Informed Choices: Ultrasounds in Pregnancy

Let’s talk about one of the more exciting diagnostics of pregnancy – the ultrasound.

Now, I have previously done a post on the different ultrasounds in pregnancy and when you can expect to have them if you are considered low riskyou can find that post here. Please review this if you are unfamiliar with pregnancy ultrasounds, but keep in mind that pregnancies that are considered high risk will have totally different ultrasound “schedules”. Please discuss any questions or concerns directly with your provider.

Disclaimer: this is not medical advice. This blog is for informational purposes only. Please seek guidance on your health from your trusted care provider.

What is the purpose of pregnancy ultrasounds?

Fetal ultrasound is really an amazing tool that we did not always have access to. It allows your provider to see your baby using sound waves. This way, your provider can see how baby is developing and monitor things like growth. Additionally, we use ultrasound to look for markers of any concerns related to growth, development, and well being. As a note – it is far from a perfect tool.

We may also use ultrasound to confirm a pregnancy or estimated date of delivery when this is harder to pinpoint (the “dating” ultrasound). Ultrasound may also be used in conjunction with a testing modality such as amniocentesis, or if there are signs of any complications.

Ultrasound is done abdominally or earlier on in pregnancy (or for specific imaging, like a neurosonogram) transvaginally.

A doppler is also considered a form of ultrasound (which is the tool used to listen to baby’s heartbeat at your appointments).

Your ultrasound is likely to be in 2D but some clinics have 3D or even 4D capabilities (including boutiques, which I will talk about again later but have also written about here).

Again, I refer you back to this post which has a more detailed description of the two main ultrasounds offered in pregnancy – the Nuchal Translucency ultrasound (NT scan) and the Anatomy scan and what they are looking at.

Are there risks?

As with pretty much anything in life, there are always risks. Even something that can be considered super benign and low-risk can be mentally risky, for example.

Overall – ultrasound is considered a safe diagnostic tool. It is notably safer in pregnancy than X-rays, since it does not use radiation.

As I mentioned, it is not perfect. This alone poses some risk in that it may not be able to detect every issue, or on the other side of things it may falsely detect a problem that is not there (you can read about my journey with false positives on ultrasound in my pregnancy journal posts starting here). Both of these can cause worry or concern – trust me; as well as potentially unnecessary testing, procedures and follow up.

Notably, ultrasound is considered the most safe when performed by professionals (as in – at a clinic you were sent to by your care provider, and not a boutique). The risk of attending boutiques is that the person performing the scan may not be a professional, and as a result they may give you false or misleading information. Again, please refer back to this post where I spoke about this more and my experience doing a boutique scan in my first pregnancy.

I often see women concerned about the potential effects and risks of sound waves to the baby. This is a legitimate concern, as thermal effects can occur – for example, we know other forms of heat can be harmful to baby in pregnancy as well. The temperature has to be quite high and thermal effects pose the most risk very early on in pregnancy (around 10 to 12 weeks). Non-thermal harm is less of a concern in obstetrical ultrasounds.

Notably, doppler ultrasounds may also have risks, specifically pulsed (or spectral) dopplers, with animal studies showing 5-min interval exposure impairing memory. This again, occurred early on in gestation, so the recommendation is to avoid this type of doppler specifically early on.

Ultrasound has been used for many years now without known harm to humans or their babies. Considerations that are recommended are avoiding use of pulsed/spectral dopplers in first trimester and monitoring time of exposure in all ultrasounds. If you have concerns about ultrasounds, speak to your care provider.

What are the main benefits?

Ultrasound has a very important role to play in pregnancy, despite the risks of false positives, because it can help to detect growth and development issues much earlier than was possible before its use. Some congenital anomalies, in particular, can be detected in pregnancy by ultrasound, often in conjunction with blood testing like the eFTS, NIPT or diagnostic tests like amniocentesis. This means that various actions can be taken to decrease risks for the baby, mom, delivery, and so on. The actions vary – and are not always easy decisions – but ultrasound does allow us to have options, where we previously might not have. Detection of anomalies is sort of a contested point as a benefit – some may see it as a benefit, and others may not. Have discussions with your healthcare provider if you have questions or concerns.

Other benefits that are supported by current evidence include more accurate dating for the pregnancy; ability to identify location of ectopic pregnancies; determination of viability; can detect twins (or more) earlier on; and placental monitoring.

Some of the literature also shows ultrasounds can impact the mother-child bond in a positive way. It certainly is often an (sometimes) anxiety-provoking yet exciting moment for new parents.

My Experience

Ultrasound is low risk when done by a medical professional as per the American College of Obstetricians and Gynecologists (ACOG). I never hesitated to pursue a routine ultrasound because the thermal risk is low, and I trust my medical professionals and care providers with their recommendations.

In my first pregnancy and early in my second, an ultrasound did cause me some anxiety – but I am also an anxious person, and I sometimes feel I “know too much” as a nurse. We see things day in and day out and they can be hard to forget when you’re going that same test or exam yourself. On the other hand, they also brought so much joy – to see the little life inside!

I will admit my second pregnancy, with the increased number of ultrasounds, became a bit exhausting. It went from joy to seeing my baby to fear that “something else” might go wrong. I was very happy that my last scan had such a positive note to it. It was suggested by the MFMs I saw in Toronto to pursue a growth scan, and I am aware of the recommendation – but because of the honest trauma I experienced with ultrasounds this pregnancy, I have decided to keep it on the back burner for now and only pursue it if it is recommended again. I wrote more about this in my second most recent pregnancy journal update here, if you’d like to see more about my decision-making. I’m 34 weeks so if concerns arise from myself (more so anxiety) or my midwives, we will do the growth scan – but I had a long discussion and weighed my pros and cons on the subject (with the help of the Evidence Based Birth article I linked in the other post) and made my decision for now. That is informed decision making.

When it comes to routine ultrasounds – I think the benefits certainly outweigh the risks. But I know that everyone’s situation can be different – you may have had bad experiences (worse than mine which was rather benign but still honestly scarring) with ultrasounds and feel fear, discomfort or distrust of them – and that is something that warrants a discussion with your provider. See if there are ways you can be supported in your ultrasound so that it feels less daunting. Never be afraid to have discussions, ask questions and voice your honest concerns.

So there you have it – a little more on ultrasounds. I want to provide a short list of additional resources I have found as well from reliable resources, you can find that just below. Thanks for reading and stay tuned for my next Informed Choices post coming soon!

Additional Resources:

ACOG’s Ultrasound Exam FAQ Page

Routine Ultrasounds – Society of Obstetricians and Gynaecologists of Canada

A Brief History of Ultrasound in Medicine

Info on What Is Being Examined in a Second Trimester Ultrasound


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