Can frequent ultrasound diagnostics be harmful?

Are there any short or long term effects apparent in tissues if a zone (or the whole) of human body is scanned with ultrasonic waves often?

Ultrasound is considered a safe procedure (reference) which is accepted by the WHO as well (reference). There have been studies however, that show the link of ultrasound treatment to some undesirable traits.

Ultrasound could be possibly linked to a decrease in body weight on birth of infants (reference).

Frequent use of ultrasound may influence babies scanned to grow up left handed (reference)

A significant migration of neurons (change of neurons from their rightful area) has been observed in mice on exposing them to ultrasound at the prenatal stage. (reference).

A study has found detrimental affects to the brains of mice on exposure to ultrasound in the fetal stage (reference).

So based on these papers, I wouldn't call them a 100% safe but these tests all relate to repeated usage of ultrasound imaging. Ultrasound usage sparingly and on valid medical indication should not be a matter of concern.

Benefits and risks of ultrasound in pregnancy

Ultrasound is, arguably, the most commonly used diagnostic procedure in obstetrics. It is convenient, painless, yields immediate, extensive results, and is widely considered to be safe. Some (but not all) benefits described in the literature have been validated by evidence-based analysis, such as pregnancy dating. Others are considered clinically useful, although objective evidence may be less strong. As is the case with almost any medical procedure, however, its performance carries some risks: misdiagnosis on the one hand and possible undesired effects on the other. The general belief exists that diagnostic ultrasound (DUS) does not pose any risk to the pregnant patient nor to her fetus. Nonetheless, ultrasound is a form of energy and, as such, demonstrates effects in biological tissues it traverses (bioeffects). The physical mechanisms responsible for these effects are thermal or non-thermal (mechanical). It is the role of science to show whether any of these bioeffects may be harmful. A risk-benefit analysis may also be important, as well as education of the end users to assure patients' safety.

Keywords: Bioeffects Fetus Mechanical effects Pregnancy Risks Thermal effects Ultrasound.

Ultrasound Scans- Cause for Concern

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, 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 1963 2 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

What is Ultrasound?

The term “ultrasound” refers to the ultra-high frequency soundwaves used for diagnostic scanning. These waves travel at 10 to 20 million cycles per second, compared to10 to 20 thousand cycles per second for audible sound.2 Ultrasound waves are emitted by a transducer (the part of the machine that is put onto the body), and a picture of the underlying tissues is built up from the pattern of “echo” waves which return. Hard surfaces such as bone will return a stronger echo than soft tissue or fluids, giving the bony skeleton a white appearance on the screen.

Ordinary scans use pulses of ultrasound that last only a fraction of a second, with the interval between waves being used by the machine to interpret the echo that returns. In contrast, Doppler techniques, which are used in specialised scans, fetal monitors and hand-held fetal stethoscopes (“sonicaids”) feature continuous waves, giving much higher levels of exposure than ‘pulsed’ ultrasound. Many women do not realise that the small machines used to listen to their baby’s heartbeat are actually using Doppler ultrasound, although with fairly low exposure levels.

More recently, ultrasonographers have been using vaginal ultrasound, where the transducer is placed high in the vagina, much closer to the developing baby. This is used mostly in early pregnancy, when abdominal scans can give poor pictures. However, with vaginal ultrasound, there is little intervening tissue to shield the baby, who is at a vulnerable stage of development, and exposure levels will be high. Having a vaginal ultrasound is not a pleasant procedure for the woman the term “diagnostic rape” was coined to describe how some women experience vaginal scans.

Another recent application for ultrasound is the “nuchal translucency test”, where the thickness of the skin fold at the back of the baby’s head is measured at around 3 months a thick ‘nuchal (neck) fold’ makes the baby more likely, statistically, to have Downs syndrome.

When the baby’s risk is estimated to be over one in 250, a definitive test is recommended. This involves taking some of the baby’s tissue by amniocentesis or chorionic villus sampling. Around 19 out of 20 babies diagnosed as ‘high risk’ by nuchal translucency will not turn out to be affected by Down’s syndrome, and their mothers will have experienced several weeks of unnecessary anxiety.

A nuchal translucency scan does not detect all babies affected by Down’s syndrome. (For more about prenatal testing, see Sarah’s article, on prenatal diagnosis, coming soon as ebook and audio package.)

Information Gained from Ultrasound

Ultrasound is mainly used for two purposes in pregnancy- either to investigate a possible problem at any stage of pregnancy, or as a routine scan at around 18 weeks.

If there is bleeding in early pregnancy, for example, ultrasound may predict whether miscarriage is inevitable. Later in pregnancy, ultrasound can be used when a baby is not growing, or when a breech baby or twins are suspected. In these cases, the information gained from ultrasound may be very useful in decision-making for the woman and her carers. However the use of routine prenatal ultrasound (RPU) is more controversial, as this involves scanning all pregnant women in the hope of improving the outcome for some mothers and babies.

The timing of routine scans (18 to 20 weeks) is chosen for pragmatic reasons. It offers a reasonably accurate due date — although dating is most accurate at the early stages of pregnancy, when babies vary the least in size — and the baby is big enough to see most of the abnormalities that are detectable on ultrasound. However, at this stage, the EDD (expected date of delivery) is only accurate to a week either side, and some studies have suggested that an early examination, or calculations based on a woman’s menstrual cycle, can be as accurate as RPU.9 10

And while many women are reassured by a normal scan, RPU actually detects only between 17 and 85 percent of the 1 in 50 babies that have major abnormalities at birth.11 12 A recent study from Brisbane showed that ultrasound at a major women’s hospital missed around 40 percent of abnormalities, with most of these being difficult or impossible to detect.13 Major causes of intellectual disability such as cerebral palsy and Down’s syndrome are unlikely to be picked up on a routine scan, as are heart and kidney abnormalities.

When an abnormality is detected, there is a small chance that the finding is a “false positive”, where the ultrasound diagnosis is wrong. A UK survey showed that, for one in 200 babies aborted for major abnormalities, the diagnosis on post-mortem was less severe than predicted by ultrasound and the termination was probably unjustified. In this survey, 2.4 percent of the babies diagnosed with major malformations, but not aborted, had conditions that were significantly over or under-diagnosed.14

There are also many cases of error with more minor abnormalities, which can cause anxiety and repeated scans, and there are some conditions which have been seen to spontaneously resolve.15

As well as false positives, there are also uncertain cases, where the ultrasound findings cannot be easily interpreted, and the outcome for the baby is not known. In one study involving women at high risk, almost 10 percent of scans were uncertain.16 This can create immense anxiety for the woman and her family, and the worry may not be allayed by the birth of a normal baby. In the same study, mothers with “questionable” diagnoses still had this anxiety three months after the birth of their baby.

