Weighing the risks; what you should know about ultrasound!

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http://www.mothering.com/articles/pregnancy_birth/birth_preparation/ultrasound-risks.html

By Sarah Buckley
Issue 102, September/October 2000

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While many women are reassured by a normal scan, in fact RPU detects only between 17 percent and 85 percent of the one in 50 babies that have major abnormalities at birth. 5,6 A recent study from Brisbane, Australia, showed that ultrasound at a major women's hospital missed about 40 percent of abnormalities, many of which are difficult or impossible to detect.7 The major causes of intellectual disability, such as cerebral palsy and Down syndrome, or heart and kidney abnormalities, are unlikely to be picked up on a routine scan.

There is also a small chance that the diagnosis of an abnormality is false positive. In some instances, normal babies have been aborted because of false-positive diagnoses.8 A United Kingdom survey found that one in 200 babies aborted for major abnormalities were wrongly diagnosed.9

In addition to false positives, there are also uncertain cases in which the ultrasound image cannot be easily interpreted, and the outcome for the baby is not known. In one study involving babies at higher risk of abnormalities, almost 10 percent of scans were uncertain.10 This can create immense anxiety for the woman and her family that may not be allayed by the birth of a normal baby: in the same study, mothers with questionable diagnoses still had associated anxiety three months after the child's birth. Uncertain findings also lead to repeated and/or prolonged scans, increasing the expense, inconvenience, and dosage of ultrasound.

In some cases of uncertainty, further tests such as amniocentesis are recommended. In such situations, there may be up to two weeks wait for results, during which time a mother must consider whether or not she will terminate the pregnancy if an abnormality is found. Even mothers who receive reassuring news have felt that this process has interfered with their relationship with their babies.11

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From a research perspective, the most significant benefit of RPU is a small reduction in perinatal mortality, that is the number of babies dying around the time of birth. This is, however, merely a statistical reduction since perinatal mortality rates do not include deaths that occur before five to six months' gestation. Often when a baby is found to have a fatal abnormality on RPU, the pregnancy is terminated before this time, excluding the baby from perinatal statistics.

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Reasons for Concern
Ultrasound waves are known to affect living tissues in at least two ways. First, the sonar beam heats the highlighted area by about 1Â°C (2Â°F). This is presumed to be insignificant, based on whole-body heating in pregnancy, which seems to be safe up to 2.5Â°C (5Â°F).21 The second effect is cavitation, where the small pockets of gas that 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."22 The significance of cavitation in human tissue is unknown.

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A number of studies have suggested that these effects are of real concern in living tissues. The first study indicating problems analyzed cells grown in the lab. Cell abnormalities caused by exposure to ultrasound were seen to persist for several generations.23 Another study showed that, in newborn rats (who are at a similar stage of brain development as humans at four to five months in utero), ultrasound can damage the myelin that covers nerves,24 indicating that the nervous system may be particularly susceptible to damage from this technology. In 1999, an animal study by Brennan and colleagues, reported in New Scientist,25 showed 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 cell death in the cells of the small intestine.

Studies on humans exposed to ultrasound have shown possible adverse effects, including premature ovulation,26 preterm labor or miscarriage,27, 28 low birthweight,29 poorer condition at birth,30, 31 dyslexia,32 delayed speech development,33 and less right-handedness,34, 35 a factor which in some circumstances can be a marker of damage to the developing brain. In addition, one Australian study showed that babies exposed to five or more ultrasounds were 30 percent more likely to develop intrauterine growth retardation (IUGR)--a condition that ultrasound is often used to detect.36

Two long-term randomized controlled trials, comparing exposed and unexposed children's development at eight to nine years of age, found no measurable effect from ultrasound.37, 38 However, as the authors note, intensities used today are many times higher than in 1979 to 1981. A later report of one of these trials39 indicated that scanning time was only three minutes. More studies are obviously needed in this area, particularly in Doppler ultrasound, where exposure levels are much higher, and in vaginal ultrasound, where there is less tissue shielding the baby from the transducer.

I remember reading a book I think "Medical Madness" which indicated that this ultrasound was the cause of all the ADD type issues with children. I think ADD is also linked to poor nutrition/ high sugar/chemical breakfasts.