Prenatal Ultrasound
The use of ultrasound has dramatically increased
in prenatal care. Its safety and efficacy are still highly
questionable. Even the FDA says, "While ultrasound has been
around for many years, expectant women and their families
need to know that the long-term effects of repeated ultrasound
exposures on the fetus are not fully known." http://www.fda.gov/fdac/features/2004/104_images.html
Most
studies and authorities recommend that ultrasound is safe
only when "medically necessary". The question
really comes down to personal practitioner selection: "what
warrants medical necessity?" Here is where interpretation
is vast and undefined. While ACOG recommends that ultrasound
examinations be done for specific reasons, such as a suspected
ectopic pregnancy, a possible miscarriage or detection of
possible birth defects, many physicians include one examination
as part of routine care, at 18 to 20 weeks of pregnancy.
The March of Dimes Birth Defects Foundation estimates that
70 percent of American women have at least one ultrasound
examination during their pregnancy.
Perhaps a more prudent
approach would be to define medical necessity as "life saving" and forgo prenatal
ultrasound procedures for less relevant reasons. The original
axiom of medicine "first do no harm" should always beconsidered
when determining "medical necessity" for ultrasound.
" Lack
of risk has been assumed because no adverse effects have
been demonstrated clearly in humans. However, other evidence
dictates that a hypothetical risk must be presumed with ultrasound.
Like-wise, the efficacy of many uses of ultrasound in improving
the management and outcome of pregnancy also has been assumed
rather than demonstrated, especially its value as a routine
screening procedure." http://www.ob-ultrasound.net/joewoo3y.html
In
accordance with medical protocol, the safety and efficacy
of prenatal ultrasound has not yet been proven via peer reviewed
research. On the contrary, current studies are cautioning
its use. Prenatal ultrasound, therefore may even be considered, "experimental
and investigational".
Concerned with nerve system stress,
doctors of chiropractic are always on the look out for procedures
that may cause more damage than benefit. Now a new study
presents data we have suspected all along: ultrasound may
affect brain development.
Ultrasound Can Affect Brain Development
A new study warns,
exposure to ultrasound can affect fetal brain development.
Head researcher Pasko Rakic, chairman of the neurobiology
department at Yale University School of Medicine. Although
Rakic says, "Our study in mice
does not mean that use of ultrasound on human fetuses for
appropriate diagnostic and medical purposes should be abandoned" he
did, however add that women should avoid unnecessary ultrasound
scans until more research has been done.
The study, funded by the National Institute of Neurological Disorders and Stroke
revealed that when pregnant mice were exposed to ultrasound, a small number
of nerve cells in the developing brains of their fetuses failed to extend correctly
in the cerebral cortex. The paper added that the since the developmental period
of these brain cells is much longer in humans than in mice, that exposure would
be a smaller percentage of their developmental period. However, the authors
also made it clear that brain cell development in humans is also more complex
than in mice and with more cells developing, the chances of developmental mishaps
could be increased.
In Rakic's study, pregnant mice were exposed
to ultrasound for various amounts of time ranging from a
total exposure of 5 minutes to 420 minutes. The brains of
the newborn baby mice were studied and compared with those
of mice whose mothers had not been exposed to ultrasound.
The study of 335 mice concluded that in those whose mothers
were exposed to a total of 30 minutes or more, "a small but statistically significant number" of
brain cells failed to grow into their proper position and remained scattered
in incorrect parts of the brain. The number of affected cells increased with
longer exposures.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=
AbstractPlus&list_uids=16901978&query_hl=3&itool=pubmed_docsum
Obstetric ultrasound biological effects and safety.
J Obstet Gynaecol Can.
2005 Jun;27(6):572-80.
OBJECTIVE: To review the biological effects and safety
of obstetric ultrasound.
OUTCOME: Outline the circumstances in which safety may be a concern with obstetric
ultrasound.