In some cases of uncertainty, the doubt can be resolved by further tests such as amniocentesis. In this situation, there may be up to two weeks wait for results, during which time a mother has to decide if she would 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 baby.17

As well as estimating the EDD and checking for major abnormalities, RPU can also identify a low-lying placenta (placenta praevia), and detect the presence of more than one baby at an early stage of pregnancy. However, 19 out of 20 women who have placenta praevia detected on an early scan will be needlessly worried: the placenta will effectively move up, and not cause problems at the birth. Furthermore detection of placenta praevia by RPU has not been found to be safer than detection in labour.15 No improvement in outcome has been shown for multiple pregnancies either the vast majority of these will be detected before labour, even without RPU.

The American College of Obstetricians, in their 1997 guidelines on routine ultrasound in low-risk pregnancy, conclude

In a population of women with low-risk pregnancies, neither a reduction in perinatal morbidity [harm to babies around the time of birth] and mortality nor a lower rate of unnecessary interventions can be expected from routine diagnostic ultrasound. Thus ultrasound should be performed for specific indications in low-risk pregnancy.18

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,32 and less right-handedness.33-36 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

Two long-term randomised controlled trials, comparing exposed and unexposed childrens’ development at eight to nine years old, found no measurable effect from ultrasound.38 39 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.40 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

Women’s Experiences of Ultrasound

Women have not been consulted at any stage in the development of this technology, and their experiences and wishes are presumed to coincide with, or be less important than, the medical information that ultrasound provides. For example, supporters of RPU presume that early diagnosis and/or termination is beneficial to the affected woman and her family. However the discovery of a major abnormality on RPU can lead to very difficult decision-making.

Some women who agree to have an ultrasound are unaware that they may get information about their baby that they do not want, as they would not contemplate a termination. Other women can feel pressured to have a termination, or at the least feel some emotional distancing from their “abnormal” baby.17 Furthermore, there is no evidence that women who have chosen termination are, in the long term, psychologically better off than women whose babies have died at birth in fact, there are suggestions that the opposite may be true in some cases.43 And when termination has been chosen, women are unlikely to share their story with others and can experience considerable guilt and pain from the knowledge that they themselves chose the loss.

When minor abnormalities are found- which may or may not be present at birth, as discussed above- women can feel that some of the pleasure has been taken away from their pregnancy.

Women’s experiences with ultrasound and other tests used for prenatal diagnosis (eg amniocentesis) are thoughtfully presented in the book The Tentative Pregnancy by Barbara Katz Rothman.44 The author documents the heartache that women can go through when a difficult diagnosis is made-for some women, this pain can take years to resolve. She suggests that the large numbers of screening tests currently being offered to check for abnormalities may make every woman feel that her pregnancy is ‘tentative’ until she receives reassuring results.

To my mind, ultrasound also represents yet another way in which the deep internal knowledge that a mother has of her body and her baby is made secondary to technological information that comes from an ‘expert’ using a machine. Thus the ‘cult of the expert’ is imprinted from the earliest weeks of life.

Furthermore by treating the baby as a separate being, ultrasound artificially splits mother from baby well before this is a physiological or psychic reality. This further emphasises our cultures favouring of individualism over mutuality and sets the scene for possible- but to my mind artificial- conflicts of interest between mother and baby in pregnancy, birth and parenting.

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 the whole story on pregnancy ultrasound, see Dr Buckley’s webinar “Pregnancy Ultrasound”, including a 2016 update to this chapter. Available to GentleNaturalBirth professional members. See all GNB professional webinars here.


1. Wagner M. Ultrasound: more harm than good? Midwifery Today Int Midwife 1999(50):28-30.

2. de Crespigny L, Dredge R. Which Tests for my Unborn Baby?- Ultrasound and other prenatal tests. 2nd ed. Melbourne: Oxford University Press, 1996.

3. Oakley A. The history of ultrasonography in obstetrics. Birth 198613(1):8-13.

4. Martin J, et al. Births: Final data for 2002. National vital statistics reports. Hyattsville MD: National Center for Health Statistics, 2003.

5. Beech BL. Ultrasound unsound? Talk at Mercy Hospital, Melbourne, April 1993.

6. Neilson JP. Ultrasound for fetal assessment in early pregnancy. Cochrane Database Syst Rev 2000(2):CD000182.

7. Senate Community Affairs Reference Group. Rocking the Cradle A report into childbirth procedures. Canberra: Commonwealth of Australia, 1999.

8. Meire HB. The safety of diagnostic ultrasound. Br J Obstet Gynaecol 198794(12):1121-2.

9. Olsen O, Aaroe Clausen J. Routine ultrasound dating has not been shown to be more accurate than the calendar method. Br J Obstet Gynaecol 1997104(11):1221-2.

10. Kieler H, et al. Comparison of ultrasonic measurement of biparietal diameter and last menstrual period as a predictor of day of delivery in women with regular 28 day-cycles. Acta Obstet Gynecol Scand 199372(5):347-9.

11. Ewigman BG, et al. Effect of prenatal ultrasound screening on perinatal outcome. RADIUS Study Group. N Engl J Med 1993329(12):821-7.

12. Luck CA. Value of routine ultrasound scanning at 19 weeks: a four year study of 8849 deliveries. Br Med J 1992304(6840):1474-8.

13. Chan F. Limitations of Ultrasound. Perinatal Society of Australia and New Zealand 1st Annual Congress. Freemantle, Australia, 1997.

14. Brand IR, et al. Specificity of antenatal ultrasound in the Yorkshire Region: a prospective study of 2261 ultrasound detected anomalies ACOG Committee Opinion. Number 297, August 2004. Nonmedical use of obstetric ultrasonography. Br J Obstet Gynaecol 1994101(5):392-7.

15. Saari-Kemppainen A, et al. Ultrasound screening and perinatal mortality: controlled trial of systematic one-stage screening in pregnancy. The Helsinki Ultrasound Trial. Lancet 1990336(8712):387-91.

16. Sparling JW, et al. The relationship of obstetric ultrasound to parent and infant behavior. Obstet Gynecol 198872(6):902-7.

17. Brookes A. Women’s experience of routine prenatal ultrasound. Healthsharing Women: The Newsletter of Healthsharing Women’s Health Resource Service, melbourne 1994/55(3-4):1-5.

18. American College of Obstetricians and Gynecologists. ACOG practice patterns. Routine ultrasound in low-risk pregnancy. Number 5, August 1997. Int J Gynaecol Obstet 199759(3):273-8.

19. American Institute of Ultrasound in Medicine Bioeffects Committee. Bioeffects considerations for the safety of diagnostic ultrasound. J Ultrasound Med 19887(9 Suppl):S1-38.

20. Liebeskind D, et al. Diagnostic ultrasound: effects on the DNA and growth patterns of animal cells. Radiology 1979131(1):177-84.

