Are ultrasounds dangerous to a fetus?

Factual Questions
1

When ultrasounds are performed on a pregnant woman, can the sonic radiation be damaging to the fetus? Someone mentioned that they can damage hearing (I know the frequencies are out of hearing range, but wondered if they could affect the developing aural organs).

I looked briefly on the 'net and found a minimum of studies regarding this and they all appeared to address low-risk births. Any studies tended to point to premature birth and a low birthweight more than anything else. The final score seemed to be: ‘Can’t tell, don’t bother because they don’t really help’.

As we are expecting twins, I am a little concerned about excessive scans. Twins are considered a high(er)-risk birth and the OB will probably want to monitor the progress a little more closely. Typically women have 1-3 during their pregnancy and we could expect as many as 10.

2

FWIW, the sonic frequencies used in ultrasound are so much higher than the audible range (hundreds to thousands of times higher), that the aural organs shouldn’t be any more sensitive than any other developing organ.

That said, I’ve never seen many studies about it, but it’s widely believed to be harmless.

Note- I’m not a doctor, or even well-versed on medical topics. As a EE, my area of interested is the electronics in the equipment :slight_smile:

Arjuna34

3

First, congrats on the twins!

I too briefly wondered about this when my wife was pregnant. But in all my readings, I did not come across any risks of ultrasounds. I’d be interested in any good links on the subject.

Bottom line is…ultrasounds are seem to be an excellent method to check the health & progress of the fetus. It’s probably riskier to not get the ultrasound because you would not be aware of any problems until it’s potentially too late.

4

A section on “Antenatal care in low risk pregnancies” by Bricker, Crowley, Neilson, and O’Dowd is included in the third edition of Clinical Evidence published by the BMJ Publishing Group. They have systematically assessed all the evidence for benefit and harm from preconception care, postconception care, and routine ultrasound screening. I can’t summarize all 17 pages but basically, various studies of ultrasound suggested various effects (e.g., fewer right handed children than expected among those exposed; more children < 10th percentile for birthweight among those exposed, etc.) but no adverse effect has been found consistently suggesting that the associations that have been found in individual studies were due to chance and that there are no adverse effects (although extremely rare [i.e., 1 in 10,000,000] effects are virtually impossible to detect and therefor impossible to rule out).

If you go to http://www.evidence.org and register, you can read the full text of volume 4 of Clinical Evidence.

5

I ddi a search on Google with “ultrasound fetus hazard” and received a number of hits which were off target, and a few that suggested caution and limited exposure at a midwifery site by the author of “Ultrasound? Unsound”. She made references to many studies, but to me seemed inconclusive due to the lack of details in the statistics.

Swiss albino Mice study

Arjuna34 - I know the ultrasound frequencies are out of hearing range, but superlow frequencies are as well and (UL?) have been experimented with by the military and can turn guts to goo. I’m wondering if the ultrahigh frequencies could have a deleterious effect on the gestational development. Weren’t they working on a sonic wand for liposuction to turn fat to liquid to make for an easier ‘cleanup’? heh heh heh…I just had visions of Martian exploding heads from Mars Attacks!

In some of the sites, it was suggested that experimentation and safety testing was limited before it gained acceptance in the late 70s/early 80s.

6

I had no u/s with my first pregnancy because it was a low risk pregnancy. He was stillborn but even with u/s he still would have been stillborn. I had u/s with my next three pregnancies but I never felt they were going to be a guarantee of a perfect outcome. They were useful for monitoring growth and development and for reassurance.

IMO the absolute safety of u/s has not been conclusively demonstrated and equally a clear danger has not been conclusively demonstrated. I don’t think that regular routine u/s on every pregnant woman is needed but in higher risk pregnancies, u/s is a safe enough technology that the putative risks outweigh the benefits.

U/S is a fairly expensive technology to use with every pregnancy and given that no-one has demonstrated better outcomes with the increased use of the technology, I think the use should be limited to those pregnancies where it might make a difference.

Good luck with your twins :). I chose in later pregnancies to use u/s. One midwife did dismiss me as a client because I chose to have one when I was worried I was miscarrying again. I thought that was an excessive reaction and extremely bad practice.

7

Is ultrasound expensive technology? I would have thought not.

My OB/GYN uses US as a diagnostic tool, and it is very helpful for tracking fetal growth & development. Hadn’t ever heard about possible dangers from it, asked my best friend who is a RN and neither had she.

Besides, how else would I get the cute little “alien” picture for my desk? My doctor even allowed us to bring a videotape and get a copy of the ultrasounds- very cool. Many doctors won’t because of fear of lawsuits.

