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NHS study questions date scans

NHS research has challenged the need for GPs to send women for a dating scan in the early stages of pregnancy.

By Emma Wilkinson

Nice recommends GPs offer all women a first-trimester scan because of their effectiveness at reducing inductions ­ but the researchers found no evidence of benefit. Their study, the first in the UK to assess the effectiveness of dating scans, concluded they were 'a more expensive health care strategy'.

Study leader Dr Debbie Harrington, sub-specialist registrar in maternal and fetal medicine at John Radcliffe Hospital in Oxford, said: 'In our population we didn't find a scan reduced the need for induction. It was just an additional cost and we didn't see the advantage.'

The study, published in the International Journal of Obstetrics and Gynaecology (February), recorded 13 changes to estimated delivery dates among women who received dating scans, and two in a comparison group, whose gestational stage was calculated from the last menstrual period. ut this had no effect on the rate of inductions, which was 8.2 per cent in scanned and 7.4 per cent in unscanned women .

Professor James Walker, professor of obstetrics and gynaecology at St James's University Hospital in Leeds, said: 'Most estimates show that up to 15 per cent of women are inaccurate in estimating their last period, because they can't remember or their cycle is irregular ­ but in this study it was only 5 per cent.

'It probably depends on the client group. Certainly they showed it's of no value in Oxford, but it may be in inner London or other big cities.'

Dr Harrington agreed: 'It is reasonable to expect population characteristics would alter the effect of dating scans. In our population the women were accurate historians. Health authorities need to work out if it is cost-effective for them.' n early scan was one way of testing for Down's, she added.

The research, funded by the NHS Executive, studied 463 women attending their GP in the first trimester to confirm pregnancy with no indication for an ultrasound scan.

Are dating scans worth it?

SHAs may decide to phase out dating scans if:

  • Local women are accurate at estimating last menstrual period
  • Induction rates are low
  • Women have an anomaly scan at 20 weeks anyway
  • Scans are not used to screen for Down's syndrome

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