21. Ellisman MH, et al. Diagnostic levels of ultrasound may disrupt myelination. Exp Neurol 198798(1):78-92.

22. Stanton MT, et al. Diagnostic ultrasound induces change within numbers of cryptal mitotic and apoptotic cells in small intestine. Life Sci 200168(13):1471-5.

23. Mole R. Possible hazards of imaging and Doppler ultrasound in obstetrics. Birth 198613 Suppl:23-33 suppl, p 26.

24. Testart J, et al. Premature ovulation after ovarian ultrasonography. Br J Obstet Gynaecol 198289(9):694-700.

25. Lorenz RP, et al. Randomized prospective trial comparing ultrasonography and pelvic examination for preterm labor surveillance. Am J Obstet Gynecol 1990162(6):1603-7 discussion 1607-10.

26. Newnham JP, et al. Effects of frequent ultrasound during pregnancy: a randomised controlled trial. Lancet 1993342(8876):887-91.

27. Geerts LT, et al. Routine obstetric ultrasound examinations in South Africa: cost and effect on perinatal outcome–a prospective randomised controlled trial. Br J Obstet Gynaecol 1996103(6):501-7.

28. Newnham JP, et al. Doppler flow velocity waveform analysis in high risk pregnancies: a randomized controlled trial. Br J Obstet Gynaecol 199198(10):956-63.

29. Thacker SB. Quality of controlled clinical trials. The case of imaging ultrasound in obstetrics: a review. Br J Obstet Gynaecol 198592(5):437-44.

30. Davies JA, et al. Randomised controlled trial of Doppler ultrasound screening of placental perfusion during pregnancy. Lancet 1992340(8831):1299-303.

31. Stark CR, et al. Short- and long-term risks after exposure to diagnostic ultrasound in utero. Obstet Gynecol 198463(2):194-200.

32. Campbell JD, et al. Case-control study of prenatal ultrasonography exposure in children with delayed speech. Can Med Assoc J 1993149(10):1435-40.

33. Salvesen KA, et al. Routine ultrasonography in utero and subsequent handedness and neurological development. Br Med J 1993307(6897):159-64.

34. Salvesen KA, Eik-Nes SH. Ultrasound during pregnancy and subsequent childhood non-right handedness: a meta-analysis. Ultrasound Obstet Gynecol 199913(4):241-6.

35. Kieler H, et al. Sinistrality–a side-effect of prenatal sonography: a comparative study of young men. Epidemiology 200112(6):618-23.

36. Kieler H, et al. Routine ultrasound screening in pregnancy and the children’s subsequent handedness. Early Hum Dev 199850(2):233-45.

37. Odent M. Where does handedness come from? Handedness from a primal health research perspective. Primal Health Research 19986(1):1-6.

38. Kieler H, et al. Routine ultrasound screening in pregnancy and the children’s subsequent neurologic development. Obstet Gynecol 199891(5 Pt 1):750-6.

39. Salvesen KA, et al. Routine ultrasonography in utero and school performance at age 8-9 years. Lancet 1992339(8785):85-9.

40. Salvesen KA, et al. Routine ultrasonography in utero and subsequent growth during childhood. Ultrasound Obstet Gynecol 19933(1):6-10.

41. Taylor KJ. A prudent approach to ultrasound imaging of the fetus and newborn. Birth 199017(4):218-21, 223 discussion 221-2.

42. Marinac-Dabic D, et al. The safety of prenatal ultrasound exposure in human studies. Epidemiology 200213(3 Suppl):S19-22.

43. Watkins D. An alternative to termination of pregnancy. Practitioner 1989233(1472):990, 992.

44. Rothman B. The Tentative Pregnancy. Amniocentesis and the sexual politics of motherhood. 2nd ed. London: Pandora, 1994.

Fetal Thermal Effects of Diagnostic Ultrasound

Center for Biomedical Physics, Temple University Medical School, Philadelphia, Pennsylvania.

Received April 12, 2007, from the Department of Obstetrics and Gynecology, Rush University, Chicago Illinois USA

Faculty of Health Sciences, University of Sydney, Sydney, New South Wales, Australia

Bath University and Royal United Hospital, Bath, England

SRI International, Molecular Physics Laboratories, Menlo Park, California USA

Department of Radiology, Harvard Medical School, Boston, Massachusetts USA

Center for Biomedical Physics, Temple University Medical School, Philadelphia, Pennsylvania.

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Processes that can produce a biological effect with some degree of heating (ie, about 1°C above the physiologic temperature) act via a thermal mechanism. Investigations with laboratory animals have documented that pulsed ultrasound can produce elevations of temperature and damage in biological tissues in vivo, particularly in the presence of bone (intracranial temperature elevation). Acoustic outputs used to induce these adverse bioeffects are within the diagnostic range, although exposure times are usually considerably longer than in clinical practice. Conditions present in early pregnancy, such as lack of perfusion, may favor bioeffects. Thermally induced teratogenesis has been shown in many animal studies, as well as several controlled human studies however, human studies have not shown a causal relationship between diagnostic ultrasound exposure during pregnancy and adverse biological effects to the fetus. All human epidemiologic studies, however, were conducted with commercially available devices predating 1992, that is, with acoustic outputs not exceeding a spatial-peak temporal-average intensity of 94 mW/cm 2 . Current limits in the United States allow a spatial-peak temporal-average intensity of 720 mW/cm 2 for fetal applications. The synergistic effect of a raised body temperature (febrile status) and ultrasound insonation has not been examined in depth. Available evidence, experimental or epidemiologic, is insufficient to conclude that there is a causal relationship between obstetric diagnostic ultrasound exposure and obvious adverse thermal effects to the fetus. However, very subtle effects cannot be ruled out and indicate a need for further research, although research in humans may be extremely difficult to realize.

