with trisomy-21; the quad test is picks up 72 per cent of affected babies.

After this came the combined test, which added to the blood tests by combining data from a nuchal fold scan (which must be done between 11 and 13.6 weeks). Research had found that the thicker the nuchal fold the more likelihood of a baby having Down syndrome. (New markers now also look at other markers such as the presence of the nasal bone – the sooner this is visible, the less likelihood of the syndrome – and the tricuspid valve flow through the heart.) The combined test is said to be 76 per cent accurate. The nuchal test (NT) on its own is only 69 per cent accurate, but relies heavily on the skill of the sonographer.

Then came what should be the industry standard: the integrated test. This combines maternal age, NT result, one blood test at about 12 weeks that looks for PAPP-A (pregnancy associated plasma protein A) and another blood test at 15 weeks that looks at further biochemistry: AFP, hCG, uE3 and inhibin-A. At worst, it has an 89 per cent detection rate, at best 98 per cent (it is more accurate the older the mother is). Put personally, at 37 I had a risk of 1:200 vs the less than 1:50,000 the integrated test gave me. At 42, I had a risk of 1:55 vs 1:1,900.

Crucially, the integrated test cuts the number of false positives right down, and the cut-off point for screen-positive odds (after which women are advised to have an amnio) is 1:150 for the integrated, compared to 1:250 for the others. The bottom line is that if women have screening tests with a low rate of accuracy, the reality is that they are more likely to opt for invasive tests that put their babies at risk.

Only two hospitals currently offer the integrated test on the NHS, St Mary's and UCH (my investigations tell me that UCH will cease to offer the integrated test routinely next month, but it had not confirmed or denied this at the time of going to press). Women can opt to have it done privately at a cost of about £170 (it would cost the NHS much, much less), but even then it often involves travelling large distances.

Why isn't it industry standard? Pat O'Brien, obstetrician at UCH and spokesperson for the Royal College of Obstetricians and Gynaecologists, says it's largely to do with "expense [of the scans; not all hospitals offer scans at 11-13 weeks] and training". It takes an extra day to train a sonographer to do an NT, but there is a huge shortage of sonographers. A further setback was that, in March, NICE published guidelines recommending the combined test, partly, one can imagine, due to funding.

Many hospitals already offer nuchal scans, and the quad test. Adding the extra blood test at 15 weeks (to make the combined test into the integrated test), according to one screening insider, would cost the NHS "about £25". This isn't an official figure, but for about that, you could have a test that would substantially increase the detection rate and cut down false positives. We need to weigh this up against the cost of an amniocentesis, which has to be performed by an obstetrician further trained in fetal medicine. Oh, and against the potential loss of a healthy baby – but I guess that doesn't figure on anyone's spreadsheet.

Life and Style
ebookNow available in paperback
Latest stories from i100
Have you tried new the Independent Digital Edition apps?

ES Rentals

    Independent Dating

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    iJobs Job Widget
    iJobs General

    Guru Careers: Software Developer / C# Developer

    £40-50K: Guru Careers: We are seeking an experienced Software / C# Developer w...

    Guru Careers: Software Developer

    £35 - 40k + Benefits: Guru Careers: We are seeking a Software Developer (JavaS...

    SThree: Trainee Recruitment Consultant / Resourcer

    £18000 - £23000 per annum + Commission: SThree: As a Trainee Recruitment Consu...

    Ashdown Group: UI Developer - (UI, HTML, CSS, JavaScript, AngularJS)

    £25000 - £40000 per annum: Ashdown Group: UI Developer - (UI, JavaScript, HTML...

    Day In a Page

    Sun, sex and an anthropological study: One British academic's summer of hell in Magaluf

    Sun, sex and an anthropological study

    One academic’s summer of hell in Magaluf
    From Shakespeare to Rising Damp... to Vicious

    Frances de la Tour's 50-year triumph

    'Rising Damp' brought De la Tour such recognition that she could be forgiven if she'd never been able to move on. But at 70, she continues to flourish - and to beguile
    'That Whitsun, I was late getting away...'

    Ian McMillan on the Whitsun Weddings

    This weekend is Whitsun, and while the festival may no longer resonate, Larkin's best-loved poem, lives on - along with the train journey at the heart of it
    Kathryn Williams explores the works and influences of Sylvia Plath in a new light

    Songs from the bell jar

    Kathryn Williams explores the works and influences of Sylvia Plath
    How one man's day in high heels showed him that Cannes must change its 'no flats' policy

    One man's day in high heels

    ...showed him that Cannes must change its 'flats' policy
    Is a quiet crusade to reform executive pay bearing fruit?

    Is a quiet crusade to reform executive pay bearing fruit?

    Dominic Rossi of Fidelity says his pressure on business to control rewards is working. But why aren’t other fund managers helping?
    The King David Hotel gives precious work to Palestinians - unless peace talks are on

    King David Hotel: Palestinians not included

    The King David is special to Jerusalem. Nick Kochan checked in and discovered it has some special arrangements, too
    More people moving from Australia to New Zealand than in the other direction for first time in 24 years

    End of the Aussie brain drain

    More people moving from Australia to New Zealand than in the other direction for first time in 24 years
    Meditation is touted as a cure for mental instability but can it actually be bad for you?

    Can meditation be bad for you?

    Researching a mass murder, Dr Miguel Farias discovered that, far from bringing inner peace, meditation can leave devotees in pieces
    Eurovision 2015: Australians will be cheering on their first-ever entrant this Saturday

    Australia's first-ever Eurovision entrant

    Australia, a nation of kitsch-worshippers, has always loved the Eurovision Song Contest. Maggie Alderson says it'll fit in fine
    Letterman's final Late Show: Laughter, but no tears, as David takes his bow after 33 years

    Laughter, but no tears, as Letterman takes his bow after 33 years

    Veteran talkshow host steps down to plaudits from four presidents
    Ivor Novello Awards 2015: Hozier wins with anti-Catholic song 'Take Me To Church' as John Whittingdale leads praise for Black Sabbath

    Hozier's 'blasphemous' song takes Novello award

    Singer joins Ed Sheeran and Clean Bandit in celebration of the best in British and Irish music
    Tequila gold rush: The spirit has gone from a cheap shot to a multi-billion pound product

    Join the tequila gold rush

    The spirit has gone from a cheap shot to a multi-billion pound product
    12 best statement wallpapers

    12 best statement wallpapers

    Make an impact and transform a room with a conversation-starting pattern
    Paul Scholes column: Does David De Gea really want to leave Manchester United to fight it out for the No 1 spot at Real Madrid?

    Paul Scholes column

    Does David De Gea really want to leave Manchester United to fight it out for the No 1 spot at Real Madrid?