Читать книгу What Doctors Don’t Tell You - Lynne McTaggart, Lynne McTaggart - Страница 27

The mainstay of modern obstetric diagnosis is the ultrasound scan (or sonography) and is the most likely test you’ll be given, following hard at the heels of your urine test confirming pregnancy in the first place. Most women these days can show off pictures of their babies in the womb when they are not much past the tadpole stage. First developed during the Second World War to track down enemy submarines, ultrasound scanning began to be used in the 1970s for diagnostic testing and eventually for pregnancy.

Similar to radar, real-time scanners employ very-high-frequency pulsed sound waves (3.5–7 mHz, or 3.5–7 million cycles per second) that are sent to the foetus via a transducer placed on the abdomen. Echoes of the sound waves create moving images on the monitor screen.

In the radiology industries ultrasound is known as the biggest growth area, with equipment manufacturers enjoying a 20 per cent growth in sales over the next few years and some 60 to 90 million investigative tests of all sorts performed every year.¹ Although originally planned to be used for aiding high-risk pregnancies, the exam is now presently looked upon, as New York’s Columbia University Professor Harold E. Fox once put it, as the equivalent of a ‘physical exam of the foetus in utero’,² with a good reading the tacit assurance of a healthy baby. Virtually all pregnant women are now scanned and given photos or videos to take home as a pleasantly packaged souvenir of their first baby picture.

It’s meant to determine whether your baby is healthy and when you are likely to give birth. Scans supposedly can assess gestational age, size and growth, rule out multiple or tubal pregnancies or ovarian cysts, locate the position of the baby in the womb, and show whether the baby is growing properly or whether it has died.

A scan before 20 weeks also looks for abnormalities such as hydrocephalus, anencephaly, spina bifida, cleft lip or palate and congenital heart problems. Ultrasound is increasingly being used to pick up so-called ‘soft markers’ – subtle defects which may or may not be serious. It can identify club foot, low-set ears and even problems with facial development.

It is now the first port of call for checking for chromosomal abnormalities such as Down’s syndrome. At the bare minimum, women are scanned at 12, 18–20 and 34 weeks of pregnancy. Many are scanned 10 or 12 times before giving birth, starting as early as seven weeks into the pregnancy. In late pregnancy it is used to rule out placenta praevia, when a low-lying placenta blocks the birth passage.

Although doctors rely on scanning as an early warning signal of problems that can largely be remedied, babies who are scanned tend to have poorer outcomes, possibly because scans simply invite more invasive procedures that don’t appear to aid survival. In one study, more of the scanned babies died, were delivered sooner and spent more time in hospital and on ventilators than babies who were not scanned. Of those with abdominal wall defects, the scanned group were operated on sooner, but had the same outcomes as unscanned babies whose operations were delayed. Furthermore, more of the scanned babies died (23 per cent vs only 4 per cent of the unscanned babies).³ A German study found that caesarean section and preterm delivery was five times more frequent, and admission into intensive care three times higher, for babies diagnosed by ultrasound before birth.⁴

In the UK and the US, pregnant women are generally told by their doctors that ultrasound is as safe as a television set. The official line of the Royal College of Obstetricians and Gynaecologists is that the wave intensity currently used in scans is ‘probably’ safe. Obstetricians take the airy position that there are 50 million people walking around today who were scanned in the womb, and with no laboratory evidence to indicate that it is a hazard, they must be all right.⁵ And it is true that the very short pulses of sound that produce echoes and ultimately the pictures you see on the screen when they hit soft tissue – 1,000 pulses to a second, each lasting one-millionth of a second – have never been definitely shown to cause heating or bubbles in the tissues of human babies.⁶

Nevertheless, this position ignores a growing body of medical evidence to the contrary, so much so that all of the pertinent US regulatory bodies urge obstetricians not to use ultrasound routinely.

The enthusiastic and uncritical embracing of this new technology reminds many of what happened in the US with diethylstilbestrol (DES), the wonder drug of the fifties that was supposed to cure miscarriage. The side-effects of the drug are only now showing up in adult offspring some 30 years later, in the form of reproductive problems and cancer.

The fact is, any woman who has had a foetal ultrasound scan is participating in one of the biggest laboratory experiments in medical history. Both in the US and the UK, the regulatory bodies approved the use of ultrasound without any long-term studies being done, leading the public to assume that the procedures are safe.

‘No well controlled study has yet proved that routine scanning of prenatal patients will improve the outcome of pregnancy.’ That was the official statement put forward by the American College of Obstetrics and Gynecology (ACOG) in 1984.⁷ At a 1988 meeting in London jointly held by the Royal Society of Medicine and the ACOG, several top obstetricians, as well as the executive director of the ACOG, disclosed that of eight major studies attempting to evaluate the effectiveness of ultrasound, ‘none has shown [that] routine use improves either maternal or infant outcome over that achieved when diagnostic ultrasound was used only when medically indicated.’⁸

As studies into the effects of ultrasound began to be done in the late eighties and nineties, they confirmed these early suspicions. Two researchers in Switzerland did an analysis of all the scientific (that is, randomized, controlled) studies of ultrasound scanning to evaluate its effect on the outcome of pregnancy. Their conclusion: ultrasound doesn’t make one bit of difference to the ultimate health of the baby. This means it doesn’t improve the live birth rate or help to produce fewer problem babies.⁹ One reason it makes no difference in terms of live births is that the babies who are usually aborted after a scan shows up a severe malformation are usually those who would have died during pregnancy or shortly after birth, anyway.