This article analyzes thermal effects of fetal ultrasound exposure. The normal core human body temperature is generally accepted to be 37°C with a diurnal variation of ±0.5°C to 1°C, 1 , 2 although 36.8°C ± 0.4°C (95% confidence interval) may be closer to the actual mean for large populations. 3 During the entire gestation, the temperature of the human embryo/fetus is higher than the maternal core body temperature 4 and gradually rises until, in the final trimester (near term), it exceeds that of the mother by 0.5°C. 5 Thermally induced teratogenesis has been shown in many animal studies, as well as several controlled human studies. 6 Edwards 7 and others have shown that hyperthermia is teratogenic for numerous animal species, including the human, and suggested a 1.5°C temperature elevation above the normal value as a universal threshold. 8 An elevated maternal temperature in early gestation has been associated with an increased incidence of congenital anomalies. 9 Tolerance to increased temperature (thermotolerance) is an important aspect of thermal teratogenesis. Thermotolerance is induced by the production of heat shock proteins (HSPs), which occurs (up to a limit) during a relatively slow (10- to 15-minute) temperature increase of the whole body. 10 Diagnostic ultrasound exposures of mammalian embryos or fetuses in vivo and in vitro do not cause a whole-body temperature increase in the mother but can potentially do so in the embryo. In principle, heating with ultrasound could occur so rapidly that the protective effects of HSPs might not come into play. There are data on effects of hyperthermia and measurements of in vivo temperature induced by pulsed ultrasound but not in the human. 11 – 14 These data have been widely reviewed. 15 – 20 However, there is a serious lack of data on the effects of ultrasound while rigorously excluding other confounding factors. A number of epidemiologic studies of possible developmental effects of obstetric ultrasound were performed before 1992, when exposures of the fetus, if anything, were lower on average than they are today. The results overall were negative. Around 1992, the maximum permitted acoustic output of clinical ultrasound instruments operating in the obstetric mode was allowed to increase by a factor of almost 8. 21 Potentially of even greater significance, no report clearly defines the duration of actual exposure. Epidemiology, of course, cannot be expected to reveal subtle effects. Today, ultrasound is so much a part of obstetric care that it would be very difficult to design an ethically acceptable epidemiologic study.

The material in this article will be presented in the following manner: “Definitions,” “Mechanisms of Tissue Heating,” “Measured Temperature Rise in Human Fetal Tissue,” “Intracranial Temperature Elevation,” “Epidemiologic Data,” “Clinical Studies,” “Discussion Regarding Obstetric Issues in the Human,” and “Conclusions and Recommendations.”

Ultrasound: More Harm than Good?

The ultrasound story begins in July 1955 when an obstetrician in Scotland, Ian Donald, borrowed an industrial ultrasound machine used to detect flaws in metal and tried it out on some tumours, which he had removed previously, using a beefsteak as the control. He discovered that different tumours produced different echoes. Soon Donald was using ultrasound not only for abdominal tumours in women but also on pregnant women. Articles surfaced in the medical journals, and its use quickly spread throughout the world.

The dissemination of ultrasound into clinical obstetrics is reflected in inappropriate statements made in the obstetrical literature regarding its appropriate use: “One of the lessons of history is, of course, that it repeats itself. The development of obstetric ultrasound thus mirrors the application to human pregnancy of diagnostic X-rays. Both, within a few years of discovery, were being used to diagnose pregnancy and to measure the growth and normality of the fetus. In 1935 it was said that “antenatal work without the routine use of X-rays is no more justifiable than would be the treatment of fractures“ (Reece, 1935: 489). In 1978: “It can be stated without qualification that modern obstetrics and gynecology cannot be practiced without the use of diagnostic ultrasound“ (Hassani, 1978). Two years later, it was said that “ultrasound is now no longer a diagnostic test applied to a few pregnancies regarded on clinical grounds as being at risk. It can now be used to screen all pregnancies and should be regarded as an integral part of antenatal care“ (Campbell & Little, 1980). On neither of these dates did evidence qualify the speakers to make these assertions.

It is not only doctors who have tried to promote ultrasound with statements that go beyond the scientific data. Commercial interests also have been actively promoting ultrasound, and not only to doctors and hospitals. As an example, an advertisement in a widely read Sunday newspaper (The Times, London) claimed: Toshiba decided to design a diagnostic piece of equipment that would be absolutely safe … .The name: Ultrasound. A consumer organization in Britain complained to the Advertising Standards Authority that Toshiba was making an untrue claim, and the complaint was upheld. In many countries, the commercial application of ultrasound scanning during pregnancy is widespread, offering “baby look“ and “fun ultrasound“ in order to “meet your baby“ with photographs and home videos.

The extent to which medical practitioners nevertheless followed such scientifically unjustified advice, and the degree to which this technology proliferated, can be illustrated by recent data from three countries. In France, in one year three million ultrasound examinations were done on 700,000 pregnant women-an average of more than four scans per pregnancy.

These examinations cost French taxpayers more than all other therapeutic and diagnostic procedures done on these pregnant women. In Australia, where the health service pays for four routine scans, in one recent year billing for obstetrical ultrasound was $60 million in Australian dollars. A 1993 editorial in U.S.A. Today makes the following statement: “Baby’s first picture-a $200 sonogram shot in the womb-is a nice addition to any family album. But are sonograms medically worth $1 billion of the nation’s scarce health-care dollars? That’s the question raised by a United States study released this week. It found the sonograms that doctors routinely perform on healthy pregnant women don’t make any difference to the health of their babies.“

After a technology has spread widely in clinical practice, the next step is for health policymakers to accept it as standard care financed by the official health sector.

Several European countries now have official policy for one or more routine ultrasound scans during pregnancy. For example, in 1980 the Maternity Care Guidelines in West Germany stated the right of each pregnant woman to be offered at least two ultrasound scans during pregnancy. Austria quickly followed suit, approving two routine scans. Do the scientific data justify such widespread use and great cost of ultrasound scanning?

When Is Ultrasound Helpful?

In assessing the effectiveness of ultrasound in pregnancy, it is essential to make the distinction between its selective use for specific indications and its routine use as a screening procedure.

Essentially, ultrasound has proven valuable in a handful of specific situations in which the diagnosis “remains uncertain after clinical history has been ascertained and a physical examination has been performed.“ Yet, considering whether the benefits outweigh the costs of using ultrasound routinely, systematic medical research has not supported routine use.

One of the most common justifications given today for routine ultrasound scanning is to detect intrauterine growth retardation (IUGR). Many clinicians insist that ultrasound is the best method for the identification of this condition. In 1986, a professional review of 83 scientific articles on ultrasound showed that “for intrauterine growth retardation detection, ultrasound should be performed only in a high-risk population.“ In other words, the hands of an experienced midwife or doctor feeling a pregnant woman’s abdomen are as accurate as the ultrasound machine for detecting IUGR. The same conclusion was reached by a study in Sweden comparing repeated measurement of the size of the uterus by a midwife with repeated ultrasonic measurements of the head size of the fetus in 581 pregnancies. The report concludes: “Measurements of uterus size are more effective than ultrasonic measurements for the antenatal diagnosis of intrauterine growth retardation.“

If doctors continue to try to detect IUGR with ultrasound, the result will be high false-positive rates. Studies show that even under ideal conditions, such as do not exist in most settings, it is likely that over half of the time a positive IUGR screening test using ultrasound is returned, the test is false, and the pregnancy is in fact normal. The implications of this are great for producing anxiety in the woman and the likelihood of further unnecessary interventions.

