Tuesday, April 26, 2011

Ultrasound Scans- Cause for Concern

@ Dr Sarah J. Buckley MD 2005 www.sarahbuckley.com
Previously versions have been published in
Mothering magazine, issue 102, Sept-Oct 2000, and Nexus magazine, vol 9, no 6, Oct-Nov 2002.
A fully updated and expanded version is published in
Gentle Birth, Gentle Mothering: A Doctor’s Guide to Natural Childbirth and Gentle Early Parenting Choices (Sarah J Buckley MD, Celestial Arts, 2009).


When I was pregnant with my first baby in 1990, I decided against having a scan. This was a rather unusual decision, as my partner and I are both doctors and had even done pregnancy scans ourselves- rather ineptly, but sometimes usefully- while training in GP/family physician obstetrics a few years earlier.
What influenced me the most was my feeling that I would lose something important as a mother if I allowed someone to test my baby. I knew that if a minor or uncertain problem showed up – and this is not uncommon — that I would be obliged to return again and again, and that after a while, it would feel as if my baby belonged to the system, and not to me.
In the years since then I have had three more unscanned babies, and have read many articles and research papers about ultrasound. Nothing I have read has made me reconsider my decision. Although ultrasound may sometimes be useful when specific problems are suspected, my conclusion is that it is at best ineffective and at worse dangerous when used as a “screening tool” for every pregnant woman and her baby.
 
Ultrasound Past and Present

Ultrasound was developed during WWII to detect enemy submarines, and was subsequently used in the steel industry. In July 1955 Glasgow surgeon Ian Donald borrowed an industrial machine and, using beefsteaks as controls, began to experiment with abdominal tumours that he had removed from his patients. He discovered that different tissues gave different patterns of ultrasound “echo”, leading him to realise that ultrasound offered a revolutionary way to look into the previously mysterious world of the growing baby.1
This new technology spread rapidly into clinical obstetrics. Commercial machines became available in 19632 and by the late 1970’s ultrasound had become a routine part of obstetric care.3 Today, ultrasound is seen as safe and effective and scanning has become a rite of passage for pregnant women in developed countries. Here in Australia, it is estimated that 99 percent of babies are scanned at least once in pregnancy – mostly as a routine prenatal ultrasound (RPU) at 4 to 5 months. In the US, where this cost is borne by the insurer or privately, around 70 percent of pregnant women have a scan.4
However, there is growing concern as to its safety and usefulness. UK consumer activist Beverley Beech has called RPU “the biggest uncontrolled experiment in history”,5 and the Cochrane Collaborative Database – the peak scientific authority in medicine-concludes that,
…no clear benefit in terms of a substantive outcome measure like perinatal mortality [number of babies dying around the time of birth] can yet be discerned to result from the routine use of ultrasound.6
This seems a very poor reward for the huge costs involved. In 1997-8, for example, $39 million was paid by the Australian federal government for pregnancy scans- an enormous expense compared to $54 million for all other obstetric medicare costs.7 This figure does not include the additional costs paid by the woman herself. In the US, an estimated US$1.2 billion would be spent yearly if every pregnant woman had a single routine scan.
In 1987, UK radiologist H.D.Meire, who had been performing pregnancy scans for 20 years, commented,
The casual observer might be forgiven for wondering why the medical profession is now involved in the wholesale examination of pregnant patients with machines emanating vastly different powers of energy which is not proven to be harmless to obtain information which is not proven to be of any clinical value by operators who are not certified as competent to perform the operations.8
The situation today is unchanged, on every count.
The 1999 Senate Committee report, ‘Rocking the Cradle’ recommended that the cost-benefit of routine scanning, and of current ultrasound practices, be formally assessed. Recommendations were also made to develop guidelines for the safe use of all obstetric ultrasound, as well as for the development of standards for the training of ultrasonographers (see below). So far, none of these recommendations have been implemented.7
  
