So really, how dangerous are ultrasounds?

September 9, 2009 8:16 PM

So really, how dangerous are ultrasounds? I'm 17 weeks pregnant, have had one visual ultrasound and one brief use of doppler at an exam, and was planning another ultrasound around 18-20 weeks. Recently, though, I read some studies about the dangers of ultrasounds, particularly when there's no unusual medical need. Critics of the practice cite these studies, while those on the other side of the debate seem to say that there are no studies. I'm not a scientist. Has anyone reviewed or rebutted these studies for a general audience?
posted by lgyre to health & fitness (19 comments total)

http://www.ncbi.nlm.nih.gov/pubmed/19291813

This study is a meta-analysis which means that it summarizes the different epidemiological studies that were done on the topic that you're concerned about.
posted by scalespace at 8:56 PM on September 9

Wait what? People are concerned about ultrasounds now? Good lord there are about a billion things to worry about already when you're pregnant. IANAS but I would venture to guess that the benefit of ultrasounds, in so much as they can detect any number of abnormalities that can then be dealt with, would vastly outweigh any risks.
posted by otherwordlyglow at 9:04 PM on September 9 [2 favorites has favorites]

Presumably you're referring to ultrasounds performed by professionally trained technicians affiliated with licensed medical providers, right? Go forth and be imaged.
posted by otherwordlyglow at 9:05 PM on September 9 [1 favorite has favorites]

It's been a while since I concerned myself about this but my conclusions (and I am certainly no epidemiologist, though I did study and work in the field of science) is that there is a medical consensus that ultrasound as it is conventionally used in prenatal care is safe. This is not a wholly uniform opinion; one of the few legitimate publications I came across in my own research that brought up the question was this (only an abstract available online) which indicates that while the majority of studies support the safety of ultrasound, there are some that raise the possibility of developmental effects.

Note that this paper basically concludes only that there should be more research that collects more relevant data about the specifics of exposure and controls for "confounding" variables (basically this means weeding out issues that might be real or contributing causes that are connected to the supposed cause in an unrealized way - this is a big problem with epidemiological research, where you look at the incidence of conditions in a population and search for common qualities that might be causes of the conditions - to provide a stupid made-up example, imagine a study that finds that a higher percentage of people who carry matches in their pockets get lung cancer and concludes carrying matches causes cancer - in fact smoking causes both the cancer and the tendency to carry matches). That study does not suggest that there are in fact valid concerns about ultrasound, just that there's enough questionable data to justify looking at it more carefully.

Another issue is the technology is rapidly evolving and there is a question of whether it is being monitored and regulated enough. This is probably not relevant to you.

Another objection I saw a lot to ultrasound basically ran along the lines that it's not a great diagnostic tool and women end up having more dangerous and invasive tests like amniocentesis or CVS which have definite, undenied and more serious risks (really nobody legitimate is arguing ultrasound could kill your baby, citing my first link again, the effects they're discussing are developmental issues that while nothing you'd want to see are not anywhere near life-threatening or birth-defect causing or anything like that).

I never found any legitimate science addressing this question. I think it's a pretty questionable argument: if an ultrasound is not a sufficient justification for having a particular test done the issue lies with how the decision is made to have that test, not with ultrasound per se. And of course it ignores the converse, the possibility of not having the secondary test because of not having an ultrasound when in fact the test is necessary or desirable.

Bottom line, I do not think there is definitive science that ultrasound is without risks but that kind of thing can be hard to come by. Ultrasound has been around for a long time now and it is very prevalent and there is a lot of evidence that it is safe. It probably is worthwhile to study it more and the technology needs to be tracked and reviewed as it develops. After looking at a lot of stuff I personally didn't worry about it in the slightest when my wife was pregnant.
posted by nanojath at 9:08 PM on September 9 [5 favorites has favorites]

From the link that ScaleSpace posted:

CONCLUSION: According to the available evidence, exposure to diagnostic ultrasonography during pregnancy appears to be safe.

posted by Chocolate Pickle at 9:09 PM on September 9

I guess I'll add further another conclusion I came to with respect to my son's birth, which is that the internet is generally a terrible place to conduct research about health and medicine. There were very very serious medical complications attendant to the birth of my son so believe me, I say this as a complete hypocrite but also one who knows whereof he speaks: the internet will scare you more than it informs you and it will never be a better source of information than your medical professionals. Never. Ease up on the online pregnancy research, if you're getting proper prenatal care you are getting all the medical information you need about your pregnancy.
posted by nanojath at 9:24 PM on September 9 [4 favorites has favorites]

I have a friend who believes that her child's developmental delays are linked to the multiple ultrasounds she had early on in her pregnancy. She says the research bears out a link to the week or two where she had multiple ultrasounds and the change in the baby's makeup. It had to do with some sort of tiny bubbles created in the brain by the ultrasound. She apparently did a lot of research around this. However, I have never otherwise heard of such a thing and suspect that, if I did the research, I might not come to the same conclusion.
posted by acoutu at 9:42 PM on September 9

I had a ton of ultrasounds (twin pregnancy) and perfectly healthy babies. Try not to psych yourself out too much.
posted by gnat at 9:48 PM on September 9

Acoutu, your friend is falling for that most classic of fallacies, Post Hoc Ergo Propter Hoc.