BENEFITS, HARMS, AND COSTS: Obstetric ultrasound should only be done for
medical reasons, and exposure should be kept as low as reasonably achievable
(ALARA) because of the potential for tissue heating. Higher energy is of
particular concern for pulsed Doppler, colour flow, first trimester ultrasound
with a long transvesical path (> 5 cm), second or third trimester exams
when bone is in the focal zone, as well as when scanning tissue with minimal
perfusion (embryonic) or in patients who are febrile. Operators can minimize
risk by limiting dwell time, limiting exposure to critical structures, and
following equipment generated exposure information.
Recommendations
1. Obstetric ultrasound should only be used when the potential medical benefit
outweighs any theoretical or potential risk (II-2A).
2. Obstetric ultrasound should not be used for nonmedical reasons, such as
sex determination, producing nonmedical photos or videos, or for commercial
purposes ( III-B).
3. Ultrasound exposure should be as low as reasonably achievable (ALARA) because
of the potential for tissue heating when the thermal index exceeds 1. Exposure
can be reduced through the use of output control and (or) by reducing the amount
of time the beam is focused on one place (dwell time) (II-1A).
4. All diagnostic ultrasound devices should comply with the output display
standards (MI and TI) (III-B).
5. When ultrasound is done for research or teaching purposes, exposed individuals
should be informed if either the MI or TI are greater than 1 and how this exposure
compares to that found in normal diagnostic practice (III-B). 6. While imaging
the fetus in the first trimester, Doppler and colour Doppler should be avoided
(III-B).
Does Ultrasound Improve Perinatal Outcome?
Many clinicians advocate routine ultrasound
screening during pregnancy to detect congenital anomalies,
multiple-gestation pregnancies, fetal growth disorders, placental
abnormalities, and errors in the estimation of gestational
age. However, it is not known whether the detection of these
conditions through screening leads to interventions that
improve perinatal outcome. The rates of preterm delivery
and the distribution of birth weights were nearly identical
in the two groups. The ultrasonographic detection of congenital
anomalies had no effect on perinatal outcome. There were
no significant differences between the groups in perinatal
outcome in the subgroups of women with post-date pregnancies,
multiple-gestation pregnancies, or infants who were small
for gestational age. Screening ultrasonography did not improve
perinatal outcome as compared with the selective use of ultrasonography
on the basis of clinician judgment.
Ewigman BG, Crane JP, Frigoletto FD Effect
of prenatal ultrasound screening on perinatal outcome N
Engl J Med. 1993 (Sep 16); 329 (12): 821-827
Another
study from Norway looks at outcomes of antenatal ultrasound
diagnosis in thirty-six children with serious congenital
problems. It sought to determine how many of the problems
were detected by ultrasound before birth, and whether
outcomes were better when the problem was known before
birth than for babies where the problem was missed on
the ultrasound and not seen until after delivery. The
women had had an average of five scans, but the average
was seven in women who had a problem detected. Only two of
eight congenital diaphragmatic hernias were picked up on
ultrasound, half the cases of abdominal wall defects (six
our of twelve), five of thirteen cases of meningomyelocele
and none of the three cases of bladder extroversion.
All thirteen
babies with prenatal diagnosis were delivered by cesarean
section. Nineteen of the twenty-three with postnatal diagnosis
had an uncomplicated vaginal delivery. Those with prenatal
diagnosis had shorter gestational age (about two weeks),
lower birthweights, and slightly lower Apgar scores. Three
out of thirteen (23 percent) died compared with one out of
twenty-three (4 percent) of those diagnosed after birth.
AIMS
Journal, Vol. 10 No. 2
Does the Exposure to Ultrasound Relate to Delayed Speech
in Children?
The purpose of this study was to determine
whether there is an association between prenatal ultrasound
exposure and delayed speech in children. The results showed
that the children with delayed speech had a higher rate of
ultrasound exposure than the control subjects. The findings
suggest that a child with delayed speech is about twice as
likely as a child without delayed speech to have been exposed
to prenatal ultrasound waves The authors concluded that an
association between prenatal ultrasonography exposure and
delayed speech was found. If there is no obvious clinical
indication for diagnostic in-utero ultrasonography, physicians
might be wise to caution their patients about the vulnerability
of the fetus to noxious agents.
