A conversation I had last week brought this topic to mind. This was with a non-medical person who works with pregnant women. I found I needed to explain to her what “valid medical reason” meant, with regard to ultrasound during pregnancy. It also brought me to tell her of the risks of ultrasound to the fetus. So, I’m going to talk about both of these things.
Valid Medical Reasons:
- Genetic history of birth defects, which can be detected visually
- If you’ve had previous uterine surgery, resulting in scarring, ultrasound is used to determine placental location and possible placenta accreta.
- Can also be used to determine placenta previa.
- Suspected problem with the baby
- Restricted growth
- Preterm labor – as indicated by leaking amniotic fluid or bleeding
- Post dates scan to determine the health of the placenta
According to the World Health Organization and U.S. Department of Health and Human Services report, “It is not clear at this time whether ultrasound fetal monitoring is beneficial to the mother or fetus in terms of pregnancy outcome…If there is no generally acknowledged benefit to the monitoring, there is no reason to expose patients to increased cost and risk. The question of benefit has not yet been resolved…and the potential for delayed effects has been virtually ignored.”
Non-Valid “Medical” Reasons:
- Confirm the sex of the baby.
- Well, that’s nice and all, but it’s not for a medical reason. It’s so you can decorate the nursery or buy clothes in pink or blue.
- Assess gestational age (how many weeks pregnant are you)
- This can be helpful to know, but can also be determined by other means. Measuring the fundal height (top of the uterus) will tell you approximately how many weeks along you are, as well as using the date of your last menstrual period.
- Assess fetal size and growth
- This is only accurate till 20 weeks of pregnancy. After that the accuracy rate drops exponentially each week. By 38 weeks, the ultrasound is +/- 1.5 lbs in either direction for baby’s weight. If there is a suspected (or confirmed issues with the baby, then additional ultrasounds may be required)
- Confirm multiple pregnancy
- With a good hands-on practitioner, they can tell if you’ve got multiples in there… by feeling your belly.
- Determine Fetal Presentation (position of the baby)
- By palpating your belly, your care provider can tell fetal position. During labor, with a vaginal exam, they can feel the sagital sutures (soft spots) on the baby’s head and determine the presentation.
- 3D/4D ultrasound
- There is zero medical reason for this. This is for making money, so yo get a “really good picture” of baby.
So, what is ultrasound? It is a sound wave between 2 – 18 MHz. This is beyond the range of human hearing. It produces a vibration; the machine reads the echo of the vibration to determine depth and creates an image. Sound is a vibration, vibrations produce heat. It is well documented that a fetus will “hide” from the ultrasound. This is because; it is believed they can feel the heat and vibration of the machine.
From our friends at Wikipedia: https://en.wikipedia.org/wiki/Medical_ultrasonography
“Risks and side-effects
Ultrasonography is generally considered a “safe” imaging modality.[15] However slight detrimental effects have been occasionally observed (see below). Diagnostic ultrasound studies of the foetus are generally considered to be safe during pregnancy. This diagnostic procedure should be performed only when there is a valid medical indication, and the lowest possible ultrasonic exposure setting should be used to gain the necessary diagnostic information under the “as low as reasonably achievable” or ALARA principle.
World Health Organizations technical report series 875(1998).[16] supports that ultrasound is harmless: “Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion”. Although there is no evidence ultrasound could be harmful for the foetus, US Food and Drug Administration views promotion, selling, or leasing of ultrasound equipment for making “keepsake foetal videos” to be an unapproved use of a medical device.
Studies on the safety of ultrasound
- A study at the Yale School of Medicine found a correlation between prolonged and frequent use of ultrasound and abnormal neuronal migration in mice.[17] A meta-analysis of several ultrasonography studies found no statistically significant harmful effects from ultrasonography, but mentioned that there was a lack of data on long-term substantive outcomes such as neurodevelopment.[18]”
The Study – https://www.pnas.org/content/103/34/12903.full
Also on Wikipedia https://en.wikipedia.org/wiki/Obstetrical_ultrasonography
The concerns with ultrasounds on a developing fetus are the following:
- Restricted growth
- Speech delays
- Fine motor skill delays
- Impaired brain function
- Autism
From Midwifery Today https://www.midwiferytoday.com/articles/ultrasoundrodgers.asp
“The idea that a prenatal ultrasound can be hazardous is not new. The previously mentioned 1982 WHO report, in its summary “Effects of Ultrasound on Biological Systems,” stated that “…animal studies suggest that neurological, behavioral, developmental, immunological, haematological changes and reduced fetal weight can result from exposure to ultrasound.””
Another listing of studies, with links – https://www.ob-ultrasound.net/joewoo3x.html
The other big risk is misdiagnosis and misinterpretation of the ultrasound results by the technician or the doctor. This is everything from getting the baby’s gender wrong, to seeing an issue with the spine or heart, that isn’t there (or missing one that is). This can be due to “fuzzy images”, an active baby, an obese mom, anterior placenta, just to name a few.
So, if there is potential for harm, what is the good of it? Why use it at all? How much is too much?
If your OB is scanning your belly at every visit, it’s too much. Much past your 20 week “big” scan is too much. If there is a genetic concern, or something was found to be a problem, then the ultrasound can be helpful in determining the degree of the problem, and possible solutions.
Although there is a lot of information about the risks, and potential harm of ultrasounds, many of the studies are small, or not focused enough to provide good scientific evidence to strongly caution parents against the use of ultrasound. The evidence, although gathered over a long period of time, is, at this point anecdotal.
Please do ask your doctor or midwife about the necessity of the ultrasound before consenting. Ask yourself the question – why do I need to know the information the ultrasound will give me. Is it more beneficial to know, or not to know? How does this help me? How does this help baby? Do the benefits outweigh the risks? If you make an informed choice, you can feel confident you did the right thing.
***Personally, I’m not dramatically opposed to ultrasounds. I had 2 with Owen, and 1 with Elaine. I do, however, think in many cases they are overused, with little or no benefit to mom and baby. With the strongest risk being misinterpretation of results, I caution against the efficacy of the ultrasound.
Nancy says
I do, however, think that figuring out a due date is a valid medical reason for an ultrasound. I would hate to have to send a woman to the hospital and use monitoring because I think she’s 36 weeks and have her really be full term, and more relevant to all the women who go to doctors, a lot of babies are induced because the doctor thinks they are 41 weeks when they are really not. There is good research that when you do more ultrasounds for checking dates you avoid A LOT of unnecessary inductions.
This is from Nancy, a Midwife Emeritus from the Midwife Center.