And that most classic of misconceptions: that bad things don't just happen for no discernible reason. Unfortunately, a lot of bad things do happen just on their own without being caused by modern technology.

I have a friend who thinks that Dihydrogen Monoxide is one of the greatest threats facing mankind today.

You can't trust everything you read on the net.
posted by Chocolate Pickle at 10:35 PM on September 9 [1 favorite has favorites]

By the way, Wikipedia on DHMO.

Look, ultrasound is safe. But there isn't a product of modern technology that you can't find someone who will claim it causes cancer or birth defects or autism.
posted by Chocolate Pickle at 10:38 PM on September 9

Wait what? People are concerned about ultrasounds now? Good lord there are about a billion things to worry about already when you're pregnant. IANAS but I would venture to guess that the benefit of ultrasounds, in so much as they can detect any number of abnormalities that can then be dealt with, would vastly outweigh any risks.

At the risk of a slight derail: people are not concerned about ultrasounds per se, but the popularity of ultrasounds for in utero videos and even home ultrasound kits to "take a peak" whenever they like.
posted by rodgerd at 12:02 AM on September 10

In both Sweden and Denmark, countries that are pretty picky at only doing things safe, all pregnancies have two or three ultrasounds at different stages of pregnancy. I had three, at week 15 (we miscalculated and were there too early to see what was needed) at week 17 and another one at a later date (week 25?). My healthy child id now 3 and has a perfectly healthy brain makeup (if you ask me, I'll tell you she's the smartest girl ever too).

This is not a scientific answer, but from someone who also worried at the time moderation is key. Don't do more than three if it worries you, nobody needs to check in on the baby that often.
posted by dabitch at 12:57 AM on September 10 [1 favorite has favorites]

This is merely anecdotal evidence, but:

Every single person I've ever known that has had a baby has had ultrasounds.

Almost every single person I've ever known that has had a baby has had a healthy, happy pregnancy, birth, and child-rearing; and the ones that didn't could point to causes besides ultrasound.

Yes, it's personal-life science, but valid up to a point nonetheless: I've seen people getting ultrasounds all my life, gotten them myself at least half a dozen times, and never once have I seen or heard of someone experiencing ill effects.
posted by koeselitz at 2:47 AM on September 10 [2 favorites has favorites]

More of the risk with ultrasounds, as nanojeth pointed out, has to do with whether they lead to something that may cause the doctor to suggest more tests, that cause the mother to agree to things she may not want, etc.

An early ultrasound for dating purposes is fine. An ultrasound around 17 - 21 weeks for looking for how things are developing and for any defects is fine. An ultrasound at 38 weeks that leads the care provider to tell the mom, "The baby is too big. Let's schedule a c-section." is not okay. Late ultrasounds, after 30 weeks, are off by a lot more on due dates than early ultrasounds and estimates of the baby's size can be off by as much as 3 lbs. or more. To me, therein lie the dangers of (late pregnancy) ultrasounds. So, unless there's a real medical need for an ultrasound after the second trimester (watching a possible defect, need for a external cephalic version to get a baby from breech to head down, etc.), I'd avoid any after.

You also have the keepsake ultrasound businesses that do "4-d" ultrasounds. These places aren't doing ultrasounds for medical purposes and may not have a licensed tech conducting the ultrasound. I suspect it's possible that these types of ultrasounds are less safe than the standard ones during pregnancy.

But as for the usual, run-of-the-mill, ultrasound-done-by-a-tech spoken of here, it's safe.
posted by zizzle at 6:52 AM on September 10

Ultrasounds use sound waves that are higher frequency than we can hear. We can read the resultant echoes as a picture. Apparently, the fetus can hear these sounds, and they are quite loud, but they can easily move to reduce the volume. Speaking non-expertly, I can't see why sound waves would be harmful. The fetus hears all sorts of other sounds just traveling around with mom. If Go Banana Jr. could endure beginner band classes, I'm sure a few ultrasounds are nothing to worry about.
posted by Go Banana at 7:30 AM on September 10

My dad was an ultrasound fellow the year my mom was pregnant with me. Hence, they took a lot of ultrasounds. I don't think they would have done this had it been unsafe. (i.e. my dad didn't also throw my mom in the CT scanner.)
posted by melodykramer at 7:31 AM on September 10

Apparently, the fetus can hear these sounds...

I don't know where you got that idea. Usually they use 5 MHz. Nothing alive can hear frequencies that high.
posted by Chocolate Pickle at 7:56 AM on September 10

Maybe they feel the sounds, Chocolate Pickle.

For various reasons I had about a dozen medical-office ultrasounds with one full term pregnancy and each was more difficult than the last, as child would freak the heck out and not hold still during the exam (we did test exams prodding and rolling in the same ways with the device off and child was not even a tiny percent as active). The child was quite sensitive to sounds until pre-tween years.

Final full-term pregnancy, fewer scans but no acrobatics or kicking at or rolling from the hand-held scanning device. The child is less sensitive to sounds than the sibling.
posted by tilde at 8:03 PM on September 11

Chocolate Pickle, if it wasn't clear, I suspect that my friend and I would also diverge on DHMO, with one of us knowing what it was without even reading the link.
posted by acoutu at 6:04 PM on September 12