Campbell JD, Elford RW, Brant
RF Case-control
study of prenatal ultrasonography exposure in children
with delayed speech CMAJ 1993 (Nov
15); 149 (10): 1435-1440
Does Diagnostic Ultrasound affect Mylenation?
Neonatal rats 3 to 5 days of age were exposed
to the ultrasound beam from a medical ultrasound imaging
system. Dorsal nerve roots were examined by electron microscopy.
Comparison between exposed and sham-exposed controls revealed
disruption of the nodes of Ranvier attributable to ultrasound.
Morphologic changes ranged from vacuole formation in the
paranodal region to frank demyelination and were still evident
after 24 h of recovery. Rats of this age are at a stage of
myelination similar to that of a human fetus 4 to 5 months.
The ultrasound intensities used in this study are consistent
with those used for human imaging (SPTA 0.135 mW/cm2, SATA
0.045 mW/cm2, SPTP 8.7 W/cm2, SPPA 1.9 W/cm2), but the relevance
of these findings to clinical ultrasound will require further
study.
Ellisman MH, Palmer DE, Andre MP Diagnostic
levels of ultrasound may disrupt myelination Exp
Neurol. 1987 (Oct); 98 (1): 78-92
Does Ultrasound
Cause Genetic Damage?
After a single exposure to diagnostic ultrasound
there are long lived effects on the DNA of the cells, on
the behavior of the cells, and on cell growth that persists
for many generations. These are changes in cell structure
that have persisted over 10 generations The results confirm
previous findings indicating that ultrasound of diagnostic
intensities can affect the DNA of animal cells.
Sister
chromatid exchanges in human lymphocytes after exposure
to diagnostic ultrasound Science
1979 (Sep 21); 205 (4412): 1273-1275
Ultrasound
in the diagnostic range appears to cause detectable effects
on DNA and growth patterns of animal cells.
Liebeskind D, Bases
R, Elequin F Diagnostic
ultrasound: effects on the DNA and growth patterns of
animal cells Radiology 1979 (Apr); 131
(1): 177-184
Does Ultrasound in Labor have an Adverse
Effect on Maternal Red Blood Cells?
Blood samples were taken before and after Doppler
monitoring. There was a trend toward increased fragility
in patients exposed continuously for more than seven hours.
Doppler
ultrasound and maternal erythrocyte fragility Obstet
Gynecol 1983 (Jul); 62 (1): 7-10
Risks of Ultrasound
Scanning by Beverley Beech
- Davies: 16 perinatal deaths compared with 4 perinatal deaths in the control group
- Lorenz: Preterm labour was more than doubled in the ultrasound group--52% compared with 25% in the controls.
I do not agree with the statement that "a lot
of embryos have been exposed to ultrasound over the last
25 years with no documented ill effects." Lieberskind's research
indicated changes in cell structure that persisted over 10
generations and although researchers attempted to rubbish
the research it was repeated by other researchers, and now
we have research from Ireland that also shows affected cells.
There
is a widespread assumption that ultrasound is beneficial,
yet there is no evidence that infant outcomes have been improved
by routine ultrasound examinations. Researchers have enthusiastically
focused on what ultrasound could find but have paid little
or no attention to the potential adverse long-term effects.
As a result, despite ultrasound being enthusiastically used
over the last 30 years, there is no good research that addresses
the anxieties that ultrasound may be responsible for dyslexia,
learning difficulties and behavioral problems.
The Saari Kempaainen
study revealed that 150 women were diagnosed as having placenta
previa; when they got to term only 4 women actually had it.
In the control arm the women who were not exposed to ultrasound
also had 4 women whose placenta praevias were discovered
when they went into labour. Both sets of women had caesarean
sections and there was no difference in outcomes. The researchers
did not investigate the amount of stress a diagnosis of placenta
praevia could have caused in the 146 misdiagnosed women.
This research shows that early diagnosis of placenta praevia
is irrelevant and a complete waste of time, yet doctors and
midwives persist in telling women they have low lying placentas.
