Are Ultrasound (Sonography) Scans Safe During Pregnancy?

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Dr. Rima Sonpal(Gynecologist/Obstetrician)
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Are Ultrasound (Sonography) Scans Safe During Pregnancy?

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Antenatal ultrasound scans can be used for various reasons during pregnancy. An ultrasound scan can help detect complications or it can be used to evaluate the baby’s position and movements in the womb. But some couples have concerns about ultrasounds. While there is no conclusive evidence suggesting that ultrasound scans are harmful, healthcare experts discourage their use unless they conducted for medical reasons.

Are Ultrasound Scans Safe During Pregnancy?

Are Ultrasound Scans Safe During Pregnancy?

When an ultrasound scan is conducted by a trained professional, who follows the proper guidelines, the pregnant woman or her baby should not face any problem. The heat produced during the ultrasound scan is too little to cause any significant damage. Professionals also take measures to minimize heat build-up. Certain medical conditions may require a doctor to suggest frequent ultrasound scans, but you can stay assured as your ultrasound technician will conduct the scan with utmost care. There are contradictory opinions regarding the value of ultrasound scans during pregnancy. If you’re pregnant and have doubts about ultrasound scans, speak to your doctor. Voice your concerns to her, she will be able to guide you the best.

Can Ultrasound Scans Be Harmful to Your Baby?

Conducting ultrasound scans doesn’t harm a baby but there are certain doubts regarding the following:

  • The heat generated: Ultrasounds produce less than 1°celsius of heat. There is a medical theory that says that harm is caused only if the temperature of the scanned tissues increases by 4°C (for instance, from 36°C to 40°C).
  • Sound waves: The sound beams create a stream of fluid that possibly imparts a mechanical force at the surface of cells. This phenomenon is still not properly understood, but there is a concern about the adverse effects.
  • Intensity: The ultrasound intensity is low and spread over a large area. There have been reports of the rising intensity of machines used. Earlier, the intensity of commercially used ultrasound machines was not more than 94 mW/cm2. There have been a 7 times rise in intensity now, of up to 720 mW/cm2.
  • Cavitation: This is a condition that affects tissues with the formation of gas pockets after birth. This is still highly debated but there are suggestions that our tissues may contain microbubbles that can be affected by cavitation.

What If You Need Frequent Ultrasounds During Pregnancy?

The need for frequent ultrasound scans arises only in case of certain medical conditions. It is advised to undertake frequent ultrasounds only for specific medical reasons, otherwise, ultrasound scans should be kept to a minimum.

What About the Other Types of Ultrasound Scans?

There are many types of ultrasound with varying technologies that incorporate 3D and 4D imaging. But many couples are concerned about 3d and 4d ultrasound scans. Let’s find out about 2D, 3D, and 4D ultrasound scans.

2D ultrasound: 2D ultrasounds are the most common type of scans and are considered safe because of the following:

  • are of low intensity
  • spread over a large area
  • generate little heat
  • are spread out by the fluid that the baby floats in and its movements

3D and 4D ultrasounds: These create one complete picture from sections of 2D images and concentration of power is the same as in a 2D scan. Hence, they are also considered safe.

Doppler scans: These check whether the placenta is properly delivering oxygen and nutrients to the baby. Doppler is said to generate more heat because they focus sound beams over a small area. But to do that temperature is not raised to very high levels because:

  1. The tools used are not held in the same body area for long durations.
  2. The scan checks blood flow and the motion of blood dissipate the heat.
  3. Some scan machines can automatically reduce the power of the sound beam to minimize intensity.
  4. Handheld Dopplers and cardiotocographs (CTGs), used to hear the baby’s heartbeat, are also low in intensity.

How Will the Doctor Control the Heat From a Scan?

As mentioned before, a scan usually takes not more than thirty minutes and the doctor conducting it keeps moving the tool over the tummy to minimize heat build-up. Some suggest this also makes frequent ultrasounds safe in cases where there is a medical necessity for them.

How Can You Ensure That Your Ultrasound Scan is Performed Safely?

Here is some advice from experts that will help dispel your fear.

  • Make sure you go for this scan only for medical reasons.
  • Make sure the probe is not held over your tummy for a long time.
  • Ensure that the operator is subjecting you to a minimum total exposure time, that is 30 minutes for a normal ultrasound.
  • If possible, check on the scanning intensities of the machines.

When Does a Doctor Advice to Perform Scans Multiple Times?

Your doctor may suggest frequent ultrasound scans in the following cases:

  • If you’re carrying twins or multiples.
  • If you have any existing medical condition that may complicate your delivery.
  • If you’re above 35 years of age.
  • If you have a problem that has been detected in your previous scans.
  • If you have a history of miscarriages or stillbirth.

Ultrasound scans can help you understand how your baby is developing and help your doctor detect any complications. The benefits of the ultrasound scans outweight the possible risks in cases where your pregnancy requires monitoring. But if you have doubts about it, it is suggested that you address any concerns you may have about this with your doctor; your doctor will be able to guide you the best.

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