There is another problem in screening for IUGR. One of the basic principles of screening is to screen only for conditions for which you can do something. At present, there is no treatment for IUGR, no way to slow up or stop the process of too-slow growth of the fetus and return it to normal. So it is hard to see how screening for IUGR could be expected to improve pregnancy outcome.

We are left with the conclusion that, with IUGR, we can only prevent a small amount of it using social interventions (nutrition and substance abuse programs), are very inaccurate at diagnosing it, and have no treatment for it. If this is the present state of the art, there is no justification for clinicians using routine ultrasound during pregnancy for the management of IUGR. Its use should be limited to research on IUGR.

Once again it is interesting to look at what happened with the issue of safety of X-rays during pregnancy. X-rays were used on pregnant women for almost fifty years and assumed to be safe. In 1937, a standard textbook on antenatal care stated: “It has been frequently asked whether there is any danger to the life of the child by the passage of X- rays through it it can be said at once there is none if the examination is carried out by a competent radiologist or radiographer.“ A later edition of the same textbook stated: “It is now known that the unrestricted use of X-rays through the fetus caused childhood cancer.“ This story illustrates the danger of assuming safety. In this regard, a statement from a 1978 textbook is relevant: “One of the great virtues of diagnostic ultrasound has been its apparent safety. At present energy levels, diagnostic ultrasound appears to be without injurious effect … all the available evidence suggests that it is a very safe modality.“

That ultrasound during pregnancy cannot be simply assumed to be harmless is suggested by good scientific work in Norway. By following up on children at age eight or nine born of mothers who had taken part in two controlled trials of routine ultrasound in pregnancy, they were able to show that routine ultrasonography was associated with a symptom of possible neurological problems.

With regard to the active scientific pursuit of safety, an editorial in Lancet, a British medical journal, says: “There have been no randomized controlled trials of adequate size to assess whether there are adverse effects on growth and development of children exposed in utero to ultrasound. Indeed, the necessary studies to ascertain safety may never be done, because of lack of interest in such research.“

The safety issue is made more complicated by the problem of exposure conditions. Clearly, any bio-effects that might occur as a result of ultrasound would depend on the dose of ultrasound received by the fetus or woman. But there are no national or international standards for the output characteristics of ultrasound equipment. The result is the shocking situation described in a commentary in the British Journal of Obstetrics and Gynaecology, in which ultrasound machines in use on pregnant women range in output power from extremely high to extremely low, all with equal effect. The commentary reads, “If the machines with the lowest powers have been shown to be diagnostically adequate, how can one possibly justify exposing the patient to a dose 5,000 times greater?“ It goes on to urge government guidelines on the output of ultrasound equipment and for legislation making it mandatory for equipment manufacturers to state the output characteristics. As far as is known, this has not yet been done in any country.

Safety is also clearly related to the skill of the ultrasound operator. At present, there is no known training or certification for medical users of ultrasound apparatus in any country. In other words, the birth machine has no license test for its drivers.

Looking Ahead: Ultrasound and the Future

Although ultrasound is expensive, routine scanning is of doubtful usefulness, and the procedure has not yet been proved to be safe, this technology is widely used, and its use is increasing rapidly without control. Nevertheless, health policy is slow to develop. No country is known to have developed policies with regard to standards for the machines, nor for the training and certification of the operators. A few industrialized countries have begun to respond to the data showing lack of effectiveness for routine scanning of all pregnant women. In the United States, for example, a consensus conference on diagnostic ultrasound imaging in pregnancy concluded that “the data on clinical effectiveness and safety do not allow recommendation for routine screening at this time there is a need for multidisciplinary randomized controlled clinical trials for an adequate assessment.“

Denmark, Sweden, and the United Kingdom have made similar statements against routine screening. The World Health Organisation (WHO), in an attempt to stimulate governments to develop policy on this issue, published the following statement:

“The World Health Organisation stresses that health technologies should be thoroughly evaluated prior to their widespread use. Ultrasound screening during pregnancy is now in widespread use without sufficient evaluation. Research has demonstrated its effectiveness for certain complications of pregnancy, but the published material does not justify the routine use of ultrasound in pregnant women. There is also insufficient information with regard to the safety of ultrasound use during pregnancy. There is as yet no comprehensive, multidisciplinary assessment of ultrasound use during pregnancy, including: clinical effectiveness, psychosocial effects, ethical considerations, legal implications, cost benefit, and safety.

“WHO strongly endorses the principle of informed choice with regard to technology use. The health-care providers have the moral responsibility: fully to inform the public about what is known and not known about ultrasound scanning during pregnancy and fully to inform each woman prior to an ultrasound examination as to the clinical indication for ultrasound, its hoped-for benefit, its potential risk, and alternative available, if any.“

This statement, sadly, is as relevant today. During the 1980s and early 1990s, a number of us were raising questions about both the effectiveness and safety of fetal scanning. Our voice of caution, however, was like a cry in the wilderness as the technology proliferated.

Then, during the course of one month in late 1993, two landmark scientific papers were published. The first paper, a largely randomized trial of the effectiveness of routine prenatal ultrasound screening, studied the outcome of more than 15,000 pregnant women who either received two routine scans at 15 to 22 weeks and 31 to 35 weeks, or were scanned only for medical indications.

Results showed that the mean number of sonograms in the ultrasound group was 2.2 and in the control group (for indication only) was 0.6. The rate of adverse outcome (fetal death, neonatal death, neonatal morbidity), as well as the rate of preterm delivery and distribution of birth weights, was the same for both groups. In addition, in the author’s words: “The ultrasonic detection of congenital abnormalities has no effect on perinatal outcome.“ At last we have a randomized clinical trial of sufficient size to conclude that there is no value to routine scanning during pregnancy.

The second landmark paper, also a randomized controlled trial, looked at the safety of repeated prenatal ultrasound imaging. While the original purpose of the trial was hopefully to demonstrate the safety of repeated scanning, the results were the opposite. From 2,834 pregnant women, 1,415 received ultrasound imaging at 18, 24, 28, 34 and 38 weeks gestation (intensive group) while the other 1,419 received single ultrasound imaging at 18 weeks (regular group). The only difference between the two groups was significantly higher (one-third more) intrauterine growth retardation in the intensive group. This important and serious finding prompted the authors to state: “It would seem prudent to limit ultrasound examinations of the fetus to those cases in which the information is likely to be of clinical importance.“ Ironically, it is now likely that ultrasound may lead to the very condition, IUGR, that it has for so long claimed to be effective in detecting.

Although we now have sufficient scientific data to be able to say that routine prenatal ultrasound scanning has no effectiveness and may very well carry risks, it would be naive to think that routine use will not continue.

Unfortunately, medical doctors are inadequately educated in the basics of scientific method. It will be a struggle to close the gap between this new scientific data and clinical practice.