8

It works out to be expensive technology when it is done unnecessarily without improvement in outcomes. If insurance companies are paying out for unnecessary procedures, it becomes expensive. If routine U/S was responsible for an improvement in outcomes overall, then I wouldn’t consider it expensive but no studies have shown that routine U/S monitoring improves outcome overall.

I don’t know if your ob/gyn was charging for each and every U/S but I do know that in NZ there was a huge blowout in the maternity services budget that was brought back under control by requiring hcps to justify U/S on medical grounds. Each woman got one U/S early in pregnancy but repeat U/S was only payable if medically justified.

9

If you consider that ultrasound has been used extensively in the US for over 20 years, it seems pretty safe. I think that if there were going to be major problems, they would be well documented by now. FTR I had one with my daughter and none with my son.

10

Primaflora, you took the words right out of my mouth.

dragonlady, you’re probably right, but I think it would ne hard to know. It’s the high-risk pregnancies that get the multiple ultrasounds. If they have a cumulative damaging effect, I suspect the ultrasound would be the last thing to be suspected as the culprit. After all, the babies were already gestated in high-risk conditions. Problems would probably be attributed to those factors (high blood pressure, multiple fetuses, low amniotic fluid, maternal age, whatever caused the high-risk designation in the first place).

cantara, I wouldn’t worry. There’s enough a question about US that I don’t think healthy moms with low-risk pregnancies should imprudently subject themselves to multiple unnecessary ultrasounds, but in a higer-risk pregnancy ultrasounds (multiple ones) are too useful to forgo. I’m speaking as a layman who probed this issue a little bit during my own pregnancy.

11

Primaflora wrote:

Demonstrating the absolute safety of anything is fundamentally impossible. There isn’t any mechanism we know of for it to hurt the fetus, lab tests don’t seem to affect tissue growth, and the epidemiology doesn’t reveal any higher risks, so it’s implausible that there are any. But it’s impossible to say there are none.

Just like with mobile phone radiation - there is no plausible mechanism for it to cause damage, and no correlations with disease that are apparent. But some groups want them to be proven safe or banned.

The best you can do is to say that the risk is below some low threshold (though it may be non-zero), and balance that amount of risk with the benefits.

12

I’m not convinced that there is any correlation between the U/S and any sorts of problems. Statistics are very useful for proving a point depending on what you want to prove. That appears to be the case here. I believe we’ll go ahead with the U/S to ensure that we are doing everything we can (nutrition, activity, etc) for the health of the babies. We’re just 18 weeks along now…

We are also going to be doing an “unnecessary” U/S in the next couple of weeks. An old college chum is working with U/S technology to render 3D images from traditional U/S scans and we’ve ‘volunteered’ to help out with the project. All the same, I’m hoping that this will also be a traditional obstetric exam at the same time.

13

I’ve seen images of the 3d ultrasound. It had a limited trial phase here. The images are spooky, but very cool. :slight_smile:

14

I believe the AMA issued a statement saying that non-medically-necessary ultrasounds were a mis-use of the technology. And IIRC they cost about $300 for each use (three + years ago), according to my insurance billing.

I had three - one to check for anatomy abnormalities, one when I discovered that I might have a genetic disorder, and one when my son was getting very overdue and they wanted to do a ‘biophysical profile’ to check his condition, the placental condition, amount of fluid, (etc), before deciding whether to induce, and when. I had decided to do as few as reasonable, but would do whatever seemed a functional use of the technology. I also skipped doppler ultrasound (the dopotone heart-beat monitor) once our son was big enough to get picked up with a fetoscope. Doppler is a more powerful pulse than the visual ultrasound, and if there’s an issue with one, there’s probably an issue with the other. But think about it - most people these days are using the dopotone, so while it is for a shorter time, how many times does the doctor listen to the heartbeat? And the fetal monitor during labor - same technology. I think most of the concern was generated by what was seen to be frivolous use of the technology.

From what I read in the most-well-thought-out opinion I found (which I can’t currently locate, sorry), while there might be some impact from US, it is on the order of ‘excessive (5+) ultrasounds possibly contibuting to poor uterine conditions’ - which then can result in low birthweight, late speech development, and other things, if there are enough contributors, in the right order, at the right (or wrong) developmental times. But there’s insufficient info to tell what those times are, let alone what all the other factors are. It usually takes more than one thing to cause such conditions, and if by using the ultrasound more often (in a case where it might help), you then catch and/or manage to control one of the more critical issues, then you still end up ahead. Oxygenation is probably the most critical issue for most of development, followed by nutrition. So if by using ultrasound you can keep track of something like placental function (therefore oxygenation and nutrition) in a situation that is already non-ideal uterine conditions (multiples), you are using the tool properly. If you are already doing multiple ultrasounds, I would think the margin of difference for one more (the 3D stuff) would be small, and you are then contributing to developing a technology that might help others immensely.