The only good reason to use ultrasound, the researchers concluded, is to screen for gross congenital malformations – not to ensure your baby is ‘all right’, the usual vague rationale offered to most pregnant woman with no suspicious symptoms.

Another study of 15,000 American women also found ‘no significant differences in the rate of adverse perinatal outcome (foetal or neonatal death or substantial neonatal morbidity)’ between those scanned and those in the control group. The number of premature babies were identical in the two groups, as were the outcomes of multiple births, late-term pregnancies and small-for-dates babies.¹⁰ As Dr Richard Berkowitz of New York’s Mount Sinai Medical Center concluded: ‘None of the studies published to date demonstrates an effect on the outcome of pregnancy in most low-risk women.’¹¹

In fact, some studies show that, with ultrasound, you are more likely to lose your baby. A study from Queen Charlotte’s and Chelsea Hospital in London found that women having doppler ultrasound were more likely to lose their babies than those who received only standard neonatal care (17 deaths to 7).¹² It can increase the risk of miscarriage,¹³ even among women exposed to occupational sonography for more than 10 hours a week.¹⁴

It has been shown to trigger premature birth, doubling the rate in at-risk women given weekly scans.¹⁵ The evidence is fairly conclusive that ultrasound doesn’t do any good in normal pregnancies. But does subjecting an embryo to ultrasound at a delicate stage of development do any lasting harm? New studies have emerged showing that ultrasound scanning may indeed cause subtle brain damage. According to a Norwegian study of 2,000 babies, performed by the National Centre for Foetal Medicine in Trondheim, those subjected to routine ultrasound scanning were 30 per cent more likely to be left-handed than those who weren’t scanned.¹⁶ This predilection for left-handedness appears to show up only in boys. In a later analysis of 177,000 Swedish men, those whose mothers had scans were 32 per cent more likely to be left-handed.¹⁷ In Britain, the rate of left-handedness has more than doubled – from 5 per cent in the 1920s to 11 per cent today. Neurologists believe that slight brain damage can cause right-handed people to become left-handed.

Evidence from Australia demonstrates that frequent scans also appear to restrict growth.¹⁸ Exposure to ultrasound also causes delayed speech, according to Canadian research. Professor James Campbell, an ear, nose and throat surgeon in Alberta, Canada, compared a group of 72 children who had speech problems with a similar group with no such difficulties. He found that most of those with delayed speech had been exposed to ultrasound in the womb, whereas most of those with normal speech had not. ‘The possibility of subtle microscopic changes in developing neural tissue exposed to ultrasound waves has to be considered,’ he concluded.¹⁹

These findings are particularly alarming given that the women in the study had only one scan apiece. Most pregnancies in Britain and North America involve at least two scans, and others many more, whether or not there is even a whiff of a problem.

Animals have exhibited delayed neuromuscular development, altered emotional behaviour and lowered birthweight with exposure at the equivalent of current diagnostic levels.²⁰ Rodents exposed to high-intensity ultrasound have also had low birthweights and nerve damage.²¹

Children who’d been exposed to ultrasound in the womb had a higher incidence of dyslexia, according to one study.²² Mothers whose babies were scanned show a 90 per cent increase in foetal activity,²³ the effect of which on their future development is anyone’s guess. Ultrasound also exposes the foetus to a loud noise of 100 decibels, similar to the highest notes on a piano – as loud as an underground train arriving at a station.²⁴

Work performed in the laboratory may provide some clues as to how scanning could cause damage. We know that sonography produces biological effects in two ways: heat and cavitation (the production of bubbles which expand and contract with the sound waves). We also know that ultrasound causes shock waves in liquid, but we don’t know if it does so in human tissue – or for that matter, amniotic fluid. Finally, we don’t know whether the effects are cumulative – that is, if they increase with multiple exposure or duration. This is an important issue now that doctors routinely order multiple scans. It also may have a bearing on electronic foetal monitoring, which employs ultrasound (although at one-thousandth of a scan’s peak intensity) to monitor the baby’s heartbeat during labour and delivery, often by being aimed at one spot for 24 hours.