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  • Chassar Moir, J. (1960). The uses and values of radiology in obstetrics. In F. Browne & McClure-Brown (Eds), Antenatal and Postnatal Care (9th ed.). London: J. & A. Churchill.
  • Cnattingius, J. (1984). Screening for Intrauterine Growth Retardation . Doctoral dissertation, Uppsala University, Sweden.
  • Ewigman, B. G. et al. and RADIUS study group. (1993). Effect of prenatal ultrasound screening on perinatal outcome. New England Journal of Medicine 329(12).
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  • National Institutes of Health. (1984). Diagnostic ultrasound imaging in pregnancy. Consensus Development Conference Consensus Statement 5, No. 1. Washington, D.C.
  • Neilson, J. and Grant, A. (1991). Ultrasound in pregnancy. In I. Chalmers et al. (Eds), Effective Care in Pregnancy and Childbirth . Oxford, England: Oxford University Press.
  • Newnham, J. et al. (1993). Effects of frequent ultrasound during pregnancy: A randomised controlled trial. Lancet .
  • Newnham, J. (1992). Personal correspondence.
  • Oakley, A. (1984). The Captured Womb . Oxford, England: Blackwell Publishing.
  • Reece, L. (1935). The estimation of fetal maturity by a new method of x-ray cephalometry: its bearing on clinical midwifery. Proc Royal Soc Med 18.
  • Salmond, R. (1937). The uses and values of radiology in obstetrics. In F. Browne (Ed), Antenatal and Postnatal Care (2nd ed.). London: J. & A. Churchill.
  • Salveson, K. et al. (1993). Routine ultrasonography in utero and subsequent handedness and neurological development. British Medical Journal 307.
  • World Health Organisation. (1984). Diagnostic ultrasound in pregnancy: WHO view on routine screening. Lancet 2.

Excerpted and adapted from Pursuing the Birth Machine: The Search for Appropriate Birth Technology , copyright 1994 by Marsden Wagner, published by ACE Graphics. Available in the United States and Canada from the ICEA Bookcenter, (800) 624-4934 Fax (612) 854-8772.

Are Prenatal Ultrasounds Dangerous?

Several questionable sources are spreading alarms about the possible dangers of prenatal ultrasound exams (sonograms). An example is Christine Anderson’s article on the ExpertClick website. In the heading, it says she “Never Liked Ultrasound Technology.”

[She] has never been sold on the safety using Ultrasounds for checking on the fetuses of pregnant women, and for the last decade her fears have been confirmed with a series of studies pointing to possible brain damage to the babies from this technology.

Should We Believe Her?

Should we avoid ultrasounds because Anderson never liked them? Should we trust her judgment that her fears have been confirmed by studies? Who is she?

“Dr.” Christine Anderson is a pediatric chiropractor in Hollywood who believes a lot of things that are not supported by science or reason. Her website mission statement includes

We acknowledge the devastating effects of the vertebral subluxation on human health and therefore recognize that the spines of all children need to be checked soon after birth, so they may grow up healthy.

It also states that “drugs interfere… and weaken the mind, body, and spirit.” Anderson is a homeopath, a craniosacral practitioner, a vegan, and a yoga teacher. She advises her pregnant patients to avoid toxins by only drinking filtered water and only eating organic foods. She sells her own yoga DVD.

In her own pregnancies she refused ultrasound and other prenatal screening tests. This was her idiotic reasoning:

I trusted in my body’s innate wisdom that if the pregnancy was moving forward, then everything was going OK in my baby’s development.

Apparently on her planet if a pregnancy has not spontaneously aborted that means the baby is developing normally, and no abnormal child is ever born. And perhaps all the children are above average?

She believes in many alleged benefits of chiropractic that are not substantiated by any evidence. She says that our emotions create chemical changes in our bodies that can affect our developing babies and that chiropractic helps to keep those feel good chemicals flowing freely. She believes that chiropractic frees up any interference to the nervous system and since the nervous system controls all the functions in the body, chiropractic manipulations allow the organs to optimally process any toxins they encounter. She believes getting regular chiropractic care reduces labor times.

Based on this, I am not impressed by her medical judgment or her understanding of biology or science, but that doesn’t necessarily mean she is wrong about ultrasound. What does she say?

Alleged Risks of Ultrasound According to Anderson

  • Ultrasound heats the tissue and researchers suspect that the waves cause small local gas pockets which vibrate and collapse called cavitation. The gas can reach up to temperatures of thousands of degrees (Celsium) [sic] leading to production of potentially toxic chemical reactions.
  • Studies done on mice have shown intestinal bleeding caused by changes in the cells. Scientists conclude that there would be similar effects in humans.
  • Ultrasound has been linked to the following abnormalities:
    • Left handedness in children who are supposed to be right-handed. Although there is nothing inherently wrong with being left handed, the change is attributed to a subtle damage to the brain. Males are more affected than female fetuses, probably because the male brain develops later.
    • Early labor, premature birth, miscarriage, low birth weight, poorer health at birth, and perinatal death.
    • Increased learning disabilities, epilepsy, delayed speech development, dyslexia

    She also alleges that no studies have been done to prove the safety of these devices. This is demonstrably false.

    Risks According to Scientists

    Obstetricians and radiologists who have evaluated the peer-reviewed literature have found no evidence of harm except for an apparent correlation between ultrasound exposure and left-handedness (in males only!). Such odd-sounding correlations are usually not significant, and are mostly good for a chuckle.

    Experts place little reliance on the mouse studies, since the dosages tested were higher than what humans are exposed to and since no corresponding clinical consequences have been detected in humans. Nevertheless, they acknowledge theoretical reasons for concern, and they recommend that medically unnecessary ultrasounds be avoided under the precautionary principle.

    Does Routine Ultrasound Affect Outcomes?

    A large study (15,530 women) published in The New England Journal of Medicine found that routine screening did not reduce perinatal morbidity and mortality. There were no significant differences in the rate of preterm delivery, distribution of birth weight, or outcomes within the subgroups of women with multiple gestations, small-for-gestational-age infants, and post-date pregnancies. Finally, the detection of major anomalies by ultrasound examination did not alter outcomes. The authors pointed out that routinely screening more than 4 million pregnant women annually in the United States at $200 per scan would increase costs by more than $1 billion.

    A Finnish study found that perinatal mortality was significantly lower in the screened than in the control group (4.6/1000 vs 9.0/1000) but this was attributed to improved early detection of major malformations which led to induced abortion. All twin pregnancies were detected before the 21st gestational week in the screening group compared with 76.3% in the control group perinatal mortality in the small series of twins was 27.8/1000 vs 65.8/1000, respectively.

    Caveats: These studies did not look for long-term consequences like learning disabilities. And there are other considerations besides morbidity and mortality. Ultrasound can reassure patients or allow them to plan ahead for multiple births or abnormal infants, and it can guide obstetric management.