A
study by Jahn revealed that out of 2,378 pregnancies, only
58 of 183 growth retarded babies were diagnosed before birth,
and 45 fetuses were wrongly diagnosed as being growth retarded
when they were not. Only 28 of the 72 severely growth-retarded
babies were detected before birth. Furthermore, the diagnosed
babies were more likely to be delivered by caesarean section
(44.4%) compared with 17.4% for the babies who were not small
for dates. If a baby actually had IUGR the section rate varied
hugely according to whether it was diagnosed before birth
(73.1% sectioned) or not (30.4%). Preterm delivery was 5
times more frequent in those whose IUGR was diagnosed before
birth than those who were not. The average diagnosed pregnancy
was 2.3 weeks shorter than the undiagnosed one. The admission
rate to intensive care was 3 times higher for the diagnosed
babies. This important study provides further evidence that
scans are not benefiting babies or those mothers who were
subjected to caesarean sections.
This Article was originally
printed in Midwifery E-News at: http://www.midwiferytoday.com/enews/enews1n31.asp
Scroll down to "4) Risks of Ultrasound
Scanning"
References:
Davies JA, Gallivan S, Spencer JA Randomised
controlled trial of Doppler ultrasound screening of placental perfusion during
pregnancy Lancet 1992 (Nov 28); 340 (8831): 1299-1303
Jahn A, Razum O, Berle P Routine
screening for intrauterine growth retardation in Germany: low sensitivity and
questionable benefit for diagnosed cases Acta Obstet Gynecol Scand.
1998 (Jul); 77 (6): 643-648
Liebeskind D, Bases R, Elequin F Diagnostic
ultrasound: effects on the DNA and growth patterns of animal cells Radiology
1979 (Apr); 131 (1): 177-184
Lorenz RP, Comstock CH, Bottoms SF Randomized
prospective trial comparing ultrasonography and pelvic examination for preterm
labor surveillance Am J Obstet Gynecol 1990 (Jun); 162 (6): 1603-1607
Olsen O and Clausen JE Routine ultrasound dating has not been shown
to be more accurate than the calendar method British Journal of Obstetrics
and Gynaecology 1997 (Nov); 104: 1221-1222
Saari-Kemppainen A, Karjalainen O, Ylostalo P Ultrasound
screening and perinatal mortality: controlled trial of systematic one-stage
screening in pregnancy. The Helsinki Ultrasound Trial Lancet 1990
(Aug 18); 336 (8712): 387-391
Taskinen H, Kyyronen P, Hemminki K Effects
of ultrasound, shortwaves, and physical exertion on pregnancy outcome in physiotherapists J
Epidemiol Community Health. 1990 (Sep); 44 (3): 196-201
Other Websites/ Articles For Making Informed Choices about
Ultrasound:
Ultrasound:
Weighing the Propaganda Against the Facts
Another, very complete, well referenced article by Beverly Lawrence Beech can
be found in Midwifery Today Archives: http://www.midwiferytoday.com/articles/ultrasound.asp
Prenatal
Testing: Ultrasound
Safety and Accuracy
A thorough and infomative article on ultrasound.
Read it here: http://www.plus-size-pregnancy.org/Prenatal%20Testing/prenataltest-ultrasoundsafety.htm#The%20Basic%20Issues
How
Sound is Ultrasound?
Read it here: http://www.midwiferytoday.com/enews/enews0105.asp
On
the "safety" amd "usefulness" of prenatal ultrasound
Read it here: http://www.alternamoms.com/ultrasound.html
Screening Ultrasonography
in Pregnancy
Read it here: http://cpmcnet.columbia.edu/texts/gcps/gcps0046.html
Excerpt from the National
Institutes of Health Consensus Development Conference Statement -- February
6-8, 1984
Think Ultrasound for Babies Is Safe ?
Article by Leigh Dundass
News Flash: Research shows ultrasounded populations
have a quadrupled perinatal death rate, increased rates of
brain damage, dyslexia, speech delays, epilepsy, learning
difficulties, and a 32% increase in left handedness (which
is thought to be caused by brain damage).
- Perinatal death rate quadrupled in ultrasounded group. (2,475 woman study by Davies et al., 1993); Midwifery Today .
