Re: ULTRASOUND digest 1453
From: joshua copel (joshua.copel@yale.edu)
Wed Dec 19 13:04:22 2001
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Lousy article. A few of many reasons:
1. Determination of handedness was based on how recruits to Swedish army shouldered a rifle. Not a particularly good way to
determine handedness. For example here in the US we have many baseball players who bat with one hand but throw with the other.
Are they right or left handed? Did all lefties shoulder the rifle to the left? Sarcastic remark: who says left-handedness brain damage anyways?
2. Assignment of whether US was performed was based solely on birth year and location, i.e. where and when you were born was
assumed to correlate accurately with whether or not you were exposed to US.
3. Effects only appeared in 1 of 2 sets of birth years studied, and only at 1 hospital (Malmo)
4. US in 70's was not same as today in terms of time taken for scanning or acoustic output.
5. Association, even if it were really present, is NOT the same as causality. How many times do we have to learn that lesson in
medicine?
ISUOG Safety Committee will have a statement on our website soon. There has been lots of attention to this article apparently
in Europe, UK & Australia. Fortunately little or none here in US. If anyone wants to read full study it is in November
Epidemiology, though as far as I can find that is not available as an ejournal, unfortunately.
Josh Copel
>
> Date: Wed, 19 Dec 2001 16:23:17 -0200
> From: "Ricardo Savaris" <savaris@orion.ufrgs.br>
> To: <ultrasound@obgyn.net>
> Subject: Fw: Ultrasound Linked to Brain Damage
>
> Ultrasound Scans Linked to Brain Damage in Babies 12/19/01Just received > today,
>
> Any comments?
>
> Ricardo Savaris, MD
>
> Ultrasound Scans Linked to Brain Damage in Babies
> By Robert Matthews
>
> Evidence suggesting that ultrasound scans on pregnant women cause > brain damage in their unborn babies has been uncovered by scientists.
>
> In the most comprehensive study yet on the effect of the scanning, > doctors have found that men born to mothers who underwent scanning were > more likely to show signs of subtle brain damage.
>
> During the 1990s, a number of studies hinted that ultrasound > scanning affected unborn babies. Research has suggested that subtle > brain damage can cause people who ought genetically to be right-handed > to become left-handed. In addition, these people face a higher risk of > conditions ranging from learning difficulties to epilepsy.
>
> Now a team of Swedish scientists has confirmed the earlier reports > on the effects of ultrasound with the most compelling evidence yet that > unborn babies are affected by the scanning. They compared almost 7,000 > men whose mothers underwent scanning in the 1970s with 170,000 men whose > mothers did not, looking for differences in the rates of left- and > right-handedness.
>
> The team found that men whose mothers had scans were significantly > more likely to be left-handed than normal, pointing to a higher rate of > brain damage while in the womb. Crucially, the biggest difference was > found among those born after 1975, when doctors introduced a second scan > later in pregnancy. Such men were 32 per cent more likely to be > left-handed than those in the control group.
>
> Reporting their findings in the journal Epidemiology, the > researchers warned that scans in late pregnancy were now routine in many > countries.
>
> The present results suggest a 30 per cent increase in risk of > left-handedness among boys pre-natally exposed to ultrasound. If this > association reflects brain injury, this means as many as one in 50 male > fetuses pre-natally exposed to ultrasound are affected.
>
> Other doctors and scientists caution that until further studies > are carried out, scanning should still be regarded as safe by > mothers-to-be. If confirmed, however, the findings would mean that > ultrasound scans are causing slight brain damage in thousands of babies > in Britain each year.
>
> Ultrasound scans, which were introduced in the 1960s, have long > been regarded as a safe means of checking on the health of unborn > children. The scanners use high-frequency sound waves to give X-ray-like > images of the inside of the womb, but without using radiation, which > carries a risk of causing cancer. Between the 1960s and today, the > number of pregnant women having scans in western Europe has increased > from a handful to virtually all of them.
>
> Normally, left-handedness is genetic: the likelihood of two > left-handed parents having a left-handed child is 35 per cent, while for > two right-handed parents, it is only nine per cent. It is when the > incidence of left-handedness begins to rise above these normal rates > that scientists become concerned that brain damage of some kind could be > a factor.
>
> Other surveys have shown that premature babies are five times more > likely than normal to be left-handed. According to the Swedish > researchers, the human brain undergoes critical development until > relatively late in pregnancy, making it vulnerable to damage. In > addition, the male brain is especially at risk, as it continues to > develop later than the female brain.
>
> The growing evidence that ultrasound affects unborn babies may > cast new light on the puzzling rise in left-handedness over recent > years.
>
> In Britain, the rate has more than doubled, from five per cent in > the 1920s to 11 per cent today. Researchers have estimated that only 20 > per cent of this rise can be put down to the suppression of > left-handedness among the older generation.
>
> Dr Francis Duck of the British Medical Ultrasound Society will > chair a discussion of the results at the international meeting of > ultrasound experts being held this week in Edinburgh. "When the first > study suggesting a link came out, it was possible to ignore it, but now > this is the third," he said. "What it demonstrates is the need to > investigate the link further, and to look at possible mechanisms."
>
> Dr Duck cautioned, however, that ultrasound scanning has saved the > lives of countless babies: "This research must be seen in context, and > it should not deter anyone from having an antenatal scan."
>
> Beverley Beech, the chairman of the Association for Improvements > in Maternity Services, criticized doctors for insisting for years that > ultrasound was totally safe.
>
> "I am not sure at all that the benefits of ultrasound scans > outweigh the downsides," said Ms Beech. "We should be advising women to > think very, very carefully before they have scans at all."
>
> http://www.news.telegraph.co.uk December 9, 2001
>
> Epidemiology December 2001 12:618
>
> -------------------------------------------------------------------------> -
> ------------------------------------------------------------------------->
> -------------------------------------------------------------------------> DR. MERCOLA'S COMMENT:
>
> This is certainly not new information, as I reported on this over > two years ago, but the evidence seems quite compelling now to avoid > ultrasounds during pregnancy unless they are absolutely necessary.
>
> Currently in the UK, women typically have one or two ultrasonic > scans during pregnancy, although more can be recommended to track a > particular condition in the fetus.
>
> I never did OB in my practice, but I suspect that the > recommendation is similar in the U.S.
>
> It sure seems that the time for routine ultrasound examinations > has come and gone.
>
> How ultrasound could affect the brain is still a mystery though. > Some researchers suspect that a process called cavitation - where small > bubbles in the body fluids vibrate in the ultrasonic waves - could > influence brain development.
>
> In the early stage of pregnancy, neurons migrate from the center > of the brain and this could be disturbed by ultrasound, perhaps through > cavitation.
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