If there is no medical reason to use US often or repeatedly, then don’t - no point adding a possible contributing factor if it won’t reduce another factor, not to mention the cost of healthcare issue. As Primaflora said, do a cost/benefit analysis.

BTW, ‘Reassurance’ is also a valid reason for US, as maternal stress is considered a factor in ‘poor uterine conditions’.

15

WARNING: The following is a speculation-free post.

Many of the questions about the harms and benefits of prenatal practices, including some uses of ultrasound, were addressed by Bricker, Crowley, Neilson, and O’Dowd (see citation in my previous post). Based on their assessment of the evidence, they sorted the interventions they studied into the following categories.

Likely to be beneficial
-Preconception screening and immunisation for rubella
-Preconception prescription of folic acid supplements
-Community versus hospital based care in low risk women
-Antenatal advice on smoking cessation
-Antenatal classes
-Routine ultrasound before 24 weeks’ gestation (to determine duration of pregnancy, multiple pregnancies)
-Routine ultrasound in the second trimester to detect fetal abnormalities

Unknown effectiveness
-Preconception advice on lifestyle change
-First trimester nuchal tranlucency screening
-Routine first trimester ultrasound to detect fetal abnormalities

Unlikely to be beneficial
-Advising women to eat a high folate diet before conception
-Reducing the frequency of antenatal visits (clinical outcomes unaltered, satisfaction reduced)
-Routine ultrasound screening in late pregnancy (after 24 weeks gestation)

Likely to be ineffective or harmful
-Weighing at antenatal visits
-Routine Doppler ultrasound of the umbilical and/or uterine artery

I don’t know how many of the authors have ever been pregnant or whether they scanned the internet searching on “ultrasound” or not. I do know they searched exhaustively and systematically (emphasis on exhaustively and systematically) for evidence of benefits and harms and that they then weighed the evidence using explicit criteria (that did not give quality points for cute titles). These are people who make Cecil look like he’s talking off the top of his head.

16

I realize this is off-topic, but these seem to be an odd combination. Why are supplements beneficial when eating a “naturally” high folate diet is not?

17

WAG until Yeah responds:
They didn’t say “eating a high-folate diet” was unlikely to help, they said “advising women to eat a high folate diet”. Maybe women aren’t as likely to stick to a special diet as they are to take a pill?

BTW, excellent posts, Yeah! I’ve bookmarked the evident.org link you posted :slight_smile:

Arjuna34

18

Arjuna34 is correct. The Clinical Evidence people look at evidence, not theory. You will have to look at the original article yourself to see a summary of the evidence (my free trial has expired), but IIRC, there are at least two, large, well done, randomized, controlled trials showing that prescribing folic acid supplements to women planning to become pregnant reduces neural tube defects in their offspring and causes no significant harm compared with not prescribing folate supplements. The word “likely” means that the evidence is pretty good but maybe not completely conclusive (what is?). I don’t know about the studies of advising women to eat a high folate diet before conception but the use of the word “unlikely” probably means that there are some pretty good studies that showed no benefit but as Arjuna34 points out, they were looking at the benefits and harms of advising women to eat a high folate diet, not at the benefits of women eating high folate diets. (You have to remember, Clinical Evidence is intended to help clinicians better serve their patients and what a clinician needs to know is not just whether preconception folate prevents neural tube defects but what she can do to prevent neural tube defects in her patients. Based on the Clinical Evidence assessment of the data, clinicians are likely to benefit their patients if they prescribe folate supplements. They are not likely to benefit their patients if they just advise a high folate diet.)

Getting back to the OP, the same procedure used for looking at evidence of the benefits and harms of prescribing folate supplements and advising women to eat a high folate diet were used for evaluating the evidence for benefits and harms of using ultrasound for certain purposes during pregnancy.

19

for a very lucid and informative series of posts.

I initially posted this after hearing from FOAF about possible negative repurcusions from u/s use. I would say that from my (limited) research, and the points and cites posted here we feel much more comfortable with the procedures.

[probably needs a new post]
Regarding the folic acid, my wife started taking a supplement after we discovered we were pregnant at about 8/9 weeks. Then I read that the benefits of the folic acid are realized very early on in the pregnancy, and so we missed the window of opportunity. She continued taking it for a few weeks anyway, but has since stopped taking it.
[/probably needs a new post]

20

Re: folic acid, a few months ago Medscape reported that the baseline folate level for American women had risen dramatically after it was added to flour as a standard fortification. So overall, if you are in the US, chances are way better that she didn’t need it as much as she might have a year ago. I hope that eases your mind a bit, if you were stressing about missing that window.