    Reasons for Doing Ultrasounds

    Ultrasounds can detect fetal abnormalities and can help guide obstetric care by detecting problems like multiple fetuses and placenta previa. There are many legitimate reasons for doing them, especially in high-risk pregnancies or when a specific problem is suspected.

    Reasons for Not Doing Routine Ultrasounds

    False alarms can be raised. Apparent abnormalities may cause worry but turn out not to be significant. Placenta previa detected early in pregnancy frequently resolves before delivery.

    There is no way to completely rule out the possibility of a low risk of long-term consequences. Trying to identify such consequences by even the most careful epidemiologic studies is fraught with pitfalls, since if you look for every possibility you will inevitably find a few spurious correlations. Experts agree that routine ultrasound screening is not necessary in low-risk pregnancies and that ultrasounds for nonmedical reasons should be discouraged.

    Some nonmedical uses are particularly objectionable. Ultrasounds are being used in India and elsewhere to determine sex for the purpose of aborting undesired female fetuses. Ultrasound is being commercially promoted for “keepsake” pictures and movies like this 5 minute video. Tom Cruise was roundly criticized by doctors for buying his own ultrasound machine for home use.

    There is no reason to fear prenatal ultrasounds that are ordered by science-based medical professionals and performed by qualified technicians, but it seems prudent to exercise caution and not do them for frivolous reasons.

    Considering that Anderson practices homeopathy, subluxation-based chiropractic, and craniosacral therapy, disparages drugs, and manipulates the spines of newborn infants, I think her own practices are far more worrisome than the ultrasounds she fears.

    Is Your Doctor Ordering Too Many Ultrasounds?

    Summary: Moms-to-be are getting more ultrasounds than is medically indicated &mdash an average of 5.2 per delivery, up 92 percent since 2004, according to new data reported on by The Wall Street Journal. The American College of Obstetricians and Gynecologists (ACOG) recommends getting one to two scans per low risk pregnancy &mdash and it's estimated that 75 percent of all pregnancies are considered low-risk.

    For moms-to-be, ultrasounds are often the most exciting part of your doctor's visit. Not only do you get to see your little bundle of joy for the first time, there's some peace of mind in knowing that he's safe and healthy inside of you. Ultrasounds can also serve as a bonding tool, to let new moms know that this is really happening &mdash those daily kicks are actually your growing baby. But although seeing your little guy or girl is reassuring and exciting, experts warn against getting too many ultrasounds when they're not medically necessary.

    According to research analyzed and reported on by The Wall Street Journal and compiled by the non-profit FAIR Health, doctors gave an average of 5.2 ultrasounds per delivery. The study included more than 150 million individuals, some of whom were high-risk patients. That means the number could have been inflated because high-risk pregnancies &mdash for example, moms-to-be with chronic conditions like type 2 diabetes,high blood pressure, lupus or growth restricted fetuses &mdash often require more constant scanning.

    That said, although high-risk pregnancies do require more frequent ultrasounds, an estimated three in four pregnancies are low-risk. Experts recommend that additional scans should not be used unless necessary or for recreational purposes to provide a sneak peak at baby. So while fetal ultrasounds are considered safe when used infrequently, we don't know the long-term side effects for sure, according to Dr. Jeffrey A. Kuller, Professor of Obstetrics and Gynecology in the Division of Maternal-Fetal Medicine at Duke University Medical Center. That's mostly because no scientist would knowingly put a fetus at risk of potential harm to study the effects of ultrasounds.

    ACOG recommends one to two ultrasounds per pregnancy:

    • An earlyultrasound at 10 to 12 weeks to establish due date and whether the pregnancy is viable. This scan is used to confirm the fetal heartbeat and a uterine (as opposed to ectopic or tubular) pregnancy, for example.
    • A more detailedanatomy scanat 18 weeks to screen for fetal growth, placenta location and umbilical cord, as well as the baby's general health and anatomy.

    Additional ultrasounds, including 3D and 4D ultrasounds, should only be performed if the mother is considered high-risk or if there's a suspected fetal abnormality &mdash which means you should avoid those offered outside a doctor's office as keepsakes along with at-home Doppler ultrasound machines.

    Dr. Kuller says that beyond these necessary scans, ultrasounds have the potential for negative, unintended risks.

    "While fetal weight is reasonably accurate, within about 10 percent, if the ultrasound under-estimates or over-estimates weight, patients can end up with unnecessary C-sections or premature deliveries in some cases," says Dr. Kuller. "Patients should also be warned that doctors can't rule out all defects or chromosomal abnormalities using ultrasound."

    A variety of factors seem to be contributing to the dramatic increase in ultrasound scans. Increased pressure from patients who want both a keepsake of their baby-to-be and assurance that he or she is thriving inside the womb are part of the picture, but Dr. Kuller contends there's more to it.

    "We live in a medical climate where doctors are constantly afraid of getting sued," he says. "Scans give patients and doctors assurance that things are good, and fear of litigation pushes doctors to do more testing in everything, including ultrasounds. I think the average patient is probably getting scanned more than they need to be."

    What this means to you. There's no doubt about it: A view inside the womb is exciting! And since it's impossible to know for sure what's going on in there otherwise, seeing your baby moving on-screen can put to rest some fears. However we don't know the long-term side effects of ultrasounds on the developing fetus for sure, which means unnecessary scans could have some unintended consequences. The best plan of action? Get a scan at 10 to 12 weeks and another at 18 weeks, per ACOG's recommendations. If your doctor requests more than that, ask questions and make sure what you're receiving is medically necessary for the optimal health of your baby-to-be.

    Side effects of ultrasound therapy

    Ultrasound therapy is used for treating many conditions such as cancers, tumors, dental conditions, and many others. In most of these, ultrasound is used physically, to establish diagnosis or to provide an image of certain internal organs or parts of our body, making it easy to track down any problems or possible illnesses. However, it can also be used when fighting tumors or relaxing one’s body, though these cases are far less frequent.

    The Good Side

    The ultrasound has two good sides. Firstly, it is an excellent tool for fighting cancerous cells, cysts, tumors, bacteria and numerous others. Secondly, it is known to speed up the healing process of our organism significantly, some claiming that in certain situations it provides even a 30% faster healing process.

    The Bad Side

    Unfortunately, there are those as well. One of them is the so called “cavitation”. This mainly manifests through pain and burning sensation the patient feels during exposure. Namely, the gas in the nuclei of our tissue cells gets heated, thus causing this pain and discomfort or even nausea, breathing problems and disorientation.

    We see that even though most doctors claim this therapy to be completely safe and recommended, there may be certain problems caused by it. Regardless, any overexposure to these sound frequencies may be dangerous. That being said, if pain and or kind of discomfort are felt during the ultrasound treatment, one should complain immediately and stop the treatment since the frequencies, if wrong, may cause permanent tissue damage and may even harm one’s nervous system.

    Furthermore, this therapy should not be applied over certain body parts or under some specific conditions. Pregnant women or women having their periods should not have their pelvic regions, their lower abdomen or back exposed to ultrasound treatment. Also, our eyes, sex organs or female breasts are not suitable for this treatment. Ultrasound frequencies should not be applied over certain bone fracture, skin wounds or malignant tumors of any sorts. Additionally, people with pacemakers or breast implants should avoid ultrasound as well.

    Finally, even though the ultrasound treatment has proven to be quite effective, some still doubt it’s worthiness claiming that it does nothing that other similar treatments involving heat or stretching could not do. There have also been cases of diverse efficiency, where the therapy worked on some people, while on others it did not.

    The most important thing is that it can and is beneficial and life-saving in some cases. Nevertheless, one should bear in mind all the negative sides of it and be careful, using only the best the ultrasound treatment has to offer.

    Studies have shown that ultrasound is generally safe. There are no known harmful side effects and there is virtually no discomfort during the test. In addition, ultrasound does not use radiation, as X-ray tests do. Although there are no known risks, ultrasound can heat up tissues in the body slightly and can also cause small gas pockets (known as cavitation) to form. The possible long-term effects of these are not known.

    Before the Ultrasound

    Generally, no special preparation is needed for an ultrasound. Depending on the type of test, you may need to drink fluid before the ultrasound or you may be asked to fast for several hours before the procedure.

    Future trends of imaging in cancer

    There are extraordinary future opportunities for imaging techniques in tumor biology evaluation, including the development of imaging biomarkers and radiomics/radiogenomics, the use of multiparametric analysis and artificial intelligence, and theranostic. To date, most research has been focusing on validating biomarkers extracted from tissue or blood samples, which has improved patient stratification and assisted oncologic drug development. Imaging techniques can evolve into clinically useful biomarkers for tumor assessment and evaluation of therapy response. The advantages of imaging are its versatility, its widespread disponibility, its capability of evaluating whole tumor burden, and its relatively noninvasive nature [140,141,142,143,144]. Adequate quantification of imaging biomarkers is of paramount importance when extracted data are going to be used in patient management. In this setting, data must be reproducible and the technology used to extract them must be standardized. Biomarkers precise a complex process of validation and qualification [140, 143]. On the other side, in recent years, imaging has been boosted by the technological development generating a large volume of data. Such information has increased in complexity and may offer prognostic value and may reveal meaningful information for decision-support in cancer diagnosis and treatment. Radiomics refers to the extraction and quantitative analysis of tumor characteristics from medical images. On its part, radiogenomics investigates the relationship between imaging features and gene expression. The -omic approach is based on numerical calculus and computer science methods, allowing the management and analysis of a very large number of variables for each sample and modality. There is a rapid increase in the number of publications that have highlighted the utility of imaging -omics in many different tumor types and based on different imaging techniques [145,146,147,148,149,150,151,152,153,154,155]. Radiomics and radiogenomics approaches may show clinical utility for assisting in cancer diagnosis, assessment of tumor aggressiveness, response assessment, and evaluation of patients’ outcome. Integrating (quantitative) imaging data with other relevant information (clinical, pathological, etc.) and multi-omics (genomics, proteomics, and metabolomics) will be essential for unraveling tumor heterogeneity and making real-time clinical decisions for patients in personalized medicine. However, this process still necessitates improvement and standardization in order to achieve routine clinical adoption. In this scenario, computers may be useful tools for the assessment of tumor characteristics and for the evaluation of therapy response. Computers can learn (machine learning) to extract meaningful patterns (including patterns that are beyond human perception) by processing massive datasets (big data) through mathematical models (algorithms). Machines can also correct algorithm mistakes by training. Machine learning algorithms are just useful components of computer-aided diagnosis and decision support system in oncology. Imaging representation and interpretation of tumor biology will require computational models to understand and predict the complex nonlinear dynamics that result in combinations of imaging features [156,157,158]. 3D printing is also an emerging computer-based technique that may be useful in oncology for research, surgical planning (using an exact 3D model of the patient’s organs to practice a procedure), device designing and manufacturing, and tissue or organ replacement [159]. The analysis of multi-dimensional imaging datasets is also increasingly required for imaging tumor phenotype. The correlation between imaging features obtained with different techniques must be explored for understanding the underlying tumor biology (Fig. 21). Significant differences in vascular, physiological, and metabolic characteristics have been identified in metastatic and nonmetastatic cancers. In this setting, high glycolytic activity and poor perfusion (vascular-metabolic mismatch) result in an aggressive tumor phenotype [160]. Finally, advances in the understanding of cancer biology together with developments in diagnostic technologies, and expansion of therapeutic options have all contributed to the concept of personalized cancer care with accurate and specific targeting of cancer cells. Theranostics is the systematic integration of targeted diagnostics and therapeutics. Imaging may select the therapeutic choice and may monitor subsequent changes in the biological characteristics of the tumor [161, 162].

    In conclusion, clinical imaging has tremendous potential in the evaluation of a wide spectrum of biological tumor characteristics at all stages of a cancer patient’s management and in drug discovery. Imaging techniques have also the ability to show the spatial and temporal heterogeneity of tumors (Fig. 22). In the time of precision oncology, clinical imaging represents a basic decision-making tool in cancer patients.

    Colorectal cancer liver metastasis in a 56-year-old man. FDG-PET (left) and b500 diffusion-weighted (middle) images demonstrated the presence of a mismatch between the obtained parameters. Note that the size of the FDG abnormality is smaller than the diffusion one (black arrow) (right). Tumor biology may explain this feature. Higher FDG uptake occurs at the edge of the necrotic cavity (white arrow) which is of relative low SI on b500 image. The edge of the necrotic cavity usually represents an area of relative tumor hypoxia, which may promote a high metabolic activity (vascular metabolic-mismatch). On its part, the periphery of the mass generally presents good perfusion and it is the most cellular area of the tumor, explaining the restricted diffusion at this level

    Whole-body DWI evaluation in a 72-year-old man with metastatic prostate cancer treated with (docetaxel + prednisone). A comparison between images pre (left) and posttherapy (right) demonstrated that tumor volume decreased (1280 cm 3 → 640 cm 3 ) and mean ADC moved from 0.7 to 1.61 confirmed an increasing % of voxels at higher ADC values after therapy consistent with reductions in cellularity due to tumor necrosis. However, tumor response was heterogeneous in this patient and there were some anatomical areas that presented a limited tumor response (black dotted circle on lumbar spine and black arrows)

    Watch the video: Sonongraphie Grundlagen: Knobologie unserer Kursgeräte (January 2022).