Are Ultrasounds safe?

Worried professionals

We know that Professor Stuart Campbell (the most vociferous ultrasound propagandist) attended the same Medical Research Council conference in 1985 as we did, where a number of experts made their anxieties clear. Yet, Professor Campbell persists in his claims of safety:

"Some 100 million people throughout the world are walking around having had scans before they were born, and there has never been a shred of evidence that it does any harm."1

No one then - or since - has thought to ask whether that statement was based on any research evidence. The press was (and still is) happy to accept without challenge a statement made by a medical man who, as one of the most enthusiastic promoters of ultrasound, can hardly be unbiased.

A number of private companies have been quick to set up these money-making services even though exposure to high intensity ultrasound has never been properly researched for any possible risks to either fetus or mother. This proved to be too much for some members of the medical profession. Martin Whittle, professor of fetal medicine and chair of the Royal College of Obstetricians and Gynaecologists' working party on ultrasound was quoted in The Sunday Times as saying:
"We don't know the effects of repeated ultrasound".

The US Food and Drug Administration (FDA) has declared that ultrasound is a form of energy that can't be considered harmless, even at low levels, and is considering regulatory action against the commercial companies that are offering ultrasound videos in the US.

Dr John Steed, head of obstetrics and gynaecology at the Virginia Commonwealth University School of Medicine said that, although there is no proof that ultrasound is damaging, "We used to think that about X-rays". (Indeed, X-rays were vigorously promoted for viewing the baby in the womb, and it was many years later that research showed that X-ray exposure in utero caused cancer in the children who were exposed as babies).

Nevertheless, there appear to be no such concerns in Professor Campbell's mind. Having created a company to offer these keepsake videos (at a cost of £200 a time), he was asked for his views: "A great deal of research has been done over the past 30 years to investigate if fetal ultrasound has any effect on the baby and there is no evidence whatsoever of harm."

However, as a professor of obstetrics and the leading protagonist for ultrasound, it is astonishing that he seems not to have considered the following studies.
Obstetricians in Michigan3 studied 57 women who were at risk of giving birth prematurely. Half were given a weekly ultrasound examination; the rest received pelvic examinations to assess the state of their cervix. Preterm labour was more than doubled in the ultrasound group - 52 per cent - compared with 25 per cent in the controls. Although this was a small-scale study, this statistical difference was unlikely to have emerged by chance.

In a large randomised controlled trial from Helsinki,4 9000 women were randomly divided into two groups. The women in one group were scanned at 16-20 weeks whereas the women in the other group were not. Comparing the results from these groups revealed 20 miscarriages in the scanned group and none in the controls.

A later study carried out in London5 randomised 2475 women to receive routine Doppler ultrasound examination of the umbilical and uterine arteries at 19-22 weeks and at 32 weeks of pregnancy compared with women who received standard care without Doppler ultrasound. There were 16 perinatal deaths of normally formed infants in the Doppler group compared with four in the standard-care group.

It is not only pregnant women receiving antenatal care who are at risk. Physiotherapists use ultrasound to treat a number of conditions. A study done in Helsinki6 found that, if the physiotherapist was pregnant, handling ultrasound equipment for at least 20 hours a week significantly increased the risk of a spontaneous abortion.

Also, the risk of spontaneous abortions in practitioners after the tenth week of pregnancy was significantly increased when they gave deep-heat treatments (for strain injuries or as mobilization therapy) for more than five hours a week, and ultrasound for more than 10 hours a week.
One can only wonder what exactly is Professor Campbell's definition of harm?

Mouse study shows ultrasound affecting brain development

by Nicole Yannoulatos

SYDNEY, 9 August 2006 - The impact of ultrasounds on embryonic brains may be more damaging that was previously thought, according to U.S. researchers.
A study conducted by Pasko Rakic and colleagues at Yale University in New Haven, Conneticutt, has found that a significant number of nerve cells in the brain of embryonic mice do not migrate to the appropriate location following exposure to ultrasound.

"Proper migration of neurons during development is essential for normal development of the brain's cerebral cortex, and its function can be impaired if neuronal migration is disrupted," said Rakic, chairman of the Department of Neurobiology at the university.

His team analysed how effectively neurons in the brains of one 146 mouse embryos migrated to the brain's cerebral cortex once exposed to ultrasound waves.
They found that after several prolonged exposures, a small number of neurons did not migrate to their necessary position in the upper layers of the cerebral cortex, and instead moved to the lower layers or became embedded in supporting white matter in the brain.

In an accompanying commentary, Verne Caviness of Boston's Massachusetts General Hospital and Ellen Grant of Harvard Medical School, explain how the implications of this research for the developing brain is unknown.

They argued that since the number of misplaced cells is so small, their effect may be little more than minimal background noise. The cells also appear to retain their intended cell characteristics, despite migrating to the wrong position.

Caviness and Grant describe how after the neurons have migrated, a large proportion of them are naturally eliminated as cells die from the development of new tissues in the brain as the embryo grows. Essentially, all of the misplaced cells in the mouse's brain may be eliminated and will be of no consequence for the organisation of the cortex.

This study does not necessarily suggest that ultrasound will have the same affect on human foetuses. Rakic and his colleagues said there were clear differences between their research and the average pre-natal ultrasound women would undergo during pregnancy.

The brains of the embryonic mice were exposed with a larger volume of ultrasound waves and more frequently than a human foetus would be, they said. The authors also highlighted the differences in the biology of mice and humans, making it difficult to predict what affect the ultrasounds may have on humans.

"It is not known whether or to what extent ultrasound waves affect migrating neurons in developing humans," said Rakic.
He highlighted the difficulties in identifying the position of neurons, since it requires researchers to label the DNA replication, a procedure that cannot be used in humans. This means that the misplaced cells in the embryonic brain could be missed totally when tests are taking place.

However, they said the study serves as a reminder that we can't always take routine medical procedures for granted. While the research does not suggest ultrasounds are anything to be concerned about, it does highlight an area of embryonic development that calls for more study.
Rakic and his colleagues intend to extend the study to non-human primates to see if similar effects occur.

Links to similar articles:
Excessive Ultrasound May Harm Embryonic Neurons
Ultrasound Scans May Harm Unborn Babies
Ultrasound scans 'safe for baby'
What is Ultrasound?
Who says ultrasound is safe?