Biological Effects of Ultrasound

Ultrasound waves are known to affect tissues in two main ways. Firstly, the sonar beam causes heating of the highlighted area by about one degree celsius. This is presumed to be non-significant, based on whole-body heating in pregnancy, which seems to be safe up to 2.5 degrees Celsius.19
The second recognised effect is cavitation, where the small pockets of gas which exist within mammalian tissue vibrate and then collapse. In this situation
…temperatures of many thousands of degrees celsius in the gas create a wide range of chemical products, some of which are potentially toxic. These violent processes may be produced by micro-second pulses of the kind which are used in medical diagnosis….19
The significance of cavitation effects in human tissue is unknown.
A number of studies have suggested that these effects are of real concern in living tissues. The first study suggesting problems was a study on cells grown in the lab. Cell abnormalities caused by exposure to ultrasound were seen to persist for several generations.20 Another study showed that, in newborn rats, (who are at a similar stage of brain development to humans at four to five months in utero), ultrasound can damage the myelin that covers nerves,21 indicating that the nervous system may be particularly susceptible to damage from this technology.
Brennan and colleagues, reported that exposing mice to dosages typical of obstetric ultrasound caused a 22 percent reduction in the rate of cell division, and a doubling of the rate of aptosis, or programmed cell death, in the cells of the small intestine.22

Mole comments

If exposure to ultrasound… causes death of cells, then the practice of ultrasonic imaging at 16 to 18 weeks will cause loss of neurones [brain cells] with little prospect of replacement of lost cells…The vulnerability is not for malformation but for maldevelopment leading to mental impairment caused by overall reduction in the number of functionning neurones in the future cerebral hemispheres.23
Studies on humans exposed to ultrasound have shown that possible adverse effects include premature ovulation,24 preterm labour or miscarriage,15 25 low birth weight,26 27 poorer condition at birth,28 29 perinatal death,28-30 dyslexia,31 delayed speech development,3233-36 Non right-handedness is, in other circumstances, seen as a marker of damage to the developing brain.35 37 One Australian study showed that babies exposed to 5 or more doppler ultrasounds were 30% more likely to develop intrauterine growth retardation (IUGR)- a condition that ultrasound is often used to detect.26 and less right-handedness.
Two long-term randomised controlled trials, comparing exposed and unexposed childrens’ development at eight ti nine years old, found no measurable effect from ultrasound.38 3940 However, as the authors note, intensities used today are many times higher than in 1979 to 1981. Further, in the major branch of one trial, scanning time was only three minutes. More studies are obviously needed in this area, particularly in the areas of Doppler and vaginal ultrasound, where exposure levels are much higher.
A further problem with studying ultrasound’s effect is the huge range of output, or dose, possible from a single machine. Modern machines can give comparable ultrasound pictures using a lower, or a 5 000 times higher dose,8 and there are no standards to ensure that the lowest dose is used. Because of the complexity of machines, it is difficult to even quantify the dose given in each examination.41 In Australia training is voluntary, even for obstetricians, and the skill and experience of operators varies widely.
A summary of the safety of ultrasound in human studies, published in May 2002 in the prestigious US journal Epidemiology concluded
…there may be a relation between prenatal ultrasound exposure and adverse outcome. Some of the reported effects include growth restriction, delayed speech, dyslexia, and non-right-handedness associated with ultrasound exposure. Continued research is needed to evaluate the potential adverse effects of ultrasound exposure during pregnancy. These studies should measure the acoustic output, exposure time, number of exposures per subject, and the timing during the pregnancy when exposure(s) occurred.42

Conclusions and Recommendations

I would urge all pregnant women to think deeply before they choose to have a routine ultrasound. It is not compulsory, despite what some doctors have said, and the risks, benefits and implications of scanning need to be considered for each mother and baby, according to their specific situation.
If you choose to have a scan, be clear about the information that you do and do not want to be told. Have your scan done by an operator with a high level of skill and experience (usually this means performing at least 750 scans per year) and say that you want the shortest scan possible. Ask them to fill out the form, or give you the information, as above, and to sign it.
If an abnormality is found, ask for counselling and a second opinion as soon as practical. And remember that it’s your baby, your body and your choice.

For Full Article and Resources go to...
http://www.sarahbuckley.com/ultrasound-scans-cause-for-concern/

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