An analysis of in vitro studies shows that ultrasound has produced cell damage and changes in DNA. The most widely quoted studies are those of radiologist Doreen Liebeskind at New York’s Albert Einstein College of Medicine. After exposing cells in suspension to low-intensity pulsed ultrasound for 30 seconds, she observed changes in cell appearances and motility, DNA, abnormal cell growth and chromosomes, some of which were passed on to succeeding cell generations. In a documentary made of Dr Liebeskind’s results, the film showed normal cells with rounded edges more or less moving in tandem. After exposure to ultrasound, the cells became ‘frenetic and distorted’, and entangled with one another, wrote Doris Haire, president of the American Foundation of Maternal and Child Health, one of America’s best-briefed and most vociferous critics of routine ultrasound use.²⁵ Robert Bases, chief of Radiology at Albert Einstein College, reviewing what he termed the ‘bewildering array of ultrasound bioeffects described in over 700 publications since 1950’, said Dr Liebeskind’s results had been confirmed by four independent laboratories.²⁶

Dr Liebeskind herself theorizes that these cell changes may affect the developing brain. ‘There may be some subtle or delayed effect on neuron interconnection or some type of effect that is not readily apparent until later,’ she says.²⁷ Dr Liebeskind and others believe the in vitro studies can help to pinpoint the subtle effects on humans that epidemiologists should be looking for. ‘I’d look for possible behavioural changes – in reflexes, IQ, attention span,’ she wrote.²⁸

The International Childbirth Education Association (ICEA) has maintained that ultrasound is most likely to affect development (behavioural and neurological), blood cells, the immune system and a child’s genetic make-up – a view that has been borne out by the recent evidence about weight and development in exposed children.²⁹ Ultrasound has also been shown to affect many parts of the mother’s body. A British study demonstrated that ovarian ultrasound can trigger premature ovulation in the mother.³⁰ There also have been published reports showing ultrasound’s potential to damage maternal erythrocytes (mature red blood cells) and raise chorionic gonadotropin levels (the hormone which helps to maintain the pregnancy).³¹ Again, we’re not really sure what this means, and whether a woman is more likely to miscarry after ultrasound exposure.

Despite the assurances of the UK’s Royal College of Obstetricians and Gynaecologists, every major American government agency has insisted that ultrasound not be used routinely on pregnant women. The FDA, the American Medical Association, the US National Institute of Child Health and Human Development, a top epidemiologist for the Centers for Disease Control and Prevention, the ACOG and the Bureau of Radiological Health have all cautioned doctors to use ultrasound only when indicated (say, to investigate unexplained vaginal bleeding) – a caution that has got thrown to the winds. They also specify that there is still no research proving this diagnostic test is safe. The Bureau of Radiological Health, for instance, has stated:‘Although the body of current evidence does not indicate that diagnostic ultrasound represents an acute risk to human health, it is insufficient to justify an unqualified acceptance of safety.’³²

Besides the safety issue, there are considerable questions about accuracy. There is a significant chance that your scan will indicate a problem when there isn’t one, or fail to pick up a problem actually there. One study found a ‘high rate’ of false-positives; 17 per cent of the pregnant women scanned were shown to have small-for-dates babies, when only 6 per cent actually did – an error rate of nearly one out of three.³³ Another study from Harvard showed that among 3,100 scans, 18 babies were erroneously labelled abnormal, and 17 foetuses with problems were missed.³⁴

Yet a third Swiss study pooling the results of all ultrasound studies concluded that 2.4 per 1,000 women will be given a false diagnosis of a malformed foetus. This high error rate has chilling repercussions for families who decide to opt for late-term abortions after a scan shows that their child has spina bifida.³⁵ In fact, the Swiss researchers concluded that the negligible benefits of ultrasound scanning (which don’t improve the outcome of pregnancy) aren’t worth exposing pregnant women to the ‘risk of false diagnosis’ of malformations.

In one of the largest studies on ultrasound to date (33,000 babies), ultrasound picked up only about half of the 725 babies with birth defects. Some 175 foetuses were given a false-positive result – labelled abnormal when they were healthy.³⁶ A Swedish study found that ultrasound picked up only a third of babies born with serious defects³⁷ and, in another study, only a third of growth-retarded babies were correctedly diagnosed before birth. Some 2 per cent were wrongly identified as such, even though their mothers had had nearly five scans apiece.³⁸

False-positives have increased 12-fold as ultrasound is increasingly used in an attempt to pick up subtle defects or conditions in late pregnancy.³⁹ This technology even wildly overdiagnoses placenta praevia (potentially fatal low-lying placenta in late pregnancy), one of its main indications; in one study, 250 women were identified as having the condition when it was only actually present in four.⁴⁰

At one point, the British press was filled with stories of women who may have aborted healthy babies due to inaccurate scans. In one, Jacqui James of Brierley Hill in the West Midlands, a 24-year-old mother of two, was told scans done at Birmingham Maternity Hospital during her 27th week of pregnancy showed that her third baby was not growing properly and likely to have brain damage. After a family discussion, she decided she had no choice but to have an abortion. Because she was more than six months pregnant, the ‘abortion’ was done by caesarean section. However, the baby girl, which survived the operation for 45 minutes, was later found to be perfectly healthy.⁴¹