- 1984 study shows ultrasounded babies developed more dyslexia, and twice as often showed delayed speech of unknown causes. (Stark et al 1984); Midwifery Today ; Effects of Frequent Ultrasound During Pregnancy: A Randomized Controlled Trial.
- Males who were ultrasounded more likely to show signs of brain damage. Journal Epidemiology December 2001 .
- Ultrasounded babies more likely to develop epilepsy and learning difficulties. Ultrasound Abstracts .
- Males babies exposed to two or more ultrasounds were 32% more likely to be lefthanded (which is thought to be caused by brain damage). Ultrasound Abstracts .
- Four hours after ultrasound, cell death doubles and rate of cell division drops by 22% in mammals and researchers believe results same in humans. Ultrasound Abstracts .
- Risk of miscarriage significantly increased among women who perform ultrasound more than 20 hours a week. (Taskinen et al., 1990); Midwifery Today .
- Babies who had serious problems and were ultrasounded died more often than non-ultrasounded babies with serious problems. Midwifery Today
- Ultrasounded babies who were growth retarded were three times more likely more likely to be admitted to ICU than non-ultrasounded babies who were growth restricted. Midwifery Today
- Preterm labor more than doubled in ultrasounded women. (Lorenz et al., 1990); Midwifery Today
- Researchers who developed ultrasound admitted possibility of hazard from ultrasound and said that it should never, ever be used on babies under three months. Midwifery Today
- Cells exposed to single dose of ultrasound behave abnormally ten generations after insonation. Midwifery Today
- Ultrasound affects fetal weight, organ weight, immune systems, and blood platelets which allow blood to clot; researches believe problems from ultrasound - including possibility of cancer, leukemia, and congenital malformations - could take as long as 20 years to surface. Ultrasound Abstracts ; Effects of Frequent Ultrasound During Pregnancy: A Randomized Controlled Trial .
- Impaired brain function and decreased locomotor and exploratory activity in mice exposed to ultrasound. Effect of Fetal Exposure to Ultrasound on the Behavior of the Adult Mouse.
- Ultrasound's gaseous cavitation increases free radical production in amniotic fluid and blood plasma, and provides a likely mechanism for DNA damage. Crum et al (1987); Ellisman et al (1987)
- Because babies' heads are bowl shaped, radiation from ultrasound is magnified and can result in parts of the brain being subjected to extra high intensities of radiation. A Prudent Approach to Ultrasound Imaging of the Fetus and Newborn by Kenneth Taylor, M.D.
- Even if the above stats don't give you pause, how about the fact that ultrasound measures 100 decibels in utero - that's the equivalent of having your infant stand on a subway platform as a train comes roaring in and screeches to a halt - for the 20 or 30 or 60 minutes it takes for your doctor to do your ultrasound!!! New Scientist . As one writer notes, if you've ever heard of on opera singer breaking a sheet of glass with her voice, that is an example of what just one slow sound wave can do . . . but ultrasound uses ultra high frequency sound waves which bombard the child at an extremely high rate of speed. New Scientist.
Perhaps most ironic and compelling is this quote from one
of Yale's MD elite (Dr. Kenneth Taylor, M.D., Professor of
Diagnostic Radiology and Chief of the Ultrasound Section
at Yale University School of Medicine) who states: "I
would not let anybody get near my infant's head with a transducer
[ultrasound wand] . . ." A
Prudent Approach to Ultrasound Imaging of the Fetus and Newborn
by Kenneth Taylor, M.D.
Additional Articles From Mothering Magazine:
Ultrasound,
Denisce DiIanni, 24:27
Ultrasound: More Harm than Good?, Marsden Wagner, 77:50
Ultrasound Hits Bubbles (GN), 45:81
Mothering article reprints are $3.00 each. You may order a copy with your credit
card by calling 505-984-6292 or by fax 505-986-8335. If you prefer, you may
submit your request in writing accompanied by your payment to: Mothering, P.O.
Box 1690, Santa Fe, NM 87504.
Finally: therapeutic ultrasound has its risks
as well:
- Taskinen: A significant increased risk of spontaneous abortion amongst physiotherapists who use ultrasound for at least 20 hours a week and deep heat therapies for more than 5 hours a week.