From the Guidelines
There are no confirmed harmful bioeffects on pregnant women or their fetuses from the use of real-time diagnostic ultrasound instruments when used appropriately for medical purposes. Diagnostic ultrasound has been used for decades in obstetrics with an excellent safety record, as recently reaffirmed by the American College of Radiology in their 2024 update on multiple gestations 1. The acoustic energy used in standard diagnostic ultrasound is too low to cause tissue heating or cavitation at levels that would be harmful to the developing fetus or the mother.
Key Points to Consider
- Medical professionals follow the ALARA principle (As Low As Reasonably Achievable), meaning they use the lowest output settings necessary to obtain diagnostic information and limit scan duration to minimize any theoretical risk.
- While some studies have investigated potential associations between ultrasound exposure and subtle developmental effects, no conclusive evidence of harm has been established in clinical settings using standard diagnostic parameters, as noted in guidelines for assessing fetal well-being 1 and first-trimester vaginal bleeding 1.
- The benefits of diagnostic ultrasound during pregnancy—including accurate dating, anomaly detection, growth assessment, and placental evaluation—far outweigh any theoretical risks when the examination is medically indicated and performed by qualified healthcare providers.
Clinical Application
The use of ultrasound in pregnancy is critical for establishing the chorionicity and amnionicity of multiple gestations, guiding future clinical and imaging follow-up examinations, and assessing fetal well-being 1. It is essential for healthcare providers to be aware of the appropriate use of ultrasound and to follow established guidelines to ensure the safe and effective use of this technology. By doing so, they can maximize the benefits of diagnostic ultrasound while minimizing any potential risks.
From the Research
Confirmed Biological Effects on Pregnant Women
The use of real-time diagnostic instruments, such as ultrasound (ultrasonography), has been extensively studied in pregnant women. The confirmed biological effects of these instruments are as follows:
- Ultrasonography is considered harmless to the fetus and is the primary imaging modality used during pregnancy 2
- Other imaging modalities, such as x-ray, computed tomography (CT), and magnetic resonance imaging (MRI), should be reserved for cases where ultrasonography is inconclusive and patient care depends on further imaging 2
- MRI is the method of choice for pelvic disease, particularly concerning the ovaries and uterus, as well as fetal imaging 2
- The use of contrast media should only be given intravenously when a compelling clinical indication exists and the potential benefit to the patient outweighs the potential risk to the fetus 2
- Fetal radiation doses up to 1 mGy are considered acceptable, but larger doses may increase the risk of carcinogenesis 3
- No damage to a developing human fetus caused by MR imaging exposure has been documented, but caution is advised and risks and benefits must always be considered before evaluating a pregnant patient with MR imaging 3
Safety Considerations
The safety of diagnostic imaging during pregnancy is a major concern, and the following considerations must be taken into account:
- The use of iodinated contrast agents is generally safe during pregnancy, but should be used with caution due to the risk of fetal hypothyroidism 3
- The use of gadolinium-based contrast agents during pregnancy remains controversial due to lack of human clinical data and potential toxicity 4, 3
- Exposure to gadolinium-based contrast agents and sedation for MRI during pregnancy should be avoided whenever feasible 4
- Maternal and fetal radiation exposure and dose are affected by gestational age, anatomic site